2005-04-16 15:20:36 -07:00
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2006-07-14 00:24:37 -07:00
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2005-04-16 15:20:36 -07:00
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2006-09-25 23:30:58 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] sparsemem memory model
Sparsemem abstracts the use of discontiguous mem_maps[]. This kind of
mem_map[] is needed by discontiguous memory machines (like in the old
CONFIG_DISCONTIGMEM case) as well as memory hotplug systems. Sparsemem
replaces DISCONTIGMEM when enabled, and it is hoped that it can eventually
become a complete replacement.
A significant advantage over DISCONTIGMEM is that it's completely separated
from CONFIG_NUMA. When producing this patch, it became apparent in that NUMA
and DISCONTIG are often confused.
Another advantage is that sparse doesn't require each NUMA node's ranges to be
contiguous. It can handle overlapping ranges between nodes with no problems,
where DISCONTIGMEM currently throws away that memory.
Sparsemem uses an array to provide different pfn_to_page() translations for
each SECTION_SIZE area of physical memory. This is what allows the mem_map[]
to be chopped up.
In order to do quick pfn_to_page() operations, the section number of the page
is encoded in page->flags. Part of the sparsemem infrastructure enables
sharing of these bits more dynamically (at compile-time) between the
page_zone() and sparsemem operations. However, on 32-bit architectures, the
number of bits is quite limited, and may require growing the size of the
page->flags type in certain conditions. Several things might force this to
occur: a decrease in the SECTION_SIZE (if you want to hotplug smaller areas of
memory), an increase in the physical address space, or an increase in the
number of used page->flags.
One thing to note is that, once sparsemem is present, the NUMA node
information no longer needs to be stored in the page->flags. It might provide
speed increases on certain platforms and will be stored there if there is
room. But, if out of room, an alternate (theoretically slower) mechanism is
used.
This patch introduces CONFIG_FLATMEM. It is used in almost all cases where
there used to be an #ifndef DISCONTIG, because SPARSEMEM and DISCONTIGMEM
often have to compile out the same areas of code.
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Martin Bligh <mbligh@aracnet.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: Bob Picco <bob.picco@hp.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 00:07:54 -07:00
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2005-04-16 15:20:36 -07:00
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2006-02-16 23:41:58 +01:00
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2006-03-31 02:30:33 -08:00
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2006-02-16 23:41:58 +01:00
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2005-04-16 15:20:36 -07:00
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[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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[PATCH] mm: split page table lock
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with
a many-threaded application which concurrently initializes different parts of
a large anonymous area.
This patch corrects that, by using a separate spinlock per page table page, to
guard the page table entries in that page, instead of using the mm's single
page_table_lock. (But even then, page_table_lock is still used to guard page
table allocation, and anon_vma allocation.)
In this implementation, the spinlock is tucked inside the struct page of the
page table page: with a BUILD_BUG_ON in case it overflows - which it would in
the case of 32-bit PA-RISC with spinlock debugging enabled.
Splitting the lock is not quite for free: another cacheline access. Ideally,
I suppose we would use split ptlock only for multi-threaded processes on
multi-cpu machines; but deciding that dynamically would have its own costs.
So for now enable it by config, at some number of cpus - since the Kconfig
language doesn't support inequalities, let preprocessor compare that with
NR_CPUS. But I don't think it's worth being user-configurable: for good
testing of both split and unsplit configs, split now at 4 cpus, and perhaps
change that to 8 later.
There is a benefit even for singly threaded processes: kswapd can be attacking
one part of the mm while another part is busy faulting.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:40 -07:00
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[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2006-06-30 01:55:38 -07:00
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[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
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|
[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
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|
[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
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|
[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
|
|
|
|
[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
|
|
[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
|
|
|
|
|
|
|
[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
|
[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
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|
|
|
|
|
|
|
[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
|
|
[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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|
|
2005-04-16 15:20:36 -07:00
|
|
|
|
[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
|
|
|
|
|
|
|
[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
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2005-04-19 13:29:16 -07:00
|
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|
|
[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
|
|
|
|
|
|
|
[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2005-04-19 13:29:16 -07:00
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2005-04-16 15:20:36 -07:00
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2005-04-19 13:29:16 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2005-10-29 18:16:02 -07:00
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2005-04-19 13:29:16 -07:00
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[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2005-04-19 13:29:16 -07:00
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[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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[PATCH] mm: unlink vma before pagetables
In most places the descent from pgd to pud to pmd to pte holds mmap_sem
(exclusively or not), which ensures that free_pgtables cannot be freeing page
tables from any level at the same time. But truncation and reverse mapping
descend without mmap_sem.
No problem: just make sure that a vma is unlinked from its prio_tree (or
nonlinear list) and from its anon_vma list, after zapping the vma, but before
freeing its page tables. Then neither vmtruncate nor rmap can reach that vma
whose page tables are now volatile (nor do they need to reach it, since all
its page entries have been zapped by this stage).
The i_mmap_lock and anon_vma->lock already serialize this correctly; but the
locking hierarchy is such that we cannot take them while holding
page_table_lock. Well, we're trying to push that down anyway. So in this
patch, move anon_vma_unlink and unlink_file_vma into free_pgtables, at the
same time as moving page_table_lock around calls to unmap_vmas.
tlb_gather_mmu and tlb_finish_mmu then fall outside the page_table_lock, but
we made them preempt_disable and preempt_enable earlier; and a long source
audit of all the architectures has shown no problem with removing
page_table_lock from them. free_pgtables doesn't need page_table_lock for
itself, nor for what it calls; tlb->mm->nr_ptes is usually protected by
page_table_lock, but partly by non-exclusive mmap_sem - here it's decremented
with exclusive mmap_sem, or mm_users 0. update_hiwater_rss and
vm_unacct_memory don't need page_table_lock either.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:29 -07:00
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[PATCH] hugepage: Fix hugepage logic in free_pgtables()
free_pgtables() has special logic to call hugetlb_free_pgd_range() instead
of the normal free_pgd_range() on hugepage VMAs. However, the test it uses
to do so is incorrect: it calls is_hugepage_only_range on a hugepage sized
range at the start of the vma. is_hugepage_only_range() will return true
if the given range has any intersection with a hugepage address region, and
in this case the given region need not be hugepage aligned. So, for
example, this test can return true if called on, say, a 4k VMA immediately
preceding a (nicely aligned) hugepage VMA.
At present we get away with this because the powerpc version of
hugetlb_free_pgd_range() is just a call to free_pgd_range(). On ia64 (the
only other arch with a non-trivial is_hugepage_only_range()) we get away
with it for a different reason; the hugepage area is not contiguous with
the rest of the user address space, and VMAs are not permitted in between,
so the test can't return a false positive there.
Nonetheless this should be fixed. We do that in the patch below by
replacing the is_hugepage_only_range() test with an explicit test of the
VMA using is_vm_hugetlb_page().
This in turn changes behaviour for platforms where is_hugepage_only_range()
returns false always (everything except powerpc and ia64). We address this
by ensuring that hugetlb_free_pgd_range() is defined to be identical to
free_pgd_range() (instead of a no-op) on everything except ia64. Even so,
it will prevent some otherwise possible coalescing of calls down to
free_pgd_range(). Since this only happens for hugepage VMAs, removing this
small optimization seems unlikely to cause any trouble.
This patch causes no regressions on the libhugetlbfs testsuite - ppc64
POWER5 (8-way), ppc64 G5 (2-way) and i386 Pentium M (UP).
Signed-off-by: David Gibson <dwg@au1.ibm.com>
Cc: William Lee Irwin III <wli@holomorphy.com>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-22 00:08:57 -08:00
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2005-04-19 13:29:16 -07:00
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[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2005-04-19 13:29:16 -07:00
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2006-03-22 00:08:58 -08:00
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2005-04-19 13:29:16 -07:00
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[PATCH] mm: unlink vma before pagetables
In most places the descent from pgd to pud to pmd to pte holds mmap_sem
(exclusively or not), which ensures that free_pgtables cannot be freeing page
tables from any level at the same time. But truncation and reverse mapping
descend without mmap_sem.
No problem: just make sure that a vma is unlinked from its prio_tree (or
nonlinear list) and from its anon_vma list, after zapping the vma, but before
freeing its page tables. Then neither vmtruncate nor rmap can reach that vma
whose page tables are now volatile (nor do they need to reach it, since all
its page entries have been zapped by this stage).
The i_mmap_lock and anon_vma->lock already serialize this correctly; but the
locking hierarchy is such that we cannot take them while holding
page_table_lock. Well, we're trying to push that down anyway. So in this
patch, move anon_vma_unlink and unlink_file_vma into free_pgtables, at the
same time as moving page_table_lock around calls to unmap_vmas.
tlb_gather_mmu and tlb_finish_mmu then fall outside the page_table_lock, but
we made them preempt_disable and preempt_enable earlier; and a long source
audit of all the architectures has shown no problem with removing
page_table_lock from them. free_pgtables doesn't need page_table_lock for
itself, nor for what it calls; tlb->mm->nr_ptes is usually protected by
page_table_lock, but partly by non-exclusive mmap_sem - here it's decremented
with exclusive mmap_sem, or mm_users 0. update_hiwater_rss and
vm_unacct_memory don't need page_table_lock either.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:29 -07:00
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2005-04-19 13:29:16 -07:00
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[PATCH] freepgt: free_pgtables use vma list
Recent woes with some arches needing their own pgd_addr_end macro; and 4-level
clear_page_range regression since 2.6.10's clear_page_tables; and its
long-standing well-known inefficiency in searching throughout the higher-level
page tables for those few entries to clear and free: all can be blamed on
ignoring the list of vmas when we free page tables.
Replace exit_mmap's clear_page_range of the total user address space by
free_pgtables operating on the mm's vma list; unmap_region use it in the same
way, giving floor and ceiling beyond which it may not free tables. This
brings lmbench fork/exec/sh numbers back to 2.6.10 (unless preempt is enabled,
in which case latency fixes spoil unmap_vmas throughput).
Beware: the do_mmap_pgoff driver failure case must now use unmap_region
instead of zap_page_range, since a page table might have been allocated, and
can only be freed while it is touched by some vma.
Move free_pgtables from mmap.c to memory.c, where its lower levels are adapted
from the clear_page_range levels. (Most of free_pgtables' old code was
actually for a non-existent case, prev not properly set up, dating from before
hch gave us split_vma.) Pass mmu_gather** in the public interfaces, since we
might want to add latency lockdrops later; but no attempt to do so yet, going
by vma should itself reduce latency.
But what if is_hugepage_only_range? Those ia64 and ppc64 cases need careful
examination: put that off until a later patch of the series.
What of x86_64's 32bit vdso page __map_syscall32 maps outside any vma?
And the range to sparc64's flush_tlb_pgtables? It's less clear to me now that
we need to do more than is done here - every PMD_SIZE ever occupied will be
flushed, do we really have to flush every PGDIR_SIZE ever partially occupied?
A shame to complicate it unnecessarily.
Special thanks to David Miller for time spent repairing my ceilings.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:22 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:23 -07:00
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2005-10-29 18:16:22 -07:00
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[PATCH] mm: split page table lock
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with
a many-threaded application which concurrently initializes different parts of
a large anonymous area.
This patch corrects that, by using a separate spinlock per page table page, to
guard the page table entries in that page, instead of using the mm's single
page_table_lock. (But even then, page_table_lock is still used to guard page
table allocation, and anon_vma allocation.)
In this implementation, the spinlock is tucked inside the struct page of the
page table page: with a BUILD_BUG_ON in case it overflows - which it would in
the case of 32-bit PA-RISC with spinlock debugging enabled.
Splitting the lock is not quite for free: another cacheline access. Ideally,
I suppose we would use split ptlock only for multi-threaded processes on
multi-cpu machines; but deciding that dynamically would have its own costs.
So for now enable it by config, at some number of cpus - since the Kconfig
language doesn't support inequalities, let preprocessor compare that with
NR_CPUS. But I don't think it's worth being user-configurable: for good
testing of both split and unsplit configs, split now at 4 cpus, and perhaps
change that to 8 later.
There is a benefit even for singly threaded processes: kswapd can be attacking
one part of the mm while another part is busy faulting.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:40 -07:00
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2005-10-29 18:16:23 -07:00
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[PATCH] mm: split page table lock
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with
a many-threaded application which concurrently initializes different parts of
a large anonymous area.
This patch corrects that, by using a separate spinlock per page table page, to
guard the page table entries in that page, instead of using the mm's single
page_table_lock. (But even then, page_table_lock is still used to guard page
table allocation, and anon_vma allocation.)
In this implementation, the spinlock is tucked inside the struct page of the
page table page: with a BUILD_BUG_ON in case it overflows - which it would in
the case of 32-bit PA-RISC with spinlock debugging enabled.
Splitting the lock is not quite for free: another cacheline access. Ideally,
I suppose we would use split ptlock only for multi-threaded processes on
multi-cpu machines; but deciding that dynamically would have its own costs.
So for now enable it by config, at some number of cpus - since the Kconfig
language doesn't support inequalities, let preprocessor compare that with
NR_CPUS. But I don't think it's worth being user-configurable: for good
testing of both split and unsplit configs, split now at 4 cpus, and perhaps
change that to 8 later.
There is a benefit even for singly threaded processes: kswapd can be attacking
one part of the mm while another part is busy faulting.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:40 -07:00
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2005-10-29 18:16:22 -07:00
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[PATCH] mm: split page table lock
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with
a many-threaded application which concurrently initializes different parts of
a large anonymous area.
This patch corrects that, by using a separate spinlock per page table page, to
guard the page table entries in that page, instead of using the mm's single
page_table_lock. (But even then, page_table_lock is still used to guard page
table allocation, and anon_vma allocation.)
In this implementation, the spinlock is tucked inside the struct page of the
page table page: with a BUILD_BUG_ON in case it overflows - which it would in
the case of 32-bit PA-RISC with spinlock debugging enabled.
Splitting the lock is not quite for free: another cacheline access. Ideally,
I suppose we would use split ptlock only for multi-threaded processes on
multi-cpu machines; but deciding that dynamically would have its own costs.
So for now enable it by config, at some number of cpus - since the Kconfig
language doesn't support inequalities, let preprocessor compare that with
NR_CPUS. But I don't think it's worth being user-configurable: for good
testing of both split and unsplit configs, split now at 4 cpus, and perhaps
change that to 8 later.
There is a benefit even for singly threaded processes: kswapd can be attacking
one part of the mm while another part is busy faulting.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:40 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-30 01:55:38 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:23 -07:00
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2005-10-29 18:16:22 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:22 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:22 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:05 -07:00
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2005-10-29 18:16:12 -07:00
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2005-11-28 14:34:23 -08:00
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2005-10-29 18:16:12 -07:00
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2005-12-11 20:38:17 -08:00
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[PATCH] unpaged: anon in VM_UNPAGED
copy_one_pte needs to copy the anonymous COWed pages in a VM_UNPAGED area,
zap_pte_range needs to free them, do_wp_page needs to COW them: just like
ordinary pages, not like the unpaged.
But recognizing them is a little subtle: because PageReserved is no longer a
condition for remap_pfn_range, we can now mmap all of /dev/mem (whether the
distro permits, and whether it's advisable on this or that architecture, is
another matter). So if we can see a PageAnon, it may not be ours to mess with
(or may be ours from elsewhere in the address space). I suspect there's an
entertaining insoluble self-referential problem here, but the page_is_anon
function does a good practical job, and MAP_PRIVATE PROT_WRITE VM_UNPAGED will
always be an odd choice.
In updating the comment on page_address_in_vma, noticed a potential NULL
dereference, in a path we don't actually take, but fixed it.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-21 21:32:18 -08:00
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2005-11-28 14:34:23 -08:00
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[PATCH] unpaged: anon in VM_UNPAGED
copy_one_pte needs to copy the anonymous COWed pages in a VM_UNPAGED area,
zap_pte_range needs to free them, do_wp_page needs to COW them: just like
ordinary pages, not like the unpaged.
But recognizing them is a little subtle: because PageReserved is no longer a
condition for remap_pfn_range, we can now mmap all of /dev/mem (whether the
distro permits, and whether it's advisable on this or that architecture, is
another matter). So if we can see a PageAnon, it may not be ours to mess with
(or may be ours from elsewhere in the address space). I suspect there's an
entertaining insoluble self-referential problem here, but the page_is_anon
function does a good practical job, and MAP_PRIVATE PROT_WRITE VM_UNPAGED will
always be an odd choice.
In updating the comment on page_address_in_vma, noticed a potential NULL
dereference, in a path we don't actually take, but fixed it.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-21 21:32:18 -08:00
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2005-11-28 14:34:23 -08:00
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|
[PATCH] unpaged: anon in VM_UNPAGED
copy_one_pte needs to copy the anonymous COWed pages in a VM_UNPAGED area,
zap_pte_range needs to free them, do_wp_page needs to COW them: just like
ordinary pages, not like the unpaged.
But recognizing them is a little subtle: because PageReserved is no longer a
condition for remap_pfn_range, we can now mmap all of /dev/mem (whether the
distro permits, and whether it's advisable on this or that architecture, is
another matter). So if we can see a PageAnon, it may not be ours to mess with
(or may be ours from elsewhere in the address space). I suspect there's an
entertaining insoluble self-referential problem here, but the page_is_anon
function does a good practical job, and MAP_PRIVATE PROT_WRITE VM_UNPAGED will
always be an odd choice.
In updating the comment on page_address_in_vma, noticed a potential NULL
dereference, in a path we don't actually take, but fixed it.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-21 21:32:18 -08:00
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2005-11-28 14:34:23 -08:00
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2006-03-22 00:08:42 -08:00
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2005-11-28 14:34:23 -08:00
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2005-12-11 20:38:17 -08:00
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2005-12-11 19:46:02 -08:00
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2005-11-28 14:34:23 -08:00
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2006-03-25 16:20:22 +01:00
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2005-11-28 14:34:23 -08:00
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[PATCH] unpaged: anon in VM_UNPAGED
copy_one_pte needs to copy the anonymous COWed pages in a VM_UNPAGED area,
zap_pte_range needs to free them, do_wp_page needs to COW them: just like
ordinary pages, not like the unpaged.
But recognizing them is a little subtle: because PageReserved is no longer a
condition for remap_pfn_range, we can now mmap all of /dev/mem (whether the
distro permits, and whether it's advisable on this or that architecture, is
another matter). So if we can see a PageAnon, it may not be ours to mess with
(or may be ours from elsewhere in the address space). I suspect there's an
entertaining insoluble self-referential problem here, but the page_is_anon
function does a good practical job, and MAP_PRIVATE PROT_WRITE VM_UNPAGED will
always be an odd choice.
In updating the comment on page_address_in_vma, noticed a potential NULL
dereference, in a path we don't actually take, but fixed it.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-21 21:32:18 -08:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:13 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:12 -07:00
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2005-10-29 18:16:13 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:12 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] Swapless page migration: add R/W migration entries
Implement read/write migration ptes
We take the upper two swapfiles for the two types of migration ptes and define
a series of macros in swapops.h.
The VM is modified to handle the migration entries. migration entries can
only be encountered when the page they are pointing to is locked. This limits
the number of places one has to fix. We also check in copy_pte_range and in
mprotect_pte_range() for migration ptes.
We check for migration ptes in do_swap_cache and call a function that will
then wait on the page lock. This allows us to effectively stop all accesses
to apge.
Migration entries are created by try_to_unmap if called for migration and
removed by local functions in migrate.c
From: Hugh Dickins <hugh@veritas.com>
Several times while testing swapless page migration (I've no NUMA, just
hacking it up to migrate recklessly while running load), I've hit the
BUG_ON(!PageLocked(p)) in migration_entry_to_page.
This comes from an orphaned migration entry, unrelated to the current
correctly locked migration, but hit by remove_anon_migration_ptes as it
checks an address in each vma of the anon_vma list.
Such an orphan may be left behind if an earlier migration raced with fork:
copy_one_pte can duplicate a migration entry from parent to child, after
remove_anon_migration_ptes has checked the child vma, but before it has
removed it from the parent vma. (If the process were later to fault on this
orphaned entry, it would hit the same BUG from migration_entry_wait.)
This could be fixed by locking anon_vma in copy_one_pte, but we'd rather
not. There's no such problem with file pages, because vma_prio_tree_add
adds child vma after parent vma, and the page table locking at each end is
enough to serialize. Follow that example with anon_vma: add new vmas to the
tail instead of the head.
(There's no corresponding problem when inserting migration entries,
because a missed pte will leave the page count and mapcount high, which is
allowed for. And there's no corresponding problem when migrating via swap,
because a leftover swap entry will be correctly faulted. But the swapless
method has no refcounting of its entries.)
From: Ingo Molnar <mingo@elte.hu>
pte_unmap_unlock() takes the pte pointer as an argument.
From: Hugh Dickins <hugh@veritas.com>
Several times while testing swapless page migration, gcc has tried to exec
a pointer instead of a string: smells like COW mappings are not being
properly write-protected on fork.
The protection in copy_one_pte looks very convincing, until at last you
realize that the second arg to make_migration_entry is a boolean "write",
and SWP_MIGRATION_READ is 30.
Anyway, it's better done like in change_pte_range, using
is_write_migration_entry and make_migration_entry_read.
From: Hugh Dickins <hugh@veritas.com>
Remove unnecessary obfuscation from sys_swapon's range check on swap type,
which blew up causing memory corruption once swapless migration made
MAX_SWAPFILES no longer 2 ^ MAX_SWAPFILES_SHIFT.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
From: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 02:03:35 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:41 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] Swapless page migration: add R/W migration entries
Implement read/write migration ptes
We take the upper two swapfiles for the two types of migration ptes and define
a series of macros in swapops.h.
The VM is modified to handle the migration entries. migration entries can
only be encountered when the page they are pointing to is locked. This limits
the number of places one has to fix. We also check in copy_pte_range and in
mprotect_pte_range() for migration ptes.
We check for migration ptes in do_swap_cache and call a function that will
then wait on the page lock. This allows us to effectively stop all accesses
to apge.
Migration entries are created by try_to_unmap if called for migration and
removed by local functions in migrate.c
From: Hugh Dickins <hugh@veritas.com>
Several times while testing swapless page migration (I've no NUMA, just
hacking it up to migrate recklessly while running load), I've hit the
BUG_ON(!PageLocked(p)) in migration_entry_to_page.
This comes from an orphaned migration entry, unrelated to the current
correctly locked migration, but hit by remove_anon_migration_ptes as it
checks an address in each vma of the anon_vma list.
Such an orphan may be left behind if an earlier migration raced with fork:
copy_one_pte can duplicate a migration entry from parent to child, after
remove_anon_migration_ptes has checked the child vma, but before it has
removed it from the parent vma. (If the process were later to fault on this
orphaned entry, it would hit the same BUG from migration_entry_wait.)
This could be fixed by locking anon_vma in copy_one_pte, but we'd rather
not. There's no such problem with file pages, because vma_prio_tree_add
adds child vma after parent vma, and the page table locking at each end is
enough to serialize. Follow that example with anon_vma: add new vmas to the
tail instead of the head.
(There's no corresponding problem when inserting migration entries,
because a missed pte will leave the page count and mapcount high, which is
allowed for. And there's no corresponding problem when migrating via swap,
because a leftover swap entry will be correctly faulted. But the swapless
method has no refcounting of its entries.)
From: Ingo Molnar <mingo@elte.hu>
pte_unmap_unlock() takes the pte pointer as an argument.
From: Hugh Dickins <hugh@veritas.com>
Several times while testing swapless page migration, gcc has tried to exec
a pointer instead of a string: smells like COW mappings are not being
properly write-protected on fork.
The protection in copy_one_pte looks very convincing, until at last you
realize that the second arg to make_migration_entry is a boolean "write",
and SWP_MIGRATION_READ is 30.
Anyway, it's better done like in change_pte_range, using
is_write_migration_entry and make_migration_entry_read.
From: Hugh Dickins <hugh@veritas.com>
Remove unnecessary obfuscation from sys_swapon's range check on swap type,
which blew up causing memory corruption once swapless migration made
MAX_SWAPFILES no longer 2 ^ MAX_SWAPFILES_SHIFT.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
From: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 02:03:35 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:05 -07:00
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2005-04-16 15:20:36 -07:00
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2005-12-11 20:38:17 -08:00
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2005-04-16 15:20:36 -07:00
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2006-09-30 23:29:30 -07:00
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2005-04-16 15:20:36 -07:00
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2005-11-28 14:34:23 -08:00
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2005-10-29 18:16:05 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:23 -07:00
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2005-10-29 18:15:53 -07:00
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2005-10-29 18:16:13 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:05 -07:00
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2005-10-29 18:16:23 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: split page table lock
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with
a many-threaded application which concurrently initializes different parts of
a large anonymous area.
This patch corrects that, by using a separate spinlock per page table page, to
guard the page table entries in that page, instead of using the mm's single
page_table_lock. (But even then, page_table_lock is still used to guard page
table allocation, and anon_vma allocation.)
In this implementation, the spinlock is tucked inside the struct page of the
page table page: with a BUILD_BUG_ON in case it overflows - which it would in
the case of 32-bit PA-RISC with spinlock debugging enabled.
Splitting the lock is not quite for free: another cacheline access. Ideally,
I suppose we would use split ptlock only for multi-threaded processes on
multi-cpu machines; but deciding that dynamically would have its own costs.
So for now enable it by config, at some number of cpus - since the Kconfig
language doesn't support inequalities, let preprocessor compare that with
NR_CPUS. But I don't think it's worth being user-configurable: for good
testing of both split and unsplit configs, split now at 4 cpus, and perhaps
change that to 8 later.
There is a benefit even for singly threaded processes: kswapd can be attacking
one part of the mm while another part is busy faulting.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:40 -07:00
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2006-07-03 00:25:08 -07:00
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2006-09-30 23:29:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:15:53 -07:00
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2005-10-29 18:16:23 -07:00
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2005-10-29 18:15:53 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:13 -07:00
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2005-04-16 15:20:36 -07:00
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2006-09-30 23:29:33 -07:00
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2005-10-29 18:16:23 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:05 -07:00
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2005-10-29 18:16:23 -07:00
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2005-04-16 15:20:36 -07:00
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2005-08-28 16:49:11 +10:00
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2005-12-16 10:21:23 -08:00
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2005-08-28 16:49:11 +10:00
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2005-04-16 15:20:36 -07:00
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2005-11-13 16:06:42 -08:00
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2005-10-29 18:16:12 -07:00
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2005-04-16 15:20:36 -07:00
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2005-11-13 16:06:42 -08:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:12 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:30 -07:00
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2005-10-29 18:16:05 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:30 -07:00
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2006-09-30 23:29:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-11-13 16:06:42 -08:00
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2005-04-16 15:20:36 -07:00
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2005-11-13 16:06:42 -08:00
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2006-03-16 23:04:09 -08:00
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2005-04-16 15:20:36 -07:00
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[PATCH] unpaged: anon in VM_UNPAGED
copy_one_pte needs to copy the anonymous COWed pages in a VM_UNPAGED area,
zap_pte_range needs to free them, do_wp_page needs to COW them: just like
ordinary pages, not like the unpaged.
But recognizing them is a little subtle: because PageReserved is no longer a
condition for remap_pfn_range, we can now mmap all of /dev/mem (whether the
distro permits, and whether it's advisable on this or that architecture, is
another matter). So if we can see a PageAnon, it may not be ours to mess with
(or may be ours from elsewhere in the address space). I suspect there's an
entertaining insoluble self-referential problem here, but the page_is_anon
function does a good practical job, and MAP_PRIVATE PROT_WRITE VM_UNPAGED will
always be an odd choice.
In updating the comment on page_address_in_vma, noticed a potential NULL
dereference, in a path we don't actually take, but fixed it.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-21 21:32:18 -08:00
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2005-11-13 16:06:42 -08:00
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2005-11-28 14:34:23 -08:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:12 -07:00
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[PATCH] x86: ptep_clear optimization
Add a new accessor for PTEs, which passes the full hint from the mmu_gather
struct; this allows architectures with hardware pagetables to optimize away
atomic PTE operations when destroying an address space. Removing the
locked operation should allow better pipelining of memory access in this
loop. I measured an average savings of 30-35 cycles per zap_pte_range on
the first 500 destructions on Pentium-M, but I believe the optimization
would win more on older processors which still assert the bus lock on xchg
for an exclusive cacheline.
Update: I made some new measurements, and this saves exactly 26 cycles over
ptep_get_and_clear on Pentium M. On P4, with a PAE kernel, this saves 180
cycles per ptep_get_and_clear, for a whopping 92160 cycles savings for a
full address space destruction.
pte_clear_full is not yet used, but is provided for future optimizations
(in particular, when running inside of a hypervisor that queues page table
updates, the full hint allows us to avoid queueing unnecessary page table
update for an address space in the process of being destroyed.
This is not a huge win, but it does help a bit, and sets the stage for
further hypervisor optimization of the mm layer on all architectures.
Signed-off-by: Zachary Amsden <zach@vmware.com>
Cc: Christoph Lameter <christoph@lameter.com>
Cc: <linux-mm@kvack.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-03 15:55:04 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:12 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:14 -07:00
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2005-10-29 18:15:54 -07:00
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2005-10-29 18:16:14 -07:00
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2005-10-29 18:15:54 -07:00
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2005-04-16 15:20:36 -07:00
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2006-09-30 23:29:31 -07:00
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2005-11-13 16:06:42 -08:00
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2005-10-29 18:16:05 -07:00
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2005-10-29 18:16:14 -07:00
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2006-09-30 23:29:33 -07:00
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2005-10-29 18:16:30 -07:00
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2005-11-13 16:06:42 -08:00
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2005-04-16 15:20:36 -07:00
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2005-11-13 16:06:42 -08:00
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2005-10-29 18:16:12 -07:00
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2005-04-16 15:20:36 -07:00
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2005-11-13 16:06:42 -08:00
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2005-04-16 15:20:36 -07:00
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2005-11-13 16:06:42 -08:00
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2005-04-16 15:20:36 -07:00
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2005-11-13 16:06:42 -08:00
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2005-04-16 15:20:36 -07:00
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2005-11-13 16:06:42 -08:00
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2005-10-29 18:16:12 -07:00
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2005-04-16 15:20:36 -07:00
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2005-04-16 15:20:36 -07:00
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2005-11-13 16:06:42 -08:00
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2005-04-16 15:20:36 -07:00
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2005-11-13 16:06:42 -08:00
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2005-04-16 15:20:36 -07:00
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2005-11-13 16:06:42 -08:00
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2005-04-16 15:20:36 -07:00
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2005-04-16 15:20:36 -07:00
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2005-11-13 16:06:42 -08:00
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2005-04-16 15:20:36 -07:00
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2005-11-13 16:06:42 -08:00
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2005-04-16 15:20:36 -07:00
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2005-11-13 16:06:42 -08:00
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2005-04-19 13:29:15 -07:00
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2005-11-13 16:06:42 -08:00
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2005-11-13 16:06:42 -08:00
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2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
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2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: update_hiwaters just in time
update_mem_hiwater has attracted various criticisms, in particular from those
concerned with mm scalability. Originally it was called whenever rss or
total_vm got raised. Then many of those callsites were replaced by a timer
tick call from account_system_time. Now Frank van Maarseveen reports that to
be found inadequate. How about this? Works for Frank.
Replace update_mem_hiwater, a poor combination of two unrelated ops, by macros
update_hiwater_rss and update_hiwater_vm. Don't attempt to keep
mm->hiwater_rss up to date at timer tick, nor every time we raise rss (usually
by 1): those are hot paths. Do the opposite, update only when about to lower
rss (usually by many), or just before final accounting in do_exit. Handle
mm->hiwater_vm in the same way, though it's much less of an issue. Demand
that whoever collects these hiwater statistics do the work of taking the
maximum with rss or total_vm.
And there has been no collector of these hiwater statistics in the tree. The
new convention needs an example, so match Frank's usage by adding a VmPeak
line above VmSize to /proc/<pid>/status, and also a VmHWM line above VmRSS
(High-Water-Mark or High-Water-Memory).
There was a particular anomaly during mremap move, that hiwater_vm might be
captured too high. A fleeting such anomaly remains, but it's quickly
corrected now, whereas before it would stick.
What locking? None: if the app is racy then these statistics will be racy,
it's not worth any overhead to make them exact. But whenever it suits,
hiwater_vm is updated under exclusive mmap_sem, and hiwater_rss under
page_table_lock (for now) or with preemption disabled (later on): without
going to any trouble, minimize the time between reading current values and
updating, to minimize those occasions when a racing thread bumps a count up
and back down in between.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:18 -07:00
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2005-10-29 18:16:30 -07:00
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2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
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2005-11-28 14:34:23 -08:00
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2005-10-29 18:16:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-11-28 14:34:23 -08:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:33 -07:00
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2005-11-28 14:34:23 -08:00
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2005-10-29 18:16:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-08-01 21:11:42 -07:00
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2005-04-16 15:20:36 -07:00
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2005-08-01 21:11:42 -07:00
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2005-04-16 15:20:36 -07:00
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2005-11-29 18:43:17 +11:00
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2005-11-28 14:34:23 -08:00
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2005-04-16 15:20:36 -07:00
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2005-12-12 16:24:33 -08:00
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2005-10-29 18:16:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-06-21 17:15:10 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:33 -07:00
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2005-08-03 10:07:09 -07:00
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2005-10-29 18:16:33 -07:00
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2005-11-28 14:34:23 -08:00
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2005-10-29 18:16:33 -07:00
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2005-08-03 10:07:09 -07:00
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2005-10-29 18:16:33 -07:00
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2005-08-03 10:07:09 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] page fault retry with NOPAGE_REFAULT
Add a way for a no_page() handler to request a retry of the faulting
instruction. It goes back to userland on page faults and just tries again
in get_user_pages(). I added a cond_resched() in the loop in that later
case.
The problem I have with signal and spufs is an actual bug affecting apps and I
don't see other ways of fixing it.
In addition, we are having issues with infiniband and 64k pages (related to
the way the hypervisor deals with some HV cards) that will require us to muck
around with the MMU from within the IB driver's no_page() (it's a pSeries
specific driver) and return to the caller the same way using NOPAGE_REFAULT.
And to add to this, the graphics folks have been following a new approach of
memory management that involves transparently swapping objects between video
ram and main meory. To do that, they need installing PTEs from a no_page()
handler as well and that also requires returning with NOPAGE_REFAULT.
(For the later, they are currently using io_remap_pfn_range to install one PTE
from no_page() which is a bit racy, we need to add a check for the PTE having
already been installed afer taking the lock, but that's ok, they are only at
the proof-of-concept stage. I'll send a patch adding a "clean" function to do
that, we can use that from spufs too and get rid of the sparsemem hacks we do
to create struct page for SPEs. Basically, that provides a generic solution
for being able to have no_page() map hardware devices, which is something that
I think sound driver folks have been asking for some time too).
All of these things depend on having the NOPAGE_REFAULT exit path from
no_page() handlers.
Signed-off-by: Benjamin Herrenchmidt <benh@kernel.crashing.org>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-06 00:43:53 -07:00
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2005-04-16 15:20:36 -07:00
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2005-06-21 17:15:10 -07:00
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2006-03-26 01:36:57 -08:00
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2005-06-21 17:15:10 -07:00
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2005-04-16 15:20:36 -07:00
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2005-06-21 17:15:10 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:23 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:23 -07:00
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2005-04-16 15:20:36 -07:00
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2006-09-30 23:29:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:12 -07:00
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2005-04-16 15:20:36 -07:00
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2006-09-30 23:29:33 -07:00
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2005-10-29 18:16:23 -07:00
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2005-04-16 15:20:36 -07:00
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2005-11-29 19:27:22 -05:00
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2005-11-29 14:03:14 -08:00
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2005-11-29 19:27:22 -05:00
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2005-11-29 14:03:14 -08:00
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2005-11-29 13:01:56 -08:00
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2005-11-29 14:03:14 -08:00
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2005-11-29 13:01:56 -08:00
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2005-11-30 09:35:19 -08:00
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2005-11-29 13:01:56 -08:00
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2005-11-29 14:03:14 -08:00
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2005-11-29 13:01:56 -08:00
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2006-09-25 23:31:22 -07:00
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2005-11-30 09:35:19 -08:00
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2006-03-22 00:08:05 -08:00
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2005-11-30 09:35:19 -08:00
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2005-12-16 10:21:23 -08:00
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2005-11-30 09:35:19 -08:00
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2005-12-03 20:48:11 -08:00
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2005-11-30 09:35:19 -08:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:23 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:23 -07:00
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2005-04-16 15:20:36 -07:00
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2006-09-30 23:29:33 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:12 -07:00
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2005-04-16 15:20:36 -07:00
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2006-09-30 23:29:33 -07:00
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2005-10-29 18:16:23 -07:00
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2005-04-16 15:20:36 -07:00
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2006-09-25 23:31:22 -07:00
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2005-04-16 15:20:36 -07:00
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2005-06-25 14:54:33 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] unpaged: VM_UNPAGED
Although we tend to associate VM_RESERVED with remap_pfn_range, quite a few
drivers set VM_RESERVED on areas which are then populated by nopage. The
PageReserved removal in 2.6.15-rc1 changed VM_RESERVED not to free pages in
zap_pte_range, without changing those drivers not to set it: so their pages
just leak away.
Let's not change miscellaneous drivers now: introduce VM_UNPAGED at the core,
to flag the special areas where the ptes may have no struct page, or if they
have then it's not to be touched. Replace most instances of VM_RESERVED in
core mm by VM_UNPAGED. Force it on in remap_pfn_range, and the sparc and
sparc64 io_remap_pfn_range.
Revert addition of VM_RESERVED to powerpc vdso, it's not needed there. Is it
needed anywhere? It still governs the mm->reserved_vm statistic, and special
vmas not to be merged, and areas not to be core dumped; but could probably be
eliminated later (the drivers are probably specifying it because in 2.4 it
kept swapout off the vma, but in 2.6 we work from the LRU, which these pages
don't get on).
Use the VM_SHM slot for VM_UNPAGED, and define VM_SHM to 0: it serves no
purpose whatsoever, and should be removed from drivers when we clean up.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: William Irwin <wli@holomorphy.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-21 21:32:15 -08:00
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2005-11-28 14:34:23 -08:00
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2005-12-11 19:46:02 -08:00
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2005-04-16 15:20:36 -07:00
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2005-12-11 20:38:17 -08:00
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2005-12-11 19:46:02 -08:00
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2005-12-11 19:57:52 -08:00
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2005-12-11 19:46:02 -08:00
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2005-11-28 14:34:23 -08:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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[PATCH] mm: split page table lock
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with
a many-threaded application which concurrently initializes different parts of
a large anonymous area.
This patch corrects that, by using a separate spinlock per page table page, to
guard the page table entries in that page, instead of using the mm's single
page_table_lock. (But even then, page_table_lock is still used to guard page
table allocation, and anon_vma allocation.)
In this implementation, the spinlock is tucked inside the struct page of the
page table page: with a BUILD_BUG_ON in case it overflows - which it would in
the case of 32-bit PA-RISC with spinlock debugging enabled.
Splitting the lock is not quite for free: another cacheline access. Ideally,
I suppose we would use split ptlock only for multi-threaded processes on
multi-cpu machines; but deciding that dynamically would have its own costs.
So for now enable it by config, at some number of cpus - since the Kconfig
language doesn't support inequalities, let preprocessor compare that with
NR_CPUS. But I don't think it's worth being user-configurable: for good
testing of both split and unsplit configs, split now at 4 cpus, and perhaps
change that to 8 later.
There is a benefit even for singly threaded processes: kswapd can be attacking
one part of the mm while another part is busy faulting.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:40 -07:00
|
|
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|
[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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|
[PATCH] mm: split page table lock
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with
a many-threaded application which concurrently initializes different parts of
a large anonymous area.
This patch corrects that, by using a separate spinlock per page table page, to
guard the page table entries in that page, instead of using the mm's single
page_table_lock. (But even then, page_table_lock is still used to guard page
table allocation, and anon_vma allocation.)
In this implementation, the spinlock is tucked inside the struct page of the
page table page: with a BUILD_BUG_ON in case it overflows - which it would in
the case of 32-bit PA-RISC with spinlock debugging enabled.
Splitting the lock is not quite for free: another cacheline access. Ideally,
I suppose we would use split ptlock only for multi-threaded processes on
multi-cpu machines; but deciding that dynamically would have its own costs.
So for now enable it by config, at some number of cpus - since the Kconfig
language doesn't support inequalities, let preprocessor compare that with
NR_CPUS. But I don't think it's worth being user-configurable: for good
testing of both split and unsplit configs, split now at 4 cpus, and perhaps
change that to 8 later.
There is a benefit even for singly threaded processes: kswapd can be attacking
one part of the mm while another part is busy faulting.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:40 -07:00
|
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|
[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
|
|
|
|
[PATCH] mm: split page table lock
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with
a many-threaded application which concurrently initializes different parts of
a large anonymous area.
This patch corrects that, by using a separate spinlock per page table page, to
guard the page table entries in that page, instead of using the mm's single
page_table_lock. (But even then, page_table_lock is still used to guard page
table allocation, and anon_vma allocation.)
In this implementation, the spinlock is tucked inside the struct page of the
page table page: with a BUILD_BUG_ON in case it overflows - which it would in
the case of 32-bit PA-RISC with spinlock debugging enabled.
Splitting the lock is not quite for free: another cacheline access. Ideally,
I suppose we would use split ptlock only for multi-threaded processes on
multi-cpu machines; but deciding that dynamically would have its own costs.
So for now enable it by config, at some number of cpus - since the Kconfig
language doesn't support inequalities, let preprocessor compare that with
NR_CPUS. But I don't think it's worth being user-configurable: for good
testing of both split and unsplit configs, split now at 4 cpus, and perhaps
change that to 8 later.
There is a benefit even for singly threaded processes: kswapd can be attacking
one part of the mm while another part is busy faulting.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:40 -07:00
|
|
|
|
[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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2005-11-28 14:34:23 -08:00
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2005-11-29 14:07:55 -08:00
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2005-11-28 14:34:23 -08:00
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[PATCH] mm: D-cache aliasing issue in cow_user_page
--=-=-=
from mm/memory.c:
1434 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va)
1435 {
1436 /*
1437 * If the source page was a PFN mapping, we don't have
1438 * a "struct page" for it. We do a best-effort copy by
1439 * just copying from the original user address. If that
1440 * fails, we just zero-fill it. Live with it.
1441 */
1442 if (unlikely(!src)) {
1443 void *kaddr = kmap_atomic(dst, KM_USER0);
1444 void __user *uaddr = (void __user *)(va & PAGE_MASK);
1445
1446 /*
1447 * This really shouldn't fail, because the page is there
1448 * in the page tables. But it might just be unreadable,
1449 * in which case we just give up and fill the result with
1450 * zeroes.
1451 */
1452 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
1453 memset(kaddr, 0, PAGE_SIZE);
1454 kunmap_atomic(kaddr, KM_USER0);
#### D-cache have to be flushed here.
#### It seems it is just forgotten.
1455 return;
1456
1457 }
1458 copy_user_highpage(dst, src, va);
#### Ok here. flush_dcache_page() called from this func if arch need it
1459 }
Following is the patch fix this issue:
Signed-off-by: Dmitriy Monakhov <dmonakhov@openvz.org>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-19 23:29:08 -07:00
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2005-11-28 14:34:23 -08:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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2005-11-29 16:54:51 +00:00
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2005-04-16 15:20:36 -07:00
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2006-09-25 23:30:57 -07:00
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2005-04-16 15:20:36 -07:00
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2005-11-28 14:34:23 -08:00
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2005-04-16 15:20:36 -07:00
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2006-09-25 23:30:57 -07:00
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2006-09-25 23:31:00 -07:00
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2006-09-25 23:30:57 -07:00
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2006-09-25 23:31:00 -07:00
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2006-09-25 23:30:57 -07:00
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2006-09-25 23:31:00 -07:00
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2006-06-23 02:03:43 -07:00
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2005-04-16 15:20:36 -07:00
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2006-09-25 23:30:57 -07:00
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2006-06-23 02:03:43 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:12 -07:00
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2005-11-21 21:32:17 -08:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-11-29 16:54:51 +00:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-11-29 16:54:51 +00:00
|
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2005-04-16 15:20:36 -07:00
|
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|
[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
|
|
|
|
[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-11-21 21:32:17 -08:00
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2005-10-29 18:16:05 -07:00
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2005-11-29 11:45:26 -08:00
|
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|
[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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[PATCH] ia64: race flushing icache in COW path
There is a race condition that showed up in a threaded JIT environment.
The situation is that a process with a JIT code page forks, so the page is
marked read-only, then some threads are created in the child. One of the
threads attempts to add a new code block to the JIT page, so a
copy-on-write fault is taken, and the kernel allocates a new page, copies
the data, installs the new pte, and then calls lazy_mmu_prot_update() to
flush caches to make sure that the icache and dcache are in sync.
Unfortunately, the other thread runs right after the new pte is installed,
but before the caches have been flushed. It tries to execute some old JIT
code that was already in this page, but it sees some garbage in the i-cache
from the previous users of the new physical page.
Fix: we must make the caches consistent before installing the pte. This is
an ia64 only fix because lazy_mmu_prot_update() is a no-op on all other
architectures.
Signed-off-by: Anil Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-14 00:23:57 -07:00
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|
[PATCH] mm: fix a race condition under SMC + COW
Failing context is a multi threaded process context and the failing
sequence is as follows.
One thread T0 doing self modifying code on page X on processor P0 and
another thread T1 doing COW (breaking the COW setup as part of just
happened fork() in another thread T2) on the same page X on processor P1.
T0 doing SMC can endup modifying the new page Y (allocated by the T1 doing
COW on P1) but because of different I/D TLB's, P0 ITLB will not see the new
mapping till the flush TLB IPI from P1 is received. During this interval,
if T0 executes the code created by SMC it can result in an app error (as
ITLB still points to old page X and endup executing the content in page X
rather than using the content in page Y).
Fix this issue by first clearing the PTE and flushing it, before updating
it with new entry.
Hugh sayeth:
I was a bit sceptical, in the habit of thinking that Self Modifying Code
must look such issues itself: but I guess there's nothing it can do to avoid
this one.
Fair enough, what you're changing it to is pretty much what powerpc and
s390 were already doing, and is a more robust way of proceeding, consistent
with how ptes are set everywhere else.
The ptep_clear_flush is a bit heavy-handed (it's anxious to return the pte
that was atomically cleared), but we'd have to wander through lots of arches
to get the right minimal behaviour. It'd also be nice to eliminate
ptep_establish completely, now only used to define other macros/inlines: it
always seemed obfuscation to me, what you've got there now is clearer.
Let's put those cleanups on a TODO list.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: "David S. Miller" <davem@davemloft.net>
Acked-by: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-29 01:58:42 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
|
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|
2005-04-16 15:20:36 -07:00
|
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2006-01-06 00:11:12 -08:00
|
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2005-04-16 15:20:36 -07:00
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[PATCH] fix get_user_pages bug
Checking pte_dirty instead of pte_write in __follow_page is problematic
for s390, and for copy_one_pte which leaves dirty when clearing write.
So revert __follow_page to check pte_write as before, and make
do_wp_page pass back a special extra VM_FAULT_WRITE bit to say it has
done its full job: once get_user_pages receives this value, it no longer
requires pte_write in __follow_page.
But most callers of handle_mm_fault, in the various architectures, have
switch statements which do not expect this new case. To avoid changing
them all in a hurry, make an inline wrapper function (using the old
name) that masks off the new bit, and use the extended interface with
double underscores.
Yes, we do have a call to do_wp_page from do_swap_page, but no need to
change that: in rare case it's needed, another do_wp_page will follow.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
[ Cleanups by Nick Piggin ]
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-08-03 20:24:01 +10:00
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2005-04-16 15:20:36 -07:00
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2005-11-21 21:32:17 -08:00
|
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2006-09-25 23:30:57 -07:00
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2006-09-25 23:30:58 -07:00
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2006-09-25 23:30:57 -07:00
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[PATCH] fix get_user_pages bug
Checking pte_dirty instead of pte_write in __follow_page is problematic
for s390, and for copy_one_pte which leaves dirty when clearing write.
So revert __follow_page to check pte_write as before, and make
do_wp_page pass back a special extra VM_FAULT_WRITE bit to say it has
done its full job: once get_user_pages receives this value, it no longer
requires pte_write in __follow_page.
But most callers of handle_mm_fault, in the various architectures, have
switch statements which do not expect this new case. To avoid changing
them all in a hurry, make an inline wrapper function (using the old
name) that masks off the new bit, and use the extended interface with
double underscores.
Yes, we do have a call to do_wp_page from do_swap_page, but no need to
change that: in rare case it's needed, another do_wp_page will follow.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
[ Cleanups by Nick Piggin ]
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-08-03 20:24:01 +10:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-11-21 21:32:17 -08:00
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2005-04-16 15:20:36 -07:00
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2006-06-23 02:03:43 -07:00
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2005-04-16 15:20:36 -07:00
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2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
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2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
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2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
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2005-04-19 13:29:15 -07:00
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2005-04-16 15:20:36 -07:00
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2005-06-23 22:05:21 -07:00
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2005-04-16 15:20:36 -07:00
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2006-09-25 23:31:22 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] madvise(MADV_REMOVE): remove pages from tmpfs shm backing store
Here is the patch to implement madvise(MADV_REMOVE) - which frees up a
given range of pages & its associated backing store. Current
implementation supports only shmfs/tmpfs and other filesystems return
-ENOSYS.
"Some app allocates large tmpfs files, then when some task quits and some
client disconnect, some memory can be released. However the only way to
release tmpfs-swap is to MADV_REMOVE". - Andrea Arcangeli
Databases want to use this feature to drop a section of their bufferpool
(shared memory segments) - without writing back to disk/swap space.
This feature is also useful for supporting hot-plug memory on UML.
Concerns raised by Andrew Morton:
- "We have no plan for holepunching! If we _do_ have such a plan (or
might in the future) then what would the API look like? I think
sys_holepunch(fd, start, len), so we should start out with that."
- Using madvise is very weird, because people will ask "why do I need to
mmap my file before I can stick a hole in it?"
- None of the other madvise operations call into the filesystem in this
manner. A broad question is: is this capability an MM operation or a
filesytem operation? truncate, for example, is a filesystem operation
which sometimes has MM side-effects. madvise is an mm operation and with
this patch, it gains FS side-effects, only they're really, really
significant ones."
Comments:
- Andrea suggested the fs operation too but then it's more efficient to
have it as a mm operation with fs side effects, because they don't
immediatly know fd and physical offset of the range. It's possible to
fixup in userland and to use the fs operation but it's more expensive,
the vmas are already in the kernel and we can use them.
Short term plan & Future Direction:
- We seem to need this interface only for shmfs/tmpfs files in the short
term. We have to add hooks into the filesystem for correctness and
completeness. This is what this patch does.
- In the future, plan is to support both fs and mmap apis also. This
also involves (other) filesystem specific functions to be implemented.
- Current patch doesn't support VM_NONLINEAR - which can be addressed in
the future.
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Andrea Arcangeli <andrea@suse.de>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06 00:10:38 -08:00
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2006-01-09 15:59:24 -08:00
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[PATCH] madvise(MADV_REMOVE): remove pages from tmpfs shm backing store
Here is the patch to implement madvise(MADV_REMOVE) - which frees up a
given range of pages & its associated backing store. Current
implementation supports only shmfs/tmpfs and other filesystems return
-ENOSYS.
"Some app allocates large tmpfs files, then when some task quits and some
client disconnect, some memory can be released. However the only way to
release tmpfs-swap is to MADV_REMOVE". - Andrea Arcangeli
Databases want to use this feature to drop a section of their bufferpool
(shared memory segments) - without writing back to disk/swap space.
This feature is also useful for supporting hot-plug memory on UML.
Concerns raised by Andrew Morton:
- "We have no plan for holepunching! If we _do_ have such a plan (or
might in the future) then what would the API look like? I think
sys_holepunch(fd, start, len), so we should start out with that."
- Using madvise is very weird, because people will ask "why do I need to
mmap my file before I can stick a hole in it?"
- None of the other madvise operations call into the filesystem in this
manner. A broad question is: is this capability an MM operation or a
filesytem operation? truncate, for example, is a filesystem operation
which sometimes has MM side-effects. madvise is an mm operation and with
this patch, it gains FS side-effects, only they're really, really
significant ones."
Comments:
- Andrea suggested the fs operation too but then it's more efficient to
have it as a mm operation with fs side effects, because they don't
immediatly know fd and physical offset of the range. It's possible to
fixup in userland and to use the fs operation but it's more expensive,
the vmas are already in the kernel and we can use them.
Short term plan & Future Direction:
- We seem to need this interface only for shmfs/tmpfs files in the short
term. We have to add hooks into the filesystem for correctness and
completeness. This is what this patch does.
- In the future, plan is to support both fs and mmap apis also. This
also involves (other) filesystem specific functions to be implemented.
- Current patch doesn't support VM_NONLINEAR - which can be addressed in
the future.
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Andrea Arcangeli <andrea@suse.de>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06 00:10:38 -08:00
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2006-01-09 15:59:24 -08:00
|
|
|
|
[PATCH] madvise(MADV_REMOVE): remove pages from tmpfs shm backing store
Here is the patch to implement madvise(MADV_REMOVE) - which frees up a
given range of pages & its associated backing store. Current
implementation supports only shmfs/tmpfs and other filesystems return
-ENOSYS.
"Some app allocates large tmpfs files, then when some task quits and some
client disconnect, some memory can be released. However the only way to
release tmpfs-swap is to MADV_REMOVE". - Andrea Arcangeli
Databases want to use this feature to drop a section of their bufferpool
(shared memory segments) - without writing back to disk/swap space.
This feature is also useful for supporting hot-plug memory on UML.
Concerns raised by Andrew Morton:
- "We have no plan for holepunching! If we _do_ have such a plan (or
might in the future) then what would the API look like? I think
sys_holepunch(fd, start, len), so we should start out with that."
- Using madvise is very weird, because people will ask "why do I need to
mmap my file before I can stick a hole in it?"
- None of the other madvise operations call into the filesystem in this
manner. A broad question is: is this capability an MM operation or a
filesytem operation? truncate, for example, is a filesystem operation
which sometimes has MM side-effects. madvise is an mm operation and with
this patch, it gains FS side-effects, only they're really, really
significant ones."
Comments:
- Andrea suggested the fs operation too but then it's more efficient to
have it as a mm operation with fs side effects, because they don't
immediatly know fd and physical offset of the range. It's possible to
fixup in userland and to use the fs operation but it's more expensive,
the vmas are already in the kernel and we can use them.
Short term plan & Future Direction:
- We seem to need this interface only for shmfs/tmpfs files in the short
term. We have to add hooks into the filesystem for correctness and
completeness. This is what this patch does.
- In the future, plan is to support both fs and mmap apis also. This
also involves (other) filesystem specific functions to be implemented.
- Current patch doesn't support VM_NONLINEAR - which can be addressed in
the future.
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Andrea Arcangeli <andrea@suse.de>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06 00:10:38 -08:00
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2006-07-10 04:44:22 -07:00
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[PATCH] madvise(MADV_REMOVE): remove pages from tmpfs shm backing store
Here is the patch to implement madvise(MADV_REMOVE) - which frees up a
given range of pages & its associated backing store. Current
implementation supports only shmfs/tmpfs and other filesystems return
-ENOSYS.
"Some app allocates large tmpfs files, then when some task quits and some
client disconnect, some memory can be released. However the only way to
release tmpfs-swap is to MADV_REMOVE". - Andrea Arcangeli
Databases want to use this feature to drop a section of their bufferpool
(shared memory segments) - without writing back to disk/swap space.
This feature is also useful for supporting hot-plug memory on UML.
Concerns raised by Andrew Morton:
- "We have no plan for holepunching! If we _do_ have such a plan (or
might in the future) then what would the API look like? I think
sys_holepunch(fd, start, len), so we should start out with that."
- Using madvise is very weird, because people will ask "why do I need to
mmap my file before I can stick a hole in it?"
- None of the other madvise operations call into the filesystem in this
manner. A broad question is: is this capability an MM operation or a
filesytem operation? truncate, for example, is a filesystem operation
which sometimes has MM side-effects. madvise is an mm operation and with
this patch, it gains FS side-effects, only they're really, really
significant ones."
Comments:
- Andrea suggested the fs operation too but then it's more efficient to
have it as a mm operation with fs side effects, because they don't
immediatly know fd and physical offset of the range. It's possible to
fixup in userland and to use the fs operation but it's more expensive,
the vmas are already in the kernel and we can use them.
Short term plan & Future Direction:
- We seem to need this interface only for shmfs/tmpfs files in the short
term. We have to add hooks into the filesystem for correctness and
completeness. This is what this patch does.
- In the future, plan is to support both fs and mmap apis also. This
also involves (other) filesystem specific functions to be implemented.
- Current patch doesn't support VM_NONLINEAR - which can be addressed in
the future.
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Andrea Arcangeli <andrea@suse.de>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06 00:10:38 -08:00
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2006-09-25 23:31:22 -07:00
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2005-04-16 15:20:36 -07:00
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2006-09-25 23:31:22 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: split page table lock
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with
a many-threaded application which concurrently initializes different parts of
a large anonymous area.
This patch corrects that, by using a separate spinlock per page table page, to
guard the page table entries in that page, instead of using the mm's single
page_table_lock. (But even then, page_table_lock is still used to guard page
table allocation, and anon_vma allocation.)
In this implementation, the spinlock is tucked inside the struct page of the
page table page: with a BUILD_BUG_ON in case it overflows - which it would in
the case of 32-bit PA-RISC with spinlock debugging enabled.
Splitting the lock is not quite for free: another cacheline access. Ideally,
I suppose we would use split ptlock only for multi-threaded processes on
multi-cpu machines; but deciding that dynamically would have its own costs.
So for now enable it by config, at some number of cpus - since the Kconfig
language doesn't support inequalities, let preprocessor compare that with
NR_CPUS. But I don't think it's worth being user-configurable: for good
testing of both split and unsplit configs, split now at 4 cpus, and perhaps
change that to 8 later.
There is a benefit even for singly threaded processes: kswapd can be attacking
one part of the mm while another part is busy faulting.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:40 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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[PATCH] Swapless page migration: add R/W migration entries
Implement read/write migration ptes
We take the upper two swapfiles for the two types of migration ptes and define
a series of macros in swapops.h.
The VM is modified to handle the migration entries. migration entries can
only be encountered when the page they are pointing to is locked. This limits
the number of places one has to fix. We also check in copy_pte_range and in
mprotect_pte_range() for migration ptes.
We check for migration ptes in do_swap_cache and call a function that will
then wait on the page lock. This allows us to effectively stop all accesses
to apge.
Migration entries are created by try_to_unmap if called for migration and
removed by local functions in migrate.c
From: Hugh Dickins <hugh@veritas.com>
Several times while testing swapless page migration (I've no NUMA, just
hacking it up to migrate recklessly while running load), I've hit the
BUG_ON(!PageLocked(p)) in migration_entry_to_page.
This comes from an orphaned migration entry, unrelated to the current
correctly locked migration, but hit by remove_anon_migration_ptes as it
checks an address in each vma of the anon_vma list.
Such an orphan may be left behind if an earlier migration raced with fork:
copy_one_pte can duplicate a migration entry from parent to child, after
remove_anon_migration_ptes has checked the child vma, but before it has
removed it from the parent vma. (If the process were later to fault on this
orphaned entry, it would hit the same BUG from migration_entry_wait.)
This could be fixed by locking anon_vma in copy_one_pte, but we'd rather
not. There's no such problem with file pages, because vma_prio_tree_add
adds child vma after parent vma, and the page table locking at each end is
enough to serialize. Follow that example with anon_vma: add new vmas to the
tail instead of the head.
(There's no corresponding problem when inserting migration entries,
because a missed pte will leave the page count and mapcount high, which is
allowed for. And there's no corresponding problem when migrating via swap,
because a leftover swap entry will be correctly faulted. But the swapless
method has no refcounting of its entries.)
From: Ingo Molnar <mingo@elte.hu>
pte_unmap_unlock() takes the pte pointer as an argument.
From: Hugh Dickins <hugh@veritas.com>
Several times while testing swapless page migration, gcc has tried to exec
a pointer instead of a string: smells like COW mappings are not being
properly write-protected on fork.
The protection in copy_one_pte looks very convincing, until at last you
realize that the second arg to make_migration_entry is a boolean "write",
and SWP_MIGRATION_READ is 30.
Anyway, it's better done like in change_pte_range, using
is_write_migration_entry and make_migration_entry_read.
From: Hugh Dickins <hugh@veritas.com>
Remove unnecessary obfuscation from sys_swapon's range check on swap type,
which blew up causing memory corruption once swapless migration made
MAX_SWAPFILES no longer 2 ^ MAX_SWAPFILES_SHIFT.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
From: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 02:03:35 -07:00
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2006-07-14 00:24:37 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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2006-07-14 00:24:37 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-30 01:55:45 -07:00
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2005-04-16 15:20:36 -07:00
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2006-07-14 00:24:37 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-10-29 18:16:15 -07:00
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2005-05-16 21:53:50 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:05 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] can_share_swap_page: use page_mapcount
Remember that ironic get_user_pages race? when the raised page_count on a
page swapped out led do_wp_page to decide that it had to copy on write, so
substituted a different page into userspace. 2.6.7 onwards have Andrea's
solution, where try_to_unmap_one backs out if it finds page_count raised.
Which works, but is unsatisfying (rmap.c has no other page_count heuristics),
and was found a few months ago to hang an intensive page migration test. A
year ago I was hesitant to engage page_mapcount, now it seems the right fix.
So remove the page_count hack from try_to_unmap_one; and use activate_page in
unuse_mm when dropping lock, to replace its secondary effect of helping
swapoff to make progress in that case.
Simplify can_share_swap_page (now called only on anonymous pages) to check
page_mapcount + page_swapcount == 1: still needs the page lock to stabilize
their (pessimistic) sum, but does not need swapper_space.tree_lock for that.
In do_swap_page, move swap_free and unlock_page below page_add_anon_rmap, to
keep sum on the high side, and correct when can_share_swap_page called.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-21 17:15:12 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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2005-05-16 21:53:50 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-05-16 21:53:50 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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2005-11-28 14:34:23 -08:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
|
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|
[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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2006-01-06 00:11:12 -08:00
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2005-10-29 18:16:12 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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[PATCH] mm: split page table lock
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with
a many-threaded application which concurrently initializes different parts of
a large anonymous area.
This patch corrects that, by using a separate spinlock per page table page, to
guard the page table entries in that page, instead of using the mm's single
page_table_lock. (But even then, page_table_lock is still used to guard page
table allocation, and anon_vma allocation.)
In this implementation, the spinlock is tucked inside the struct page of the
page table page: with a BUILD_BUG_ON in case it overflows - which it would in
the case of 32-bit PA-RISC with spinlock debugging enabled.
Splitting the lock is not quite for free: another cacheline access. Ideally,
I suppose we would use split ptlock only for multi-threaded processes on
multi-cpu machines; but deciding that dynamically would have its own costs.
So for now enable it by config, at some number of cpus - since the Kconfig
language doesn't support inequalities, let preprocessor compare that with
NR_CPUS. But I don't think it's worth being user-configurable: for good
testing of both split and unsplit configs, split now at 4 cpus, and perhaps
change that to 8 later.
There is a benefit even for singly threaded processes: kswapd can be attacking
one part of the mm while another part is busy faulting.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:40 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-10-29 18:16:12 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
|
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|
[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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|
[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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|
[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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|
[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
|
|
|
|
[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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2006-09-25 23:30:57 -07:00
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2005-04-16 15:20:36 -07:00
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2005-11-29 16:55:48 +00:00
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2005-04-16 15:20:36 -07:00
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[PATCH] page fault retry with NOPAGE_REFAULT
Add a way for a no_page() handler to request a retry of the faulting
instruction. It goes back to userland on page faults and just tries again
in get_user_pages(). I added a cond_resched() in the loop in that later
case.
The problem I have with signal and spufs is an actual bug affecting apps and I
don't see other ways of fixing it.
In addition, we are having issues with infiniband and 64k pages (related to
the way the hypervisor deals with some HV cards) that will require us to muck
around with the MMU from within the IB driver's no_page() (it's a pSeries
specific driver) and return to the caller the same way using NOPAGE_REFAULT.
And to add to this, the graphics folks have been following a new approach of
memory management that involves transparently swapping objects between video
ram and main meory. To do that, they need installing PTEs from a no_page()
handler as well and that also requires returning with NOPAGE_REFAULT.
(For the later, they are currently using io_remap_pfn_range to install one PTE
from no_page() which is a bit racy, we need to add a check for the PTE having
already been installed afer taking the lock, but that's ok, they are only at
the proof-of-concept stage. I'll send a patch adding a "clean" function to do
that, we can use that from spufs too and get rid of the sparsemem hacks we do
to create struct page for SPEs. Basically, that provides a generic solution
for being able to have no_page() map hardware devices, which is something that
I think sound driver folks have been asking for some time too).
All of these things depend on having the NOPAGE_REFAULT exit path from
no_page() handlers.
Signed-off-by: Benjamin Herrenchmidt <benh@kernel.crashing.org>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-06 00:43:53 -07:00
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2005-04-16 15:20:36 -07:00
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|
[PATCH] page fault retry with NOPAGE_REFAULT
Add a way for a no_page() handler to request a retry of the faulting
instruction. It goes back to userland on page faults and just tries again
in get_user_pages(). I added a cond_resched() in the loop in that later
case.
The problem I have with signal and spufs is an actual bug affecting apps and I
don't see other ways of fixing it.
In addition, we are having issues with infiniband and 64k pages (related to
the way the hypervisor deals with some HV cards) that will require us to muck
around with the MMU from within the IB driver's no_page() (it's a pSeries
specific driver) and return to the caller the same way using NOPAGE_REFAULT.
And to add to this, the graphics folks have been following a new approach of
memory management that involves transparently swapping objects between video
ram and main meory. To do that, they need installing PTEs from a no_page()
handler as well and that also requires returning with NOPAGE_REFAULT.
(For the later, they are currently using io_remap_pfn_range to install one PTE
from no_page() which is a bit racy, we need to add a check for the PTE having
already been installed afer taking the lock, but that's ok, they are only at
the proof-of-concept stage. I'll send a patch adding a "clean" function to do
that, we can use that from spufs too and get rid of the sparsemem hacks we do
to create struct page for SPEs. Basically, that provides a generic solution
for being able to have no_page() map hardware devices, which is something that
I think sound driver folks have been asking for some time too).
All of these things depend on having the NOPAGE_REFAULT exit path from
no_page() handlers.
Signed-off-by: Benjamin Herrenchmidt <benh@kernel.crashing.org>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-06 00:43:53 -07:00
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2005-04-16 15:20:36 -07:00
|
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|
[PATCH] page fault retry with NOPAGE_REFAULT
Add a way for a no_page() handler to request a retry of the faulting
instruction. It goes back to userland on page faults and just tries again
in get_user_pages(). I added a cond_resched() in the loop in that later
case.
The problem I have with signal and spufs is an actual bug affecting apps and I
don't see other ways of fixing it.
In addition, we are having issues with infiniband and 64k pages (related to
the way the hypervisor deals with some HV cards) that will require us to muck
around with the MMU from within the IB driver's no_page() (it's a pSeries
specific driver) and return to the caller the same way using NOPAGE_REFAULT.
And to add to this, the graphics folks have been following a new approach of
memory management that involves transparently swapping objects between video
ram and main meory. To do that, they need installing PTEs from a no_page()
handler as well and that also requires returning with NOPAGE_REFAULT.
(For the later, they are currently using io_remap_pfn_range to install one PTE
from no_page() which is a bit racy, we need to add a check for the PTE having
already been installed afer taking the lock, but that's ok, they are only at
the proof-of-concept stage. I'll send a patch adding a "clean" function to do
that, we can use that from spufs too and get rid of the sparsemem hacks we do
to create struct page for SPEs. Basically, that provides a generic solution
for being able to have no_page() map hardware devices, which is something that
I think sound driver folks have been asking for some time too).
All of these things depend on having the NOPAGE_REFAULT exit path from
no_page() handlers.
Signed-off-by: Benjamin Herrenchmidt <benh@kernel.crashing.org>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-06 00:43:53 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-23 02:03:43 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-23 02:03:43 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:05 -07:00
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2005-04-16 15:20:36 -07:00
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2006-01-06 00:11:12 -08:00
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2005-11-21 21:32:19 -08:00
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2005-10-29 18:16:05 -07:00
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2005-04-16 15:20:36 -07:00
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2006-09-25 23:30:57 -07:00
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2005-10-29 18:16:05 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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|
[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2006-09-25 23:30:57 -07:00
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2006-09-25 23:30:58 -07:00
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2006-09-25 23:30:57 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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2006-09-27 01:50:10 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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|
[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
|
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|
[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: split page table lock
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with
a many-threaded application which concurrently initializes different parts of
a large anonymous area.
This patch corrects that, by using a separate spinlock per page table page, to
guard the page table entries in that page, instead of using the mm's single
page_table_lock. (But even then, page_table_lock is still used to guard page
table allocation, and anon_vma allocation.)
In this implementation, the spinlock is tucked inside the struct page of the
page table page: with a BUILD_BUG_ON in case it overflows - which it would in
the case of 32-bit PA-RISC with spinlock debugging enabled.
Splitting the lock is not quite for free: another cacheline access. Ideally,
I suppose we would use split ptlock only for multi-threaded processes on
multi-cpu machines; but deciding that dynamically would have its own costs.
So for now enable it by config, at some number of cpus - since the Kconfig
language doesn't support inequalities, let preprocessor compare that with
NR_CPUS. But I don't think it's worth being user-configurable: for good
testing of both split and unsplit configs, split now at 4 cpus, and perhaps
change that to 8 later.
There is a benefit even for singly threaded processes: kswapd can be attacking
one part of the mm while another part is busy faulting.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:40 -07:00
|
|
|
|
[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
|
[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-10-29 18:16:12 -07:00
|
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|
|
[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:23 -07:00
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2005-04-16 15:20:36 -07:00
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|
[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
|
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2005-10-29 18:16:48 -07:00
|
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|
|
[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:48 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2006-09-27 01:50:10 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: split page table lock
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with
a many-threaded application which concurrently initializes different parts of
a large anonymous area.
This patch corrects that, by using a separate spinlock per page table page, to
guard the page table entries in that page, instead of using the mm's single
page_table_lock. (But even then, page_table_lock is still used to guard page
table allocation, and anon_vma allocation.)
In this implementation, the spinlock is tucked inside the struct page of the
page table page: with a BUILD_BUG_ON in case it overflows - which it would in
the case of 32-bit PA-RISC with spinlock debugging enabled.
Splitting the lock is not quite for free: another cacheline access. Ideally,
I suppose we would use split ptlock only for multi-threaded processes on
multi-cpu machines; but deciding that dynamically would have its own costs.
So for now enable it by config, at some number of cpus - since the Kconfig
language doesn't support inequalities, let preprocessor compare that with
NR_CPUS. But I don't think it's worth being user-configurable: for good
testing of both split and unsplit configs, split now at 4 cpus, and perhaps
change that to 8 later.
There is a benefit even for singly threaded processes: kswapd can be attacking
one part of the mm while another part is busy faulting.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:40 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:48 -07:00
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[PATCH] mm: page fault handler locking
On the page fault path, the patch before last pushed acquiring the
page_table_lock down to the head of handle_pte_fault (though it's also taken
and dropped earlier when a new page table has to be allocated).
Now delete that line, read "entry = *pte" without it, and go off to this or
that page fault handler on the basis of this unlocked peek. Usually the
handler can proceed without the lock, relying on the subsequent locked
pte_same or pte_none test to back out when necessary; though do_wp_page needs
the lock immediately, and do_file_page doesn't check (if there's a race,
install_page just zaps the entry and reinstalls it).
But on those architectures (notably i386 with PAE) whose pte is too big to be
read atomically, if SMP or preemption is enabled, do_swap_page and
do_file_page might cause irretrievable damage if passed a Frankenstein entry
stitched together from unrelated parts. In those configs, "pte_unmap_same"
has to take page_table_lock, validate orig_pte still the same, and drop
page_table_lock before unmapping, before proceeding.
Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
avoidance leaves more lone maps and unmaps than elsewhere.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:26 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: page fault handlers tidyup
Impose a little more consistency on the page fault handlers do_wp_page,
do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their
arguments in the same order, called the same names?
break_cow is all very well, but what it did was inlined elsewhere: easier to
compare if it's brought back into do_wp_page.
do_file_page's fallback to do_no_page dates from a time when we were testing
pte_file by using it wherever possible: currently it's peculiar to nonlinear
vmas, so just check that. BUG_ON if not? Better not, it's probably page
table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's
use that for do_wp_page's invalid pfn too.
Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it:
restored (and say "pud" not "pmd" in its pud_ERROR).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:15:59 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-30 01:55:45 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-20 16:24:28 +01:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:23 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:23 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:23 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:23 -07:00
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2005-04-16 15:20:36 -07:00
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2005-11-15 15:53:48 -05:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: init_mm without ptlock
First step in pushing down the page_table_lock. init_mm.page_table_lock has
been used throughout the architectures (usually for ioremap): not to serialize
kernel address space allocation (that's usually vmlist_lock), but because
pud_alloc,pmd_alloc,pte_alloc_kernel expect caller holds it.
Reverse that: don't lock or unlock init_mm.page_table_lock in any of the
architectures; instead rely on pud_alloc,pmd_alloc,pte_alloc_kernel to take
and drop it when allocating a new one, to check lest a racing task already
did. Similarly no page_table_lock in vmalloc's map_vm_area.
Some temporary ugliness in __pud_alloc and __pmd_alloc: since they also handle
user mms, which are converted only by a later patch, for now they have to lock
differently according to whether or not it's init_mm.
If sources get muddled, there's a danger that an arch source taking
init_mm.page_table_lock will be mixed with common source also taking it (or
neither take it). So break the rules and make another change, which should
break the build for such a mismatch: remove the redundant mm arg from
pte_alloc_kernel (ppc64 scrapped its distinct ioremap_mm in 2.6.13).
Exceptions: arm26 used pte_alloc_kernel on user mm, now pte_alloc_map; ia64
used pte_alloc_map on init_mm, now pte_alloc_kernel; parisc had bad args to
pmd_alloc and pte_alloc_kernel in unused USE_HPPA_IOREMAP code; ppc64
map_io_page forgot to unlock on failure; ppc mmu_mapin_ram and ppc64 im_free
took page_table_lock for no good reason.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:21 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:22 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:23 -07:00
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2005-10-29 18:16:22 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: init_mm without ptlock
First step in pushing down the page_table_lock. init_mm.page_table_lock has
been used throughout the architectures (usually for ioremap): not to serialize
kernel address space allocation (that's usually vmlist_lock), but because
pud_alloc,pmd_alloc,pte_alloc_kernel expect caller holds it.
Reverse that: don't lock or unlock init_mm.page_table_lock in any of the
architectures; instead rely on pud_alloc,pmd_alloc,pte_alloc_kernel to take
and drop it when allocating a new one, to check lest a racing task already
did. Similarly no page_table_lock in vmalloc's map_vm_area.
Some temporary ugliness in __pud_alloc and __pmd_alloc: since they also handle
user mms, which are converted only by a later patch, for now they have to lock
differently according to whether or not it's init_mm.
If sources get muddled, there's a danger that an arch source taking
init_mm.page_table_lock will be mixed with common source also taking it (or
neither take it). So break the rules and make another change, which should
break the build for such a mismatch: remove the redundant mm arg from
pte_alloc_kernel (ppc64 scrapped its distinct ioremap_mm in 2.6.13).
Exceptions: arm26 used pte_alloc_kernel on user mm, now pte_alloc_map; ia64
used pte_alloc_map on init_mm, now pte_alloc_kernel; parisc had bad args to
pmd_alloc and pte_alloc_kernel in unused USE_HPPA_IOREMAP code; ppc64
map_io_page forgot to unlock on failure; ppc mmu_mapin_ram and ppc64 im_free
took page_table_lock for no good reason.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:21 -07:00
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2005-10-29 18:16:22 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:22 -07:00
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2005-10-29 18:16:23 -07:00
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2005-10-29 18:16:22 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] Workaround for gcc 2.96 (undefined references)
LD .tmp_vmlinux1
mm/built-in.o(.text+0x100d6): In function `copy_page_range':
: undefined reference to `__pud_alloc'
mm/built-in.o(.text+0x1010b): In function `copy_page_range':
: undefined reference to `__pmd_alloc'
mm/built-in.o(.text+0x11ef4): In function `__handle_mm_fault':
: undefined reference to `__pud_alloc'
fs/built-in.o(.text+0xc930): In function `install_arg_page':
: undefined reference to `__pud_alloc'
make: *** [.tmp_vmlinux1] Error 1
Those missing references in mm/memory.c arise from this code in
include/linux/mm.h, combined with the fact that __PGTABLE_PMD_FOLDED and
__PGTABLE_PUD_FOLDED are both set and __ARCH_HAS_4LEVEL_HACK is not:
/*
* The following ifdef needed to get the 4level-fixup.h header to work.
* Remove it when 4level-fixup.h has been removed.
*/
#if defined(CONFIG_MMU) && !defined(__ARCH_HAS_4LEVEL_HACK)
static inline pud_t *pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
{
return (unlikely(pgd_none(*pgd)) && __pud_alloc(mm, pgd, address))?
NULL: pud_offset(pgd, address);
}
static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
{
return (unlikely(pud_none(*pud)) && __pmd_alloc(mm, pud, address))?
NULL: pmd_offset(pud, address);
}
#endif /* CONFIG_MMU && !__ARCH_HAS_4LEVEL_HACK */
With my configuration the pgd_none and pud_none routines are inlines
returning a constant 0. Apparently the old compiler avoids generating
calls to __pud_alloc and __pmd_alloc but still lists them as undefined
references in the module's symbol table.
I don't know which change caused this problem. I think it was added
somewhere between 2.6.14 and 2.6.15-rc1, because I remember building
several 2.6.14-rc kernels without difficulty. However I can't point to an
individual culprit.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-28 13:43:44 -08:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: init_mm without ptlock
First step in pushing down the page_table_lock. init_mm.page_table_lock has
been used throughout the architectures (usually for ioremap): not to serialize
kernel address space allocation (that's usually vmlist_lock), but because
pud_alloc,pmd_alloc,pte_alloc_kernel expect caller holds it.
Reverse that: don't lock or unlock init_mm.page_table_lock in any of the
architectures; instead rely on pud_alloc,pmd_alloc,pte_alloc_kernel to take
and drop it when allocating a new one, to check lest a racing task already
did. Similarly no page_table_lock in vmalloc's map_vm_area.
Some temporary ugliness in __pud_alloc and __pmd_alloc: since they also handle
user mms, which are converted only by a later patch, for now they have to lock
differently according to whether or not it's init_mm.
If sources get muddled, there's a danger that an arch source taking
init_mm.page_table_lock will be mixed with common source also taking it (or
neither take it). So break the rules and make another change, which should
break the build for such a mismatch: remove the redundant mm arg from
pte_alloc_kernel (ppc64 scrapped its distinct ioremap_mm in 2.6.13).
Exceptions: arm26 used pte_alloc_kernel on user mm, now pte_alloc_map; ia64
used pte_alloc_map on init_mm, now pte_alloc_kernel; parisc had bad args to
pmd_alloc and pte_alloc_kernel in unused USE_HPPA_IOREMAP code; ppc64
map_io_page forgot to unlock on failure; ppc mmu_mapin_ram and ppc64 im_free
took page_table_lock for no good reason.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:21 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:22 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:23 -07:00
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2005-10-29 18:16:22 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] mm: init_mm without ptlock
First step in pushing down the page_table_lock. init_mm.page_table_lock has
been used throughout the architectures (usually for ioremap): not to serialize
kernel address space allocation (that's usually vmlist_lock), but because
pud_alloc,pmd_alloc,pte_alloc_kernel expect caller holds it.
Reverse that: don't lock or unlock init_mm.page_table_lock in any of the
architectures; instead rely on pud_alloc,pmd_alloc,pte_alloc_kernel to take
and drop it when allocating a new one, to check lest a racing task already
did. Similarly no page_table_lock in vmalloc's map_vm_area.
Some temporary ugliness in __pud_alloc and __pmd_alloc: since they also handle
user mms, which are converted only by a later patch, for now they have to lock
differently according to whether or not it's init_mm.
If sources get muddled, there's a danger that an arch source taking
init_mm.page_table_lock will be mixed with common source also taking it (or
neither take it). So break the rules and make another change, which should
break the build for such a mismatch: remove the redundant mm arg from
pte_alloc_kernel (ppc64 scrapped its distinct ioremap_mm in 2.6.13).
Exceptions: arm26 used pte_alloc_kernel on user mm, now pte_alloc_map; ia64
used pte_alloc_map on init_mm, now pte_alloc_kernel; parisc had bad args to
pmd_alloc and pte_alloc_kernel in unused USE_HPPA_IOREMAP code; ppc64
map_io_page forgot to unlock on failure; ppc mmu_mapin_ram and ppc64 im_free
took page_table_lock for no good reason.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 18:16:21 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:22 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:22 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:22 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:22 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-29 18:16:23 -07:00
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2005-10-29 18:16:22 -07:00
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[PATCH] Workaround for gcc 2.96 (undefined references)
LD .tmp_vmlinux1
mm/built-in.o(.text+0x100d6): In function `copy_page_range':
: undefined reference to `__pud_alloc'
mm/built-in.o(.text+0x1010b): In function `copy_page_range':
: undefined reference to `__pmd_alloc'
mm/built-in.o(.text+0x11ef4): In function `__handle_mm_fault':
: undefined reference to `__pud_alloc'
fs/built-in.o(.text+0xc930): In function `install_arg_page':
: undefined reference to `__pud_alloc'
make: *** [.tmp_vmlinux1] Error 1
Those missing references in mm/memory.c arise from this code in
include/linux/mm.h, combined with the fact that __PGTABLE_PMD_FOLDED and
__PGTABLE_PUD_FOLDED are both set and __ARCH_HAS_4LEVEL_HACK is not:
/*
* The following ifdef needed to get the 4level-fixup.h header to work.
* Remove it when 4level-fixup.h has been removed.
*/
#if defined(CONFIG_MMU) && !defined(__ARCH_HAS_4LEVEL_HACK)
static inline pud_t *pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
{
return (unlikely(pgd_none(*pgd)) && __pud_alloc(mm, pgd, address))?
NULL: pud_offset(pgd, address);
}
static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
{
return (unlikely(pud_none(*pud)) && __pmd_alloc(mm, pud, address))?
NULL: pmd_offset(pud, address);
}
#endif /* CONFIG_MMU && !__ARCH_HAS_4LEVEL_HACK */
With my configuration the pgd_none and pud_none routines are inlines
returning a constant 0. Apparently the old compiler avoids generating
calls to __pud_alloc and __pmd_alloc but still lists them as undefined
references in the module's symbol table.
I don't know which change caused this problem. I think it was added
somewhere between 2.6.14 and 2.6.15-rc1, because I remember building
several 2.6.14-rc kernels without difficulty. However I can't point to an
individual culprit.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-28 13:43:44 -08:00
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2005-04-16 15:20:36 -07:00
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2006-03-26 18:30:52 +02:00
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2005-04-16 15:20:36 -07:00
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2005-09-10 00:26:28 -07:00
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2005-04-16 15:20:36 -07:00
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[PATCH] unpaged: VM_UNPAGED
Although we tend to associate VM_RESERVED with remap_pfn_range, quite a few
drivers set VM_RESERVED on areas which are then populated by nopage. The
PageReserved removal in 2.6.15-rc1 changed VM_RESERVED not to free pages in
zap_pte_range, without changing those drivers not to set it: so their pages
just leak away.
Let's not change miscellaneous drivers now: introduce VM_UNPAGED at the core,
to flag the special areas where the ptes may have no struct page, or if they
have then it's not to be touched. Replace most instances of VM_RESERVED in
core mm by VM_UNPAGED. Force it on in remap_pfn_range, and the sparc and
sparc64 io_remap_pfn_range.
Revert addition of VM_RESERVED to powerpc vdso, it's not needed there. Is it
needed anywhere? It still governs the mm->reserved_vm statistic, and special
vmas not to be merged, and areas not to be core dumped; but could probably be
eliminated later (the drivers are probably specifying it because in 2.4 it
kept swapout off the vma, but in 2.6 we work from the LRU, which these pages
don't get on).
Use the VM_SHM slot for VM_UNPAGED, and define VM_SHM to 0: it serves no
purpose whatsoever, and should be removed from drivers when we clean up.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: William Irwin <wli@holomorphy.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-21 21:32:15 -08:00
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2005-04-16 15:20:36 -07:00
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2006-09-27 01:50:15 -07:00
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