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Author SHA1 Message Date
SJ Park
d59bf2653c mm/damon/core: handle unreset probe_hits in probe_hits_mvsum() 
If damon_update_monitoring_result() is called at the end of the
aggregation interval, probe_hits is not reset.  That's because the value
will be exposed to the user via damon_region_aggregated trace event.

Meanwhile, damon_probe_hits_mvsum() can be called in this state.  Due to
its logic, it will return a value that is incorrectly high.  This could
happen if the user requested DAMOS schemes applied regions sysfs files
update exactly in the time sequence.

The impact is minor, but better to avoid.  Check the timing and simply
return the fully aggregated last_probe_hits, like
damon_nr_accesses_mvsum() also does.  It is not 100% accurate since it is
the last interval's aggregation.  But better than the value that is
completely reset.

Link: https://lore.kernel.org/20260708135359.122587-8-sj@kernel.org
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:44 -07:00
SJ Park
e06b7f0cf8 mm/damon/core: update probe hits for new parameter commit 
Users can update DAMON parameters at runtime.  If the samples and/or
aggregation intervals are updated in this way, monitoring results
depending on the intervals should also be updated for a more accurate
snapshot.  The age and nr_accesses are properly updated, while probe_hits
are not updated in the way.  Do the update.

Link: https://lore.kernel.org/20260708135359.122587-7-sj@kernel.org
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:44 -07:00
SJ Park
84113a30a8 mm/damon/core: s/nr_accesses_for_new_attrs/nr_samples_for_new_attrs/ 
damon_nr_accesses_for_new_attrs() can be used for not only nr_accesses but
also any positive sample count, like probe_hits.  Rename to be able to be
used for such general uses without confusion.

Link: https://lore.kernel.org/20260708135359.122587-6-sj@kernel.org
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:44 -07:00
SJ Park
f9088c9845 mm/damon/core: s/nr_accesses_to_accesses_bp/sample_count_to_bp/ 
damon_nr_accesses_to_accesses_bp() actually converts a positive sample
count to the ratio.  Rename it to better describe what it really does and
not confusing for more general uses.

Link: https://lore.kernel.org/20260708135359.122587-5-sj@kernel.org
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:43 -07:00
SJ Park
71599dc253 mm/damon/core: s/accesses_bp_to_nr_accesses/sample_bp_to_count/ 
accesses_bp_to_nr_accesses() actually converts a positive samples ratio to
the count.  Rename it to better describe what it really does and not
confusing for more general uses.

Link: https://lore.kernel.org/20260708135359.122587-4-sj@kernel.org
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:43 -07:00
SJ Park
571cc9a34e mm/damon/core: s/damon_max_nr_accesses()/damon_nr_samples_per_aggr()/ 
damon_max_nr_accesses() actually returns the number of samples DAMON
checks for each region per each aggregation interval.  Rename it to better
describe what it really does and not confusing for more general uses.

Link: https://lore.kernel.org/20260708135359.122587-3-sj@kernel.org
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:43 -07:00
SJ Park
f3ab162a92 mm/damon/core: remove comment and test for nr_to_bp() divide-by-zero 
Patch series "mm/damon: update probe hits for runtime parameter commits".

DAMON users can update DAMON parameters such as sampling and aggregation
intervals at runtime.  For such changes, monitoring results that depend on
the intervals should be properly updated for better accuracy.  For
example, the access frequency counter (nr_accesses) is updated.  The data
attribute monitoring counter (probe_hits) is not being updated, though. 
Do the updates for new parameters.

Patch 1 removes obsolete comments and test code for a function that this
series will touch.  Patches 2-5 rename functions that are being used for
nr_accesses update, to be able to be used for probe_hits without
confusion.  Patch 6 does the probe_hits update.  Patch 7 update
damon_probe_hits_mvsum() to cover a corner case from the update for better
accuracy.


This patch (of 7):

The comments on damon_nr_accesses_to_accesses_bp() and its unit test warn
it can trigger division-by-zero when the aggregation interval is zero. 
Commit 35d4a3cf70 ("mm/damon/ops-common: handle extreme intervals in
damon_hot_score()") modified damon_max_nr_accesses() to always return
non-zero.  Hence no division-by-zero of the note can happen.  Remove the
obsolete comment on the function.  The test code was written to test the
division-by-zero case, which cannot happen anymore.  Having it makes no
sense.  Entirely remove the test code and its comment.

Link: https://lore.kernel.org/20260708135359.122587-1-sj@kernel.org
Link: https://lore.kernel.org/20260708135359.122587-2-sj@kernel.org
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:43 -07:00
David Hildenbrand (Arm)
3b7cee2e9a mm/bootmem_info: remove CONFIG_HAVE_BOOTMEM_INFO_NODE 
The whole infrastructure is unused now. Let's remove the config option
along with mm/bootmem_info. + include/linux/bootmem_info.h.

Link: https://lore.kernel.org/20260716-bootmem_info_part2-v2-10-4afc76c73d61@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:42 -07:00
David Hildenbrand (Arm)
4f9ec35df5 mm/sparse: remove bootmem_info.h include 
No longer required, so let's remove it.

Link: https://lore.kernel.org/20260716-bootmem_info_part2-v2-9-4afc76c73d61@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:42 -07:00
David Hildenbrand (Arm)
788a0efb95 mm/hugetlb_vmemmap: remove bootmem_info leftovers 
We never set CONFIG_HAVE_BOOTMEM_INFO_NODE, so we can just switch to
free_reserved_page() and drop the register_page_bootmem_memmap() call.

Link: https://lore.kernel.org/20260716-bootmem_info_part2-v2-8-4afc76c73d61@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:42 -07:00
David Hildenbrand (Arm)
ea963eab11 x86/mm: remove CONFIG_HAVE_BOOTMEM_INFO_NODE 
CONFIG_HAVE_BOOTMEM_INFO_NODE now essentially doesn't do anything.

So let's remove support for CONFIG_HAVE_BOOTMEM_INFO_NODE.

Link: https://lore.kernel.org/20260716-bootmem_info_part2-v2-7-4afc76c73d61@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:42 -07:00
David Hildenbrand (Arm)
f20e92095f x86/mm: stop marking page tables as MIX_SECTION_INFO 
There is no good reason to mark boot page tables as MIX_SECTION_INFO: we
only free boot page tables when they are completely empty, and memory
offlining/hotunplug doesn't benefit from it in any way.

So just stop marking page tables as MIX_SECTION_INFO.  In
free_pagetable(), we can now simply free reserved pages directly.

Link: https://lore.kernel.org/20260716-bootmem_info_part2-v2-6-4afc76c73d61@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:41 -07:00
David Hildenbrand (Arm)
7bfc04d6bd x86/mm: stop marking vmemmap as SECTION_INFO 
We added the whole bootmem registration machinery in commit 0475327876
("memory hotplug: register section/node id to free").

The main use case was to remember to which memory section memmap pages
belonged, so the memmap could be handled accordingly when freeing memory.

However, all that machinery is not required anymore: a memory section can
only get offlined if *all* pages can get offlined; and it can only get
unplugged once offline.  If some of these pages are unmovable memmap
pages: bad luck, doesn't work.  Offlining will fail.

Further, a lot of this machinery was required for pre-vmemmap support. 
Now we only support the vmemmap with memory hotplug.

So the whole machinery is useless today.  Let's start by removing the last
pieces by first stopping to mark vmemmap pages as SECTION_INFO.  In
free_vmemmap_pages(), we can now always just free the reserved pages
directly.

Link: https://lore.kernel.org/20260716-bootmem_info_part2-v2-5-4afc76c73d61@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:41 -07:00
David Hildenbrand (Arm)
f4436442e5 mm/bootmem_info: allow calling free_bootmem_page() on pages without a bootmem_type 
As preparation for further changes, let's temporarily allow freeing pages
that were not previously registered.

This will allow freeing unregistered vmemmap pages allocated during boot
through free_bootmem_page() from hugetlb code, until we fully rip all of
that out.

Link: https://lore.kernel.org/20260716-bootmem_info_part2-v2-4-4afc76c73d61@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:41 -07:00
David Hildenbrand (Arm)
cbbd561893 s390/mm: use free_reserved_pages() in vmem_free_pages() 
Let's use our new generic helper.

Link: https://lore.kernel.org/20260716-bootmem_info_part2-v2-3-4afc76c73d61@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:41 -07:00
David Hildenbrand (Arm)
d79db3f396 mm: provide free_reserved_pages(), removing x86 variant 
Let's extend free_reserved_page() in page_alloc.c to
free_reserved_pages(), dropping the custom x86 variant.  The common-code
variant will consume an order, so adjust the x86 callers accordingly.

Make free_reserved_pages() assume that we are freeing ordinary high-order
pages, just with the special "reserved" flavor.  The target use case for
now is freeing vmemmap PMD pages.

Set the refcount directly to 0 (instead of 1) and call
__free_frozen_pages().  Set the page count to 0 before clearing
PG_reserved, so someone checking PG_reserved (and not finding it set) to
then try grabbing a ref would not suddenly have that ref be dropped.  That
is arguably cleaner and safer than the old way of doing it.

Add some kerneldoc.  Use a single adjust_managed_page_count() call.

Link: https://lore.kernel.org/20260716-bootmem_info_part2-v2-2-4afc76c73d61@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:40 -07:00
David Hildenbrand (Arm)
5e83b4944d x86/mm: drop order parameter from free_pagetable() 
Patch series "mm: remove CONFIG_HAVE_BOOTMEM_INFO_NODE (Part 2)", v2.

Let's remove the remaining pieces of CONFIG_HAVE_BOOTMEM_INFO_NODE,
performing some smaller cleanups around freeing of reserved vmemmap pages
on the way.


This patch (of 10):

All callers pass 0, so let's drop the parameter.

Link: https://lore.kernel.org/20260716-bootmem_info_part2-v2-0-4afc76c73d61@kernel.org
Link: https://lore.kernel.org/20260716-bootmem_info_part2-v2-1-4afc76c73d61@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:40 -07:00
Hajime Tazaki
324853ce8d mm: nommu: fix the error path when vma_iter_prealloc() fails 
When vma_iter_prealloc() fails in do_mmap(), it jumps to error_just_free
as a error path of this function, but there are several possible issues.

1) It jumps to error_just_free without updating ret to -ENOMEM, meaning
   do_mmap() will return 0 on failure.

2) The error path unconditionally frees the region struct.  Since the
   region was already added to the global nommu_region_tree via
   add_nommu_region(), leaving it makes a potential dangling pointer in
   the tree and may cause a use-after-free on the next tree walk.

3) If do_mmap() finds an existing overlapping shared region, it
   increments its usage, sets region to this existing pregion, and jumps
   to share:

	region = pregion;
	result = start;
	goto share;

   When vma_iter_prealloc() fails and jumps to error_just_free, the
   error path unconditionally frees the region:

error:
	...
	if (region->vm_file)
		fput(region->vm_file);
	kmem_cache_free(vm_region_jar, region);

   This potentially leaves a dangling pointer in nommu_region_tree and
   causes RB-tree corruption.

4) When establishing a new private mapping, do_mmap_private() allocates
   physical pages and assigns them to region->vm_start:

	base = alloc_pages_exact(total << PAGE_SHIFT, GFP_KERNEL);
	...
	region->vm_start = (unsigned long) base;

   If we later fail at vma_iter_prealloc() and jump to error_just_free,
   the region struct is freed, but the backing physical memory isn't freed
   via free_page_series().

5) In the error label of do_mmap(), the vm_area_struct allocated is
   freed by vm_area_free(vma) but not called after vma_close(), leaving
   potential memory leak which should be handled by a custom .close
   handler of vm_ops.

This commit fixes those issues by introducing new jump label,
error_vma_iter_prealloc, to correctly handle the error case of
vma_iter_prealloc(), updating ret value (1), and move the region updates
after the place that the allocation is finished (2).

Additionally, the commit removes the existing goto label, error, and
consolidates to error_just_free as existing `goto error;` code blocks
always release nommu_region_sem.

Moreover, it only frees region allocated in this request to avoid
freeing the shared, existing region shared by other processes (3), and
free physical memory when do_mmap_private() allocates (4). It also add
vma_close() before vm_area_free() to fix the potential leak (5).

Those issues are discovered by Sashiko, linked below.

Link: https://lore.kernel.org/20260708083829.576036-1-thehajime@gmail.com
Link: https://sashiko.dev/#/patchset/20260702012830.667205-1-thehajime%40gmail.com
Link: https://sashiko.dev/#/patchset/c8513ee5aa8444ec9bf6c276043c9f833016a2fa.1783304131.git.thehajime%40gmail.com
Link: https://sashiko.dev/#/patchset/20260707235137.498738-1-thehajime%40gmail.com
Fixes: b5df092264 ("mm: set up vma iterator for vma_iter_prealloc() calls")
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:40 -07:00
Kiryl Shutsemau (Meta)
a137d9f8f5 Documentation/userfaultfd: document RWP working set tracking 
Add an admin-guide section covering UFFDIO_REGISTER_MODE_RWP:

  - sync and async fault models;
  - UFFDIO_RWPROTECT semantics;
  - UFFD_FEATURE_RWP_ASYNC;
  - UFFDIO_SET_MODE runtime mode flips.

It also covers typical VMM working-set-tracking workflow from detection
loop through sync-mode eviction and back to async.

Link: https://lore.kernel.org/20260708111417.173443-16-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Assisted-by: Claude:claude-opus-4-6
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: James Houghton <jthoughton@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: kernel test robot <lkp@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:40 -07:00
Kiryl Shutsemau (Meta)
3628215f7f selftests/mm: add userfaultfd RWP tests 
Coverage for UFFDIO_REGISTER_MODE_RWP and UFFDIO_RWPROTECT:

  rwp-async          async mode — touch pages, verify permissions are
                     auto-restored without a message
  rwp-sync           sync mode — access blocks, handler resolves via
                     UFFDIO_RWPROTECT
  rwp-pagemap        PAGEMAP_SCAN reports still-cold pages via
                     inverted PAGE_IS_ACCESSED
  rwp-mprotect       RWP survives mprotect(PROT_NONE) ->
                     mprotect(PROT_READ|PROT_WRITE) round-trip
  rwp-gup            GUP walks through a protnone RWP PTE (pipe
                     write/read drives the GUP path)
  rwp-async-toggle   UFFDIO_SET_MODE flips between sync and async
                     without re-registering
  rwp-close          closing the uffd restores page permissions
  rwp-fork           RWP survives fork() with EVENT_FORK; child's
                     PTEs keep the uffd bit
  rwp-fork-pin       RWP survives fork() on an RO-longterm-pinned
                     anon page (forces copy_present_page()); child
                     read auto-resolves and clears the bit, proving
                     PAGE_NONE was in place
  rwp-wp-exclusive   register with MODE_WP|MODE_RWP returns -EINVAL

All tests run against anon, shmem, shmem-private, hugetlb, and
hugetlb-private memory, except rwp-fork-pin which is anon-only —
copy_present_page() is the private-anon pinned-exclusive fork path.

Snapshot the RWP additions into tools/include/uapi/linux/userfaultfd.h so
the selftest builds without requiring "make headers" first, matching the
mechanism established by commit 580ea358af ("selftests/mm: fix
additional build errors for selftests").

Link: https://lore.kernel.org/ak-Z9KO2mP9HMOPW@thinkstation
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Assisted-by: Claude:claude-opus-4-6
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: James Houghton <jthoughton@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:39 -07:00
Kiryl Shutsemau (Meta)
39a7c34ea5 userfaultfd: add UFFDIO_SET_MODE for runtime sync/async toggle 
Add an ioctl to toggle async mode at runtime without re-registering the
userfaultfd.  This allows a VMM to switch between sync and async RWP modes
on-the-fly -- for example, starting in async mode for working set
scanning, then switching to sync mode to intercept faults during page
eviction.

UFFDIO_SET_MODE takes an enable/disable bitmask of UFFD_FEATURE_* flags. 
Only UFFD_FEATURE_RWP_ASYNC is toggleable today; the ioctl rejects any
other bit with -EINVAL.  Enabling RWP_ASYNC also requires RWP to have been
negotiated at UFFDIO_API time, mirroring the UFFDIO_API invariant.

Fault-path readers of ctx->features run under mmap_read_lock or a per-VMA
lock; the RMW takes mmap_write_lock and calls vma_start_write() on every
UFFD-armed VMA, so those readers are fully excluded. 
userfaultfd_show_fdinfo(), however, reads ctx->features without any lock,
so the RMW is written as a single WRITE_ONCE and fdinfo reads it with
READ_ONCE.  That keeps the lockless observer from seeing a mid-RMW
intermediate and removes the audit burden when new toggleable bits are
added later.

When switching to async, pending sync waiters are woken so they retry and
auto-resolve under the new mode.

Link: https://lore.kernel.org/20260708111417.173443-14-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Assisted-by: Claude:claude-opus-4-6
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: James Houghton <jthoughton@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:39 -07:00
Kiryl Shutsemau (Meta)
45347e3d32 userfaultfd: add UFFD_FEATURE_RWP_ASYNC for async fault resolution 
Sync RWP delivers a message and blocks the faulting thread until the
handler resolves the fault.  For working-set tracking the VMM does not
need the message: it just needs to know, at scan time, which pages were
touched.  Async RWP serves that use case — the kernel restores access
in-place and the faulting thread continues without blocking.

The VMM reconstructs the access pattern after the fact via PAGEMAP_SCAN:
pages whose uffd bit is still set (inverted PAGE_IS_ACCESSED) were not
re-accessed since the last RWP cycle.

Worth calling out: async resolution upgrades writable private anon PTEs
via pte_mkwrite() when can_change_pte_writable() allows, mirroring
do_numa_page().  Without it, every re-access of an RWP'd writable page
would COW-fault a second time.

UFFD_FEATURE_RWP_ASYNC requires UFFD_FEATURE_RWP.

Link: https://lore.kernel.org/20260708111417.173443-13-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Assisted-by: Claude:claude-opus-4-6
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: James Houghton <jthoughton@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:39 -07:00
Kiryl Shutsemau (Meta)
3389648819 mm/pagemap: add PAGE_IS_ACCESSED for RWP tracking 
PAGEMAP_SCAN already reports PAGE_IS_WRITTEN from the inverted uffd PTE
bit, targeting the UFFDIO_WRITEPROTECT workflow.  UFFDIO_RWPROTECT reuses
the same PTE bit as a marker for read-write protection, but "has been
written" and "has been accessed" are distinct semantic signals — they
happen to share one PTE bit today only because the two implementations
share infrastructure.

Give RWP its own pagemap category so the UAPI does not conflate them:

  PAGE_IS_WRITTEN   reported on VM_UFFD_WP VMAs,  !pte_uffd(pte)
  PAGE_IS_ACCESSED  reported on VM_UFFD_RWP VMAs, !pte_uffd(pte)

Both still read the same PTE bit today, but each is scoped to the VMA
whose registered mode makes the bit meaningful.  If a future
implementation moves RWP to a separate PTE bit, only PAGE_IS_ACCESSED
switches over.

This is a UAPI narrowing.  Outside VM_UFFD_WP VMAs the uffd bit is always
clear, so PAGEMAP_SCAN used to flag PAGE_IS_WRITTEN on every present PTE
there — a meaningless duplicate of PAGE_IS_PRESENT.  Now PAGE_IS_WRITTEN
fires only inside VM_UFFD_WP VMAs.

pagemap_hugetlb_category() now takes the vma like its PTE/PMD peers.

Link: https://lore.kernel.org/20260708111417.173443-12-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Assisted-by: Claude:claude-opus-4-6
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: James Houghton <jthoughton@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:38 -07:00
Kiryl Shutsemau (Meta)
2d427bb016 mm/userfaultfd: add RWP fault delivery and expose UFFDIO_REGISTER_MODE_RWP 
Wire the fault side of read-write protection tracking and turn the
userspace interface on.

An RWP-protected PTE is PAGE_NONE with the uffd bit set.  The PROT_NONE
triggers a fault on any access; the uffd bit distinguishes it from plain
mprotect(PROT_NONE) or NUMA hinting.

Fault dispatch, per level:

  PTE     handle_pte_fault()    -> do_uffd_rwp()
  PMD     __handle_mm_fault()   -> do_huge_pmd_uffd_rwp()
  hugetlb hugetlb_fault()       -> hugetlb_handle_userfault()

The RWP branches gate on userfaultfd_pte_rwp() /
userfaultfd_huge_pmd_rwp() (VM_UFFD_RWP plus the uffd bit) and fall
through to do_numa_page() / do_huge_pmd_numa_page() otherwise.  Each
delivers a UFFD_PAGEFAULT_FLAG_RWP message through handle_userfault(); the
handler resolves it with UFFDIO_RWPROTECT clearing MODE_RWP.

userfaultfd_must_wait() and userfaultfd_huge_must_wait() add matching
protnone+uffd waiters so sync-mode fault handlers block correctly.

Expose the UAPI:

  UFFDIO_REGISTER_MODE_RWP   -> UFFD_API_REGISTER_MODES
  UFFD_FEATURE_RWP           -> UFFD_API_FEATURES
  _UFFDIO_RWPROTECT          -> UFFD_API_RANGE_IOCTLS
                                UFFD_API_RANGE_IOCTLS_BASIC

UFFD_FEATURE_RWP is masked out at UFFDIO_API time when PROT_NONE is not
available or VM_UFFD_RWP aliases VM_NONE (32-bit), so userspace never sees
an advertised-but-broken feature.

Works on anonymous, shmem, and hugetlb memory.

Link: https://lore.kernel.org/20260708111417.173443-11-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Assisted-by: Claude:claude-opus-4-6
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: James Houghton <jthoughton@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:38 -07:00
Kiryl Shutsemau (Meta)
6eab8f2cc6 userfaultfd: add UFFDIO_REGISTER_MODE_RWP and UFFDIO_RWPROTECT plumbing 
Add the userspace interface for read-write protection tracking:

  - UFFDIO_REGISTER_MODE_RWP      register a range for RWP tracking
  - UFFD_FEATURE_RWP              capability bit
  - UFFDIO_RWPROTECT              install / remove RWP on a range

Introduce CONFIG_USERFAULTFD_RWP, auto-selected on 64-bit kernels with
ARCH_HAS_PTE_PROTNONE and HAVE_ARCH_USERFAULTFD_WP.  The symbol gates
VM_UFFD_RWP (previously aliased to VM_NONE) and the smaps/trace-flag hooks
added in the preparatory patches; without it the UAPI bits added here have
nothing to drive and would be unreachable.

Registration sets VM_UFFD_RWP on the VMA.  Combining MODE_WP with MODE_RWP
is rejected because both modes claim the uffd PTE bit.

UFFDIO_RWPROTECT is the bidirectional counterpart of
UFFDIO_WRITEPROTECT:

  - MODE_RWP              change_protection() with MM_CP_UFFD_RWP
                          installs PAGE_NONE and sets the uffd bit on
                          present PTEs
  - !MODE_RWP             change_protection() with MM_CP_UFFD_RWP_RESOLVE
                          restores vma->vm_page_prot and clears the bit

userfaultfd_clear_vma() runs the same resolve pass on unregister so RWP
state cannot outlive the uffd.

Re-registering a range must not drop a mode that installs per-PTE markers
(WP or RWP); doing so returns -EBUSY.  This also closes a pre-existing
window where re-registering without MODE_WP would strand uffd-wp markers:
before, those caused extra write-faults but were otherwise benign; with
RWP preservation in place, a subsequent mprotect() on a VM_UFFD_RWP VMA
would silently promote the stale markers to RWP.

The feature is not yet advertised.  UFFDIO_REGISTER_MODE_RWP,
UFFD_FEATURE_RWP, and _UFFDIO_RWPROTECT are intentionally absent from
UFFD_API_REGISTER_MODES, UFFD_API_FEATURES, and UFFD_API_RANGE_IOCTLS, so
UFFDIO_API masks them out and the register-mode validator rejects the bit.
The follow-up patch adds fault dispatch and exposes the UAPI.

Link: https://lore.kernel.org/20260708111417.173443-10-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Assisted-by: Claude:claude-opus-4-6
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: James Houghton <jthoughton@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:38 -07:00
Kiryl Shutsemau (Meta)
7974c23853 mm: handle VM_UFFD_RWP in khugepaged, rmap, and GUP 
Three mm paths outside the fault handler gate on the uffd PTE bit today:
khugepaged (skip collapse on ranges carrying markers), rmap (cap unmap
batching), and GUP (force a fault through gup_can_follow_protnone). 
Extend each to treat VM_UFFD_RWP the same as VM_UFFD_WP; otherwise per-PTE
RWP state is silently destroyed or bypassed.

khugepaged: try_collapse_pte_mapped_thp() and
file_backed_vma_is_retractable() already refuse to collapse or retract
page tables on ranges carrying the uffd PTE bit.  Broaden the VMA
predicate from userfaultfd_wp() to userfaultfd_protected() so VM_UFFD_RWP
ranges get the same protection.  hpage_collapse_scan_pmd() needs no change
— its existing pte_uffd() check already catches an RWP PTE because it
carries the uffd bit.

rmap: folio_unmap_pte_batch() caps batching at 1 for VM_UFFD_RWP so the
restore path handles each PTE with its own marker.

GUP: gup_can_follow_protnone() forces a fault on VM_UFFD_RWP VMAs
regardless of FOLL_HONOR_NUMA_FAULT.  RWP uses protnone as an
access-tracking marker, not for NUMA hinting, so any GUP — read or write
— must go through the userfaultfd fault path.

Link: https://lore.kernel.org/20260708111417.173443-9-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Assisted-by: Claude:claude-opus-4-6
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: James Houghton <jthoughton@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:38 -07:00
Kiryl Shutsemau (Meta)
763f43865f mm: preserve RWP marker across PTE rewrites 
The uffd PTE bit must survive any kernel path that rewrites a PTE on a
VM_UFFD_RWP VMA, otherwise the marker that carries PAGE_NONE semantics is
silently dropped and the next access leaks past RWP tracking.  Wire the
preservation through every path that rewrites a VM_UFFD_RWP PTE.

Swap and device-exclusive: do_swap_page(), restore_exclusive_pte(), and
unuse_pte() (swapoff()) re-apply PAGE_NONE when the swap PTE carries the
uffd bit and the VMA has VM_UFFD_RWP.

Migration: remove_migration_pte() and remove_migration_pmd() do the same
after the migration entry is replaced with a real PTE/PMD.

Fork: __copy_present_ptes(), copy_present_page(), copy_nonpresent_pte(),
copy_huge_pmd(), copy_huge_non_present_pmd(), and
copy_hugetlb_page_range() keep the uffd bit on the child when the
destination VMA has VM_UFFD_RWP, matching the existing VM_UFFD_WP
handling.  Add VM_UFFD_RWP to VM_COPY_ON_FORK so the flag itself
propagates.

mprotect(): change_pte_range() and change_huge_pmd() restore PAGE_NONE
after pte_modify()/pmd_modify() have recomputed the base protection from a
(possibly user-changed) vm_page_prot.  pte_modify() preserves _PAGE_UFFD,
so the bit stays; we just have to force PAGE_NONE back on top.

Link: https://lore.kernel.org/20260708111417.173443-8-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Assisted-by: Claude:claude-opus-4-6
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: James Houghton <jthoughton@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:37 -07:00
Kiryl Shutsemau (Meta)
9cf3c554ac mm: add MM_CP_UFFD_RWP change_protection() flag 
Preparatory patch.  Add the change_protection() primitive that userfaultfd
RWP will use.

An RWP-protected PTE is PAGE_NONE with the uffd PTE bit set.  The
PROT_NONE half makes the CPU fault on any access; the uffd bit
distinguishes an RWP fault from a plain mprotect(PROT_NONE) or NUMA
hinting fault.  MM_CP_UFFD_WP and MM_CP_UFFD_RWP share the same PTE bit,
so the two cannot be used together on the same range.

Two new change_protection() flags:

  MM_CP_UFFD_RWP            install PAGE_NONE and set the uffd bit
  MM_CP_UFFD_RWP_RESOLVE    restore vma->vm_page_prot, clear the uffd bit

Both are wired through change_pte_range(), change_huge_pmd(), and
hugetlb_change_protection() so anon, shmem, THP, and hugetlb all share the
same semantics.

Link: https://lore.kernel.org/20260708111417.173443-7-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Assisted-by: Claude:claude-opus-4-6
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: James Houghton <jthoughton@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:37 -07:00
Kiryl Shutsemau (Meta)
134c1d031a mm: add VM_UFFD_RWP VMA flag 
Preparatory patch for userfaultfd read-write protection (RWP).  RWP
extends userfaultfd protection from plain write-protection (WP) to full
read-write protection: accesses to an RWP-protected range -- reads as well
as writes -- trap through userfaultfd.

Reserve VM_UFFD_RWP, add the userfaultfd_rwp() and userfaultfd_protected()
helpers, and wire up the smaps "ur" entry and the trace-flag table the
rest of the series will use.  The flag is gated on CONFIG_USERFAULTFD_RWP,
which is introduced together with the UAPI in a later patch; until then
VM_UFFD_RWP aliases VM_NONE and every downstream check folds to dead code.

Nothing sets or queries the flag yet.

Link: https://lore.kernel.org/20260708111417.173443-6-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Assisted-by: Claude:claude-opus-4-6
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: James Houghton <jthoughton@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:37 -07:00
Kiryl Shutsemau (Meta)
2730ee209f userfaultfd: test uffd VMA flags through the vma_flags_t API 
The uffd VMA-flag helpers read vma->vm_flags directly.  Now that
config-gated per-mode masks exist, switch them to the vma_flags_t accessor
vma_test_any_mask(), which is the going-forward API and keeps a single
place (the VMA_UFFD_* masks) that knows which modes are available on the
current build.

No functional change: vma_flags_t is in union with vm_flags, so the same
bits are read, and the masks fold to the same code the open-coded vm_flags
tests produced -- verified identical on gcc and clang, 32- and 64-bit.

Link: https://lore.kernel.org/20260708111417.173443-5-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Suggested-by: Lorenzo Stoakes <ljs@kernel.org>
Assisted-by: Claude:claude-opus-4-8
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: James Houghton <jthoughton@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:36 -07:00
Kiryl Shutsemau (Meta)
c0ffe79eed mm: rename uffd-wp PTE accessors to uffd 
Userfaultfd RWP will reuse the uffd-wp PTE bit to mark access-tracking
PTEs, alongside the write-protected ones it already marks.  The bit's
meaning now depends on the VMA flag (WP or RWP), not on its name.

Rename the kernel-internal names that describe the bit:

  - pte/pmd/huge_pte accessors (and swap variants)
  - pgtable_supports_uffd() capability query
  - SCAN_PTE_UFFD khugepaged enum

The ftrace string emitted by mm_khugepaged_scan_pmd for this enum is
kept as "pte_uffd_wp" so existing trace-based tooling keeps matching.

Pure mechanical rename -- no behavior change.

Link: https://lore.kernel.org/20260708111417.173443-4-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Assisted-by: Claude:claude-opus-4-6
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: James Houghton <jthoughton@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:36 -07:00
Kiryl Shutsemau (Meta)
2bd507795e mm: rename uffd-wp PTE bit macros to uffd 
The uffd-wp PTE bit is about to gain a second consumer: userfaultfd RWP
will use the same bit to mark access-tracking PTEs, distinct from
mprotect(PROT_NONE) or NUMA-hinting PTEs.  WP vs RWP semantics come from
the VMA flag; the bit is just "uffd has claimed this entry." Drop the
"_wp" suffix from the arch-private bit macros so they reflect that.

  x86:   _PAGE_BIT_UFFD_WP  -> _PAGE_BIT_UFFD
         _PAGE_UFFD_WP      -> _PAGE_UFFD
         _PAGE_SWP_UFFD_WP  -> _PAGE_SWP_UFFD
  arm64: PTE_UFFD_WP        -> PTE_UFFD
         PTE_SWP_UFFD_WP    -> PTE_SWP_UFFD
  riscv: _PAGE_UFFD_WP      -> _PAGE_UFFD
         _PAGE_SWP_UFFD_WP  -> _PAGE_SWP_UFFD

Pure mechanical rename -- no behavior change.

Link: https://lore.kernel.org/20260708111417.173443-3-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Assisted-by: Claude:claude-opus-4-6
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: James Houghton <jthoughton@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:36 -07:00
Kiryl Shutsemau (Meta)
c6f11553c0 mm: decouple protnone helpers from CONFIG_NUMA_BALANCING 
Patch series "userfaultfd: working set tracking for VM guest memory", v10.

This series adds userfaultfd support for tracking the working set of VM
guest memory, so a VMM can identify hot pages and reclaim cold ones to
tiered or remote storage.


This patch (of 15):

pte_protnone() and pmd_protnone() detect present-but-inaccessible page
table entries.  This capability is useful beyond NUMA balancing -- for
example, userfaultfd working set tracking uses protnone PTEs to track page
access without unmapping pages.

Introduce CONFIG_ARCH_HAS_PTE_PROTNONE to decouple the protnone PTE
infrastructure from CONFIG_NUMA_BALANCING.  The six architectures that
support protnone PTEs (x86_64, arm64, powerpc, s390, riscv, loongarch) now
select this option, and CONFIG_NUMA_BALANCING depends on it.

No functional change -- the same set of architectures continues to have
working protnone support, but the infrastructure is now available
independently of NUMA balancing.

Link: https://lore.kernel.org/20260708111417.173443-1-kirill@shutemov.name
Link: https://lore.kernel.org/20260708111417.173443-2-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Assisted-by: Claude:claude-opus-4-6
Acked-by: SeongJae Park <sj@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: James Houghton <jthoughton@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:36 -07:00
Jaeyeon Lee
889d3783ae mm/shmem: annotate benign data-race in shmem_getattr() 
shmem_getattr() reads info->alloced, info->swapped and i_mapping->nrpages
without info->lock to decide whether shmem_recalc_inode() should be
called.  shmem_recalc_inode() recomputes these under info->lock, so a
stale read here only affects whether shmem_recalc_inode() runs.

Annotate data_race() to silence KCSAN.

Link: https://lore.kernel.org/20260708111941.35460-1-jaeyeon.lee.dev@gmail.com
Signed-off-by: Jaeyeon Lee <jaeyeon.lee.dev@gmail.com>
Reported-by: syzbot+dfb578404df369f6599b@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=dfb578404df369f6599b
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:35 -07:00
Jianyue Wu
3fe0620fae mm: move reclaim-internal declarations out of swap.h 
Keep include/linux/swap.h focused on swap-facing interfaces by moving
MM-internal reclaim and workingset declarations into mm/internal.h.

Leave the small set of LRU helper declarations that are used outside mm/
in swap.h so this cleanup does not need a new public header under
include/linux/.

Link: https://lore.kernel.org/20260708-ch-swap-series-plus-folio-lru-cleanup-v9-3-2bc72b4f8730@gmail.com
Signed-off-by: Jianyue Wu <wujianyue000@gmail.com>
Suggested-by: Barry Song <baohua@kernel.org>
Suggested-by: Baoquan He <bhe@redhat.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:35 -07:00
Jianyue Wu
0ba14428ab mm: rename swap.c to folio.c 
Rename mm/swap.c to mm/folio.c so the filename better matches the code's
main responsibility.

This keeps the implementation split from swap-specific code without
changing the published LRU helper interfaces.

Update MAINTAINERS and the remaining mm/swap.c documentation references
after the rename.

[wujianyue000@gmail.com: MAINTAINERS: move mm/folio.c to MM CORE]
  Link: https://lore.kernel.org/20260804111109.393127-1-wujianyue000@gmail.com
Link: https://lore.kernel.org/20260708-ch-swap-series-plus-folio-lru-cleanup-v9-2-2bc72b4f8730@gmail.com
Signed-off-by: Jianyue Wu <wujianyue000@gmail.com>
Suggested-by: Baoquan He <bhe@redhat.com>
Suggested-by: David Hildenbrand <david@kernel.org>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chris Li <chrisl@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:35 -07:00
Jianyue Wu
2253208bec mm/swap: colocate page-cluster sysctl with swap readahead 
Patch series "mm: clean up folio LRU and swap declarations", v9.

This series splits folio LRU and swap cleanup into three steps:

  - move the page-cluster sysctl next to swap readahead in
    mm/swap_state.c
  - rename mm/swap.c to mm/folio.c after the swap-specific code
    moves out
  - move MM-internal reclaim declarations out of include/linux/swap.h

After this series, swap cache and swap-in readahead stay in
mm/swap_state.c.  Folio LRU helpers live in mm/folio.c, and MM-internal
reclaim/workingset declarations move from include/linux/swap.h to
mm/internal.h (public LRU helpers used outside mm/ remain in swap.h).

The first patch handles the swap-specific page-cluster state before the
file rename, so the rename commit only carries folio LRU code.  The last
patch keeps the LRU helpers used outside mm/ in include/linux/swap.h and
moves the internal reclaim/workingset declarations to mm/internal.h.


This patch (of 3):

page_cluster and the vm.page-cluster sysctl are only used by swap-in
readahead in swap_state.c.  Move them out of swap.c together with
swap_readahead_setup(), and make page_cluster static to that file.

Rename swap_setup() while moving it as well.  The helper is internal to MM
and now only sets up swap readahead defaults and its sysctl hook, so the
more specific name matches its reduced scope.

Call swap_readahead_setup() from swap_init() after moving it, keeping the
readahead defaults and sysctl registration with swap_state.c
initialization.

swap_setup() previously lived in mm/swap.c, which is built
unconditionally, so the vm.page-cluster sysctl was registered also on
CONFIG_SWAP=n kernels.  After moving the setup into swap_state.c, which is
built only when CONFIG_SWAP is enabled, vm.page-cluster is no longer
registered there.  The knob only tunes swap-in readahead and had no effect
without swap.

Link: https://lore.kernel.org/20260708-ch-swap-series-plus-folio-lru-cleanup-v9-0-2bc72b4f8730@gmail.com
Link: https://lore.kernel.org/20260708-ch-swap-series-plus-folio-lru-cleanup-v9-1-2bc72b4f8730@gmail.com
Signed-off-by: Jianyue Wu <wujianyue000@gmail.com>
Suggested-by: Baoquan He <bhe@redhat.com>
Suggested-by: Barry Song <baohua@kernel.org>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Kairui Song <kasong@tencent.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:34 -07:00
Barry Song (Xiaomi)
3cedb745d3 mm: clarify the folio_free_swap() for do_swap_page() 
Since commit 4b34f1d82c ("mm, swap: free the swap cache after folio is
mapped"), we have relied on do_wp_page() to handle the non-exclusive case,
where the folio may either be reused or require CoW.

As a result, using the refcount in do_swap_page() to decide when to free
the swap cache is no longer necessary, since do_wp_page() can handle this
more cleanly and consistently.

We can now simply use FAULT_FLAG_WRITE together with exclusivity to decide
when to free the swap cache in do_swap_page().

Link: https://lore.kernel.org/20260701235955.36126-5-baohua@kernel.org
Signed-off-by: Barry Song (Xiaomi) <baohua@kernel.org>
Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Usama Arif <usama.arif@linux.dev>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:34 -07:00
Barry Song (Xiaomi)
38f380f143 mm: entirely remove lru_add_drain in do_swap_page 
We are doing a lot of redundant lru_add_drain() calls in do_swap_page(),
especially for synchronous I/O devices.  For example, the test program
below currently ends up draining lru_cache 100% of the time:

int main(int argc, char *argv[])
{
        int i;
 #define SIZE 100*1024*1024
	while(1) {
		volatile int *p = mmap(0, SIZE, PROT_READ | PROT_WRITE,
                        MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

		for (int i = 0; i < SIZE/sizeof(int); i++)
			p[i] =  i%64;
		madvise((void *)p, SIZE, MADV_PAGEOUT);
		for (int i = 0; i < SIZE/sizeof(int); i++)
			p[i] =  i%64;
		munmap(p, SIZE);
	}
	return 0;
}

Folio reuse now relies primarily on the exclusive hint, making lru_cache
draining to drop the refcount in lru_cache largely irrelevant.  For a
kernel build with a minimal configuration running in a 1 GB memcg, this
patch skips more than 43,000 redundant local LRU drains.

Link: https://lore.kernel.org/20260701235955.36126-4-baohua@kernel.org
Signed-off-by: Barry Song (Xiaomi) <baohua@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Usama Arif <usama.arif@linux.dev>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:34 -07:00
Barry Song (Xiaomi)
34f6c8932e mm: drop stale folio_ref_count()==1 check in do_swap_page reuse logic 
The "we just allocated them without exposing them to the swapcache" case
no longer exists, as Kairui has routed synchronous I/O through the
swapcache as well in his series "unify swapin use swap cache and cleanup
flags"[1].  As a result, folio_ref_count() should never be 1 in this path,
since at least two references are held (base ref plus swapcache).  Remove
the folio_ref_count()==1 check and update the comment accordingly.

The ksm_might_need_to_copy() check may allocate a fresh folio with
folio_ref_count() == 1.  Along that path, exclusive has already been
set to true, so the folio can still be reused correctly.

[akpm@linux-foundation.org: update comment, per David]
  Link: https://lore.kernel.org/3a185a5d-2f2c-4e9d-9cd9-8bdb236dfc5c@kernel.org
Link: https://lore.kernel.org/20260701235955.36126-3-baohua@kernel.org
Link: https://lore.kernel.org/all/20251220-swap-table-p2-v5-0-8862a265a033@tencent.com/ [1]
Signed-off-by: Barry Song (Xiaomi) <baohua@kernel.org>
Acked-by: Usama Arif <usama.arif@linux.dev>
Reviewed-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Baoquan He <baoquan.he@linux.dev>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Chris Li <chrisl@kernel.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:34 -07:00
Barry Song (Xiaomi)
8d596d8b81 mm: avoid unnecessary lru drain for wp_can_reuse_anon_folio() 
Patch series "mm: drop redundant lru_add_drain in anon folio reuse paths",
v3.

We are doing a large number of redundant lru_add_drain() calls in both
wp_can_reuse_anon_folio() and do_swap_page(), leading to LRU lock
contention and unnecessary overhead.

In wp_can_reuse_anon_folio(), we can check the refcount against the
lru_cache before deciding to drain.  In do_swap_page(), the drain is now
entirely redundant after Kairui's work to route SYNC I/O through the
swapcache in the same way as ASYNC I/O.

Build the kernel within a 1 GB memcg using 20 threads with zRAM swap.  The
number of lru_add_drain() calls is reduced from 276,278 to 226,318, a
reduction of about 18%.

Build the kernel within an 800 MB memcg using 20 threads with zRAM swap. 
The number of lru_add_drain() calls is reduced from 778,950 to 541,149, a
reduction of 30.5%.


This patch (of 4):

There is a case where `folio_ref_count(folio) == 3` and
`!folio_test_swapcache(folio)`. In that case, both
`folio_ref_count(folio) > 3` and
`folio_ref_count(folio) > 1 + folio_test_swapcache(folio)` evaluate
false, causing an unnecessary local LRU drain.

During an Ubuntu boot, I observed over 5,000 redundant local LRU drains. 
For a kernel build with a minimal configuration, I observed more than
20,000 redundant drains.

Fix this by checking against: `1 + in_swapcache + in_lrucache` instead of
hardcoding `folio_ref_count(folio) > 3`.

[baohua@kernel.org: rename in_lru_cache to maybe_in_lru_cache]
  Link: https://lore.kernel.org/20260708145718.82690-1-baohua@kernel.org
Link: https://lore.kernel.org/20260701235955.36126-1-baohua@kernel.org
Link: https://lore.kernel.org/20260701235955.36126-2-baohua@kernel.org
Signed-off-by: Barry Song (Xiaomi) <baohua@kernel.org>
Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Kairui Song <kasong@tencent.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Baoquan He <baoquan.he@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Usama Arif <usama.arif@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:33 -07:00
Zi Yan
819bfbd47e mm/page_alloc: remove set_page_private() in prep_compound_tail() 
Tail pages are expected to have (and optionally be checked) zeroed
->private when they are freed.  It stays true during subsequent
reallocation, so replace the tail_page->private initialization with a
VM_WARN_ON_ONCE() in compound page preparation.

Link: https://lore.kernel.org/20260709-keep-subpage-private-zero-at-free-v3-5-7e4fe155f5b9@nvidia.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:33 -07:00
Zi Yan
04ad9908b0 mm/page_alloc: make sure tail_page->private is zero at page free time 
Any code using tail_page->private of a folio, a compound page or a
high-order page is supposed to reset it after use, otherwise ->private
data can leak to new page user and cause unexpected issues.  Add a
bad_page() check at page free path for it.

Link: https://lore.kernel.org/20260709-keep-subpage-private-zero-at-free-v3-4-7e4fe155f5b9@nvidia.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:33 -07:00
Zi Yan
d007658032 mm/huge_memory: add page->private check back in __split_folio_to_order() 
page->private should not be set in tail pages.  Commit 4265d67e40
("mm/migrate_device: add THP splitting during migration") removed a
DEBUG_VM check without a proper reason[1].  Add it back.

Link: https://lore.kernel.org/all/13f3fcda-7328-4aa5-afc6-75a294a82b2a@nvidia.com/ [1]
Link: https://lore.kernel.org/20260709-keep-subpage-private-zero-at-free-v3-3-7e4fe155f5b9@nvidia.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:33 -07:00
Zi Yan
7ae5a5d8ec mm/compaction: stop recording free page order in page->private 
Commit 733aea0b3a ("mm/compaction: add support for >0 order folio
memory compaction.") stores isolated free pages in an array indexed by
free page orders, it is no longer needed to store the order in each page's
->private field.  And there is no code using the stored order.  Stop doing
that.

It also prepares for an upcoming change that ensures subpage->private is
zero at page free time and the removal of set_page_private(0) from
prep_compound_tail().

Link: https://lore.kernel.org/20260709-keep-subpage-private-zero-at-free-v3-2-7e4fe155f5b9@nvidia.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:32 -07:00
Zi Yan
f283f6a4e1 mm/percpu-km: clear page->private before free them 
Patch series "Keep tail page private zero at free and folio split", v3.

This patchset makes sure tail_page->private is zero before compound or
high-order pages are returned to the allocator.  It also checks tail pages
that become new folio heads during large folio split, before their private
fields are used by new folios.

Note on ZONE_DEVICE and DAX page/folio
===
ZONE_DEVICE and DAX use prep_compound_tail() to reinitialize folios, so
tail_page->private was reset before this patchset.  There was a concern
that after this patchset stale ->private can appear after ZONE_DEVICE/DAX
folio initialization.  My reasoning is that no code sets ZONE_DEVICE/DAX
page->private, so their page->private stays zero all the time. 
ZONE_DEVICE_PRIVATE page migration only supports anonymous memory without
swapcache, so after the migration ->private remains zero.

But let me know if my reasoning is wrong.  It can be fixed by adding
->private zeroing code in ZONE_DEVICE/DAX folio initialization code.

Motivation
===

page->private is zeroed at page free time since commit ac1ea21959
("mm/page_alloc: clear page->private in free_pages_prepare()"), since we
concluded that it might be too much to ask every page user to free a page
with ->private zeroed.  The holder of the last page reference might not
know whether ->private needs to be cleared.

For compound and high-order pages, tail_page->private can also leak to
later users if it is left uncleared.  The page allocation path does not
zero every tail_page->private field, so they can be seen by new users and
cause unexpected issues[1].

Check tail_page->private at page free time, and check tail pages that
become new folio heads during large folio split.  With those checks in
place, prep_compound_tail() no longer needs to clear tail_page->private
when preparing compound page metadata.

Overview
===

1. Patch 1 clears all pages ->private before percpu-km frees them.
2. Patch 2 removes setting page->private in compaction code when a free
   page is taken out of the buddy allocator. cc->freepages is indexed by
   page order, so storing the free page order in page->private is
   redundant. In alloc_contig_frozen_range_noprof(),
   isolate_freepages_range() is used to grab free pages from buddy
   allocator and it leaves the aforementioned page->private set until
   either split_free_frozen_pages() or prep_new_page() is called. That
   stale value without resetting triggers the tail_page->private nonzero
   check once set_page_private(0) is removed from prep_compound_tail().

3. Patch 3 adds back the page->private check for tail pages promoted to new
   folio heads in __split_folio_to_order().
4. Patch 4 adds a tail_page->private check in the page free path.
5. Patch 5 removes tail_page->private zeroing from prep_compound_tail().


This patch (of 5):

page->private is cleared in free page path.  In a subsequent commit,
tail_page->private will be checked and ensured to be zero.  Clearing
percpu-km allocated pages' ->private to prevent triggering warnings later,
namely undo what we did in pcpu_create_chunk().

Link: https://lore.kernel.org/20260709-keep-subpage-private-zero-at-free-v3-0-7e4fe155f5b9@nvidia.com
Link: https://lore.kernel.org/20260709-keep-subpage-private-zero-at-free-v3-1-7e4fe155f5b9@nvidia.com
Link: https://lore.kernel.org/all/20260206174017.128673-1-mikhail.v.gavrilov@gmail.com/ [1]
Signed-off-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:32 -07:00
SJ Park
b1cc60c13b samples/damon/prcl: do not stop DAMON for damon_call() failure 
damon_call() failure was causing the context to be stopped, but
asynchronously by the kdamond thread.  To handle the race, the caller had
to stop the context.  damon_call() is updated to do the stop on its own. 
Remove the damon_stop() call from the damon_call() error handling.

Link: https://lore.kernel.org/20260706140628.87414-12-sj@kernel.org
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:32 -07:00
SJ Park
cfd843b299 samples/damon/wsse: do not stop ctx for damon_call() failure 
damon_call() failure was causing the context to be stopped, but
asynchronously by the kdamond thread.  To handle the race, the caller had
to stop the context.  damon_call() is updated to do the stop on its own. 
Remove the damon_stop() call from the damon_call() error handling.

Link: https://lore.kernel.org/20260706140628.87414-11-sj@kernel.org
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:32 -07:00
SJ Park
d079b6b890 mm/damon/core: wait ctx stop in damon_call() before reruning an error 
damon_call() failure means the DAMON context started its termination.  The
termination is asynchronously done in kdamond thread.  The caller's error
handling should handle the race, too.  It is complicated and easy to make
mistakes.

Update damon_call() to ensure the context is stopped in the case, by
waiting until the completion is confirmed.

Link: https://lore.kernel.org/20260706140628.87414-10-sj@kernel.org
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:31 -07:00
SJ Park
3e734a0514 samples/damon/mtier: stop all contexts with single damon_stop() call 
damon_stop() was theoretically able to return failure while keeping the
second context for mtier running.  mtier stops its contexts one by one
with two damon_stop() call for the reason.  damon_stop() is refactored to
always successfully stop all requested DAMON contexts.  The two calls are
unnecessary.  Use only single damon_stop() call for all contexts.

Link: https://lore.kernel.org/20260706140628.87414-9-sj@kernel.org
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2026-08-04 19:18:31 -07:00