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412 commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Linus Torvalds
|
ed3b875bea |
mm.git review status for mm-hotfixes-stable..mm-stable
Everything:
Total patches: 501
Reviews/patch: 1.66
Reviewed rate: 70%
Excluding DAMON:
Total patches: 356
Reviews/patch: 2.26
Reviewed rate: 90%
Excluding DAMON and selftests:
Total patches: 329
Reviews/patch: 2.31
Reviewed rate: 92%
Excluding DAMON, selftests and maple_tree:
Total patches: 328
Reviews/patch: 2.31
Reviewed rate: 92%
Summary of patch series in this merge:
- The 2 patch series "mm: drop "sub" prefix from various places" from
Dev Jain implements some page->folio conversion and a naming cleanup.
- The 2 patch series "mm/kasan: remove redundant initialization for
kasan_flag_write_only" from Igor Putko provides some KASAN cleanup work.
- The 2 patch series "mm/filemap: reduce unnecessary xarray lookups"
from Chi Zhiling provides a small speedup in the pagecaache read code.
- The 4 patch series "mm/percpu: Fix possible NOFS/NOIO reclaim
recursion" from Kaitao Cheng improves a few things in the vmalloc code -
mainly the avoidance of GFP_KERNEL allocations when the caller asked for
GFP_NOFS or GFP_NOIO.
- The 3 patch series "mm/kmemleak: avoid soft lockup when scanning task
stacks" from Breno Leitao avoids a soft lockup watchdog trigger from the
kmemleak scanning code in extreme situations.
- The 6 patch series "mm/page_owner: misc cleanups" from Ye Liu is a
collection of unrelated cleanups to the page_owner code. For some
reason lots of people have been working on the page_owner code this
cycle.
- The 4 patch series "mm: convert to walk_page_range_vma() to eliminate
find_vma()" from Kefeng Wang simplifies and accelerates the page walking
library function.
- The 3 patch series "mm/migrate: preparatory cleanups for batch copy
and offload" from Shivank Garg implements cleanups in the migration
code.
- The 4 patch series "mm/page_owner: add per-fd filter infrastructure
for print_mode and NUMA filtering" from Zhen Ni provides per-fd
filtering to page_owner in order to reduce the sometimes vast amount of
output it can produce.
- The 19 patch series "mm: Refactor bootmem gigantic hugepage
allocation" from Muchun Song is a "set of fixes and preparatory cleanups
around bootmem HugeTLB handling, sparse initialization ordering, and
related vmemmap setup".
- The 4 patch series "mm/zsmalloc: reduce lock contention in zs_free()"
from Wenchao Hao reduces lock contention in zs_free(), which dominates
the unmap path under memory pressure on Android (LMK kills) and on x86
servers running zswap-heavy workloads. Up to 1.83x improvement in
microbenchmarking.
- The 2 patch series "move alloc_tag.c file under mm/" from Suren
Baghdasaryan does that.
- The 6 patch series "samples/damon: handle damon_{start,stop}()
failures" from SJ Park fixes improper handling of damon_start(),
damon_stop(), and damon_call() failures across DAMON sample modules to
prevent potential memory leaks, operation disruptions and use-after-free
bugs.
- The 11 patch series "mm/damon/sysfs: kobject_del() directories that
users can create/remove" from SJ Park resolves an issue where delayed
sysfs directory removal under CONFIG_DEBUG_KOBJECT_RELEASE causes
creation failures due to duplicate directory names by adding missing
kobject_del() calls before creating new directories.
- The 3 patch series "mm: cleanup clear_not_present_full_ptes()" from
David Hildenbrand cleans up the core pte handling code.
- The 3 patch series "selftests/damon: misc fixes for test bugs" from
Kunwu Chan fixes several bugs in the DAMON selftests.
- The 2 patch series "selftests/damon: fix memcg_path staging handling"
from Cheng Nie fixes a bug in _damon_sysfs.py for damos_filter
memcg_path setup, and adds a test case for it in sysfs.py.
- The 2 patch series "selftests/damon: test kdamond refresh_ms" from
Ruslan Valiyev introduces selftest coverage for DAMON's refresh_ms sysfs
feature by updating the test control module and verifying that scheme
stats update automatically without manual intervention.
- The 5 patch series "mm/damon: five misc fixups" from Akinobu Mita
contains miscellaneous DAMON fixups.
- The 2 patch series "mm/damon/core: detect internal variation above
max_nr_regions/2" from Jiayuan Chen fixes DAMON's region splitting
behavior when region counts exceed half the maximum budget by
dynamically scaling down the split fraction as the limit approaches,
preventing large regions from staying un-split, and adds corresponding
KUnit test coverage.
- The 6 patch series "mm: preparatory patches for PMD level swap
entries" from Usama Arif refactors and cleans up PMD softleaf helpers,
call sites, and architecture flags to lay the groundwork for a follow-up
series that introduces PMD page table swap entries.
- The 11 patch series "mm/damon: update, optimize, and clean up doc,
tests, and code" from SJ Park updates DAMON design and ABI
documentation, expands unit and selftest coverage, optimizes
damon_commit_target_regions(), and cleans up recently added sysfs
interface code for better readability.
- The 2 patch series "mm/vmpressure: reduce CPU, memory and code
overhead on cgroup v2" from Usama Arif optimizes vmpressure() by
skipping unnecessary work on cgroup v2 for userspace event notifications
and refactors v1-only eventfd handling into mm/memcontrol-v1.c to reduce
memory overhead and code complexity.
- The 10 patch series "selftests/mm: refactor pkey helpers and fix mmap
error handling" from Hongfu Li refactors pkeys shared tracing and
assertion helpers into a common file, unifies protection key selftests
to use consistent diagnostic logging and assertions, and enforces
standardized MAP_FAILED return checks for mmap() calls across the tests.
- The 18 patch series "mm/damon: optimize out nr_accesses_bp" from SJ
Park replaces the error-prone, continuously updated nr_accesses_bp field
in damon_region with an on-demand moving sum function
(damon_nr_accesses_mvsum()), reducing structure memory overhead and
avoiding state corruption bugs.
- The 6 patch series "Open HugeTLB allocation routine for more generic
use" from Ackerley Tng decouples HugeTLB folio allocation from VMA
dependencies by introducing hugetlb_alloc_folio(), enabling subsystems
like guest_memfd to allocate HugeTLB folios without standard VMA
reservations or pseudo-VMAs.
- The 3 patch series "mm/damon: provide pseudo moving sum probe_hits"
from SJ Park integrates DAMON's probe_hits attribute counter into the
pseudo moving sum infrastructure, enabling real-time, online monitoring
without waiting for full aggregation intervals.
- The 18 patch series "mm: Some cleanups for page allocator APIs" from
Brendan Jackman simplifies and refactors the page allocator entry points
and flags by unifying allocation paths, adding internal alloc_flags
arguments, and eliminating redundant __ prefixed alloc_pages variants.
- The 5 patch series "Fix incorrect access of hugetlb pte entries" from
Dev Jain enforces the consistent use of huge_ptep_get() instead of
ptep_get() for HugeTLB entries and fixes an unaligned address issue in
arm64's huge_ptep_get() implementation.
- The 8 patch series "mm/damon: validate all parameters in the core"
from SJ Park consolidates parameter validation into the DAMON core
specifically within damon_start() and damon_commit_ctx() to centralize
error checking, eliminate caller-side redundant checks and to improve
maintenance efficiency.
- The 3 patch series "tools/mm/page_owner_sort: fix filtering and
cleanup issues" from Yichong Chen renames is_need() to filter_record()
for clearer return semantics, fixes per-record allocation memory leaks
and bounds output copies in search_pattern() to address an existing
buffer issue.
- The 4 patch series "memcg: bail out reclaim when memcg is dying" from
Jiayuan Chen mitigates a system-wide stall which occurs when a cgroup is
removed while one of its memory control files is doing synchronous
reclaim.
- The 5 patch series "mm/memory-failure: add panic option for
unrecoverable pages" from Breno Leitao introduces an opt-in
vm.panic_on_unrecoverable_memory_failure sysctl that immediately panics
the kernel on unrecoverable memory errors in kernel-owned pages to
preserve error context and prevent delayed, silent data corruption.
- The 11 patch series "mm/damon: refactor damon_{start,stop,commit}()
for simple error handling" from SJ Park refactors the DAMON core API
functions to guarantee that all contexts are fully stopped when
damon_start(), damon_stop(), or damon_commit() fail, eliminating the
need for complex and error-prone caller-side cleanup code.
- The 5 patch series "Keep tail page private zero at free and folio
split" from Zi Yan adds checks to ensure tail_page->private is zero when
freeing compound or high-order pages and when promoting tail pages
during large folio splits. By validating these fields at free and split
time, it allows the removal of redundant private field clearing inside
prep_compound_tail().
- The 4 patch series "mm: drop redundant lru_add_drain in anon folio
reuse paths" from Barry Song eliminates redundant lru_add_drain() calls
in wp_can_reuse_anon_folio() and do_swap_page() to reduce LRU lock
contention and system overhead.
By validating folio refcounts against the LRU cache before draining
and removing unnecessary drains in the swap path, it achieves up to a
30.5% reduction in drain calls during heavy swap workloads.
- The 3 patch series "mm: clean up folio LRU and swap declarations" from
Jianyue Wu reorganizes folio LRU and swap code by relocating
page-cluster state to mm/swap_state.c, renaming mm/swap.c to mm/folio.c,
and moving MM-internal reclaim declarations into mm/internal.h.
- The 15 patch series "userfaultfd: working set tracking for VM guest
memory" from Kiryl Shutsemau 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.
- The 10 patch series "mm: remove CONFIG_HAVE_BOOTMEM_INFO_NODE (Part
2)" from David Hildenbrand removes the remaining pieces of
CONFIG_HAVE_BOOTMEM_INFO_NODE, performing some smaller cleanups around
freeing of reserved vmemmap pages on the way.
- The 7 patch series "mm/damon: update probe hits for runtime parameter
commits" from SJ Park ensures that DAMON's probe_hits attribute counter
is properly updated when monitoring intervals are changed at runtime,
matching the behavior of nr_accesses. To achieve this, it refactors and
renames existing helper functions for shared use, applies the updates to
probe_hits, and handles edge cases in damon_probe_hits_mvsum() to
maintain measurement accuracy.
- The 3 patch series "KSM: performance optimizations for rmap_walk_ksm"
from xu xin resolves a severe KSM reverse-mapping performance bottleneck
where thousands of split VMAs sharing a single anon_vma cause extended
lock contention. By adding an interval-filtering check during the rmap
walk, it reduces worst-case anon_vma lock hold times from over 500ms
down to under 2ms, preventing application freezes and latency spikes
under memory pressure.
- The 3 patch series "mm: split a couple of headers from internal.h"
from Mike Rapoport splits declarations related to mm_init, memblock,
vmalloc and sparse into new headers.
- The 2 patch series "KSM: use linear_page_index in collect_procs_ksm()"
from xu xin applies the interval tree optimization from rmap_walk_ksm()
to collect_procs_ksm() to avoid iterating over non-matching VMAs during
KSM memory error handling. It hoists loop-invariant address
initialization and restricts the anon_vma_interval_tree_foreach walk to
a targeted page offset range, reducing redundant checks and improving
lookup efficiency.
- The 3 patch series "selftests/mm: avoid false failures in hugetlb and
KSM tests" from Sayali Patil fixes issues in the hugetlb and KSM MM
selftest categories that can report failures when the prerequisites for
the tests are not satisfied.
- The 19 patch series "mm/damon: introduce data attributes only
monitoring" from SJ Park introduces attribute-weighted region management
in DAMON, allowing users to prioritize specific data attributes (such as
page sizes or cgroups) over or instead of access monitoring.
By assigning weights to attribute probes, DAMON can completely disable
access tracking and adjust monitoring regions based on weighted
probe-hit counters to optimize monitoring quality for attribute-focused
workloads.
- The 8 patch series "mm/hmm: Add mmap lock-drop support for
userfaultfd-backed mappings" from Stanislav Kinsburskii extends
hmm_range_fault() to support userfaultfd-backed regions by allowing the
mmap lock to be dropped during fault handling via a new
hmm_range_fault_locked() helper.
By accepting a locked pointer and signaling retry status when lock
release occurs, it enables page fault resolution in userfaultfd regions
while preserving backward compatibility for existing callers.
- The 33 patch series "mm: make VMA page offset handling more
consistent" from Lorenzo Stoakes cleans up and standardizes how
vma->vm_pgoff is accessed and manipulated across file-backed and
anonymous mappings in the kernel.
It introduces dedicated helper functions such as vma_start_pgoff(),
vma_end_pgoff(), vma_set_pgoff() and linear_page_delta() while renaming
rmap interval tree helpers to better reflect their functionality.
These changes establish a cleaner foundation for future work that will
unify virtual page offset indexing for all anonymous and CoW'd folios.
- The 3 patch series "mm: handle device-private PMDs in walk callbacks"
from Usama Arif addresses kernel panics and state corruption caused by
MM walk callbacks reaching non-present device-private PMD swap entries
created during HMM migrations.
It ensures that functions which acquire pmd_trans_huge_lock() properly
recognize device-private PMDs instead of assuming a present THP or a
standard migration entry.
- The 5 patch series "mm/rmap: Refactor try_to_unmap_one" from Dev Jain
refactors try_to_unmap_one by modularizing Hugetlb, anonymous-lazyfree,
and anonymous-swapbacked logic into dedicated functions, laying the
structural groundwork for batched anonymous large folio unmapping.
- The 4 patch series "Docs/ABI/damon: sysfs ABI document fixes and
additions" from Song Hu fixes typos and fills in missing entries in the
DAMON sysfs ABI document.
- The 10 patch series "dax/kmem: atomic whole-device hotplug via sysfs"
from Gregory Price introduces an atomic sysfs state attribute and
supporting DAX/MM infrastructure to prevent userland races when
offlining and removing entire memory regions.
By adding an unplugged state alongside standard online modes, it
enables whole-device atomic hotplug control while preserving backward
compatibility.
- The 13 patch series "mm: convert more vm_flags_t users to vma_flags_t"
from Lorenzo Stoakes continues transitioning the kernel from the
deprecated vm_flags_t type to vma_flags_t across core memory management
infrastructure.
It replaces legacy type usage in core functions such as do_mmap(),
unmapped area allocation, mm->def_vma_flags, and VMA operations like
mlock, mprotect, and mremap.
- The 2 patch series "Two small patches to clean up mm/mm_slot.h" from
xu xin refactors mm_slot.h by introducing mm_slot_remove() to unify
duplicate slot deletion sequences in khugepaged and KSM. It also adds
code documentation explaining why mm_slot_lookup and mm_slot_insert must
remain as preprocessor macros rather than static inline functions.
- The 10 patch series "mm/damon/core: hide core-private struct fields"
from SJ Park cleans up DAMON core structures by consistently marking
internal-only fields with private: comment tags to prevent improper
direct access from outer layers.
It enforces encapsulation across core structures including
damon_region, damon_target, and damon_ctx and updates DAMON_SYSFS to
interact through approved access APIs instead of exposing raw struct
members.
- The 6 patch series "mm/damon: unurgent fixes for infinite loop, NULL
de-ref and races" from SJ Park addresses potential infinite loops, NULL
dereferences, and race conditions identified in DAMON.
It fixes an infinite loop triggered by extreme user configurations, a
NULL pointer dereference within unit tests and minor monitoring
accuracy degradation caused by subtle runtime races.
- The 2 patch series "mm/page_alloc: fixes for free_pages_nolock() on
RT/UP" from Brendan Jackman fixes an NMI safety flaw in
__free_frozen_pages() where freeing pages on non-SMP or PREEMPT_RT
kernels can bypass can_spin_trylock() checks via non-PCP or isolated
migration paths.
It also resolves potential kernel crashes and privilege escalation
risks triggered when BPF tracing runs in NMI context alongside memory
hotplug or large allocation frees.
- The 4 patch series "mm/page_alloc: couple of followups for recent
cleanups" from Brendan Jackman cleans up and updates page allocator
nomenclature, documentation, and debug assertions.
It aligns internal FPI_ flags with the public "nolock" naming
convention, removes outdated internal implementation details from
high-level page allocator comments, and eliminates obsolete VM_BUG_ON()
assertions in allocation paths.
- The 3 patch series "mm/mseal: further cleanups" from Lorenzo Stoakes
refactors and simplifies the mseal implementation by clarifying API
boundaries and removing unnecessary code complexity.
It replaces generic do_mseal() usage outside the syscall with a
dedicated mseal_mmap_page_zero() helper for MMAP_PAGE_ZERO, eliminates
mm_struct parameters to enforce that sealing applies only to
current->mm, and streamlines overall logic and comments with no
functional changes intended.
- The 4 patch series "mm/vmscan: fix swappiness=max and clean up
per-node proactive reclaim" from Ridong Chen resolves reclaim behavior
bugs and cleans up function parameters across memory reclaim paths.
It fixes swappiness=max in both standard reclaim and MGLRU so
unswappable anonymous memory no longer falls back to evicting page
cache, ensures reclaim_store() returns accurate error codes instead of
collapsing all failures into -EAGAIN, and removes the obsolete gfp_mask
parameter from __node_reclaim().
- The 6 patch series "mm: mincore: misc cleanups" from Kefeng Wang
cleans up and simplifies the mincore code. Most importantly, it removes
the historical special behavior that always reports VM_PFNMAP pages as
non-resident.
- The 2 patch series "mm/huge_memory: drop dead split helper variants"
from Kiryl Shutsemau implements two trivial cleanups in the folio split
API.
- The 7 patch series "mm/damon: fix uninitialized DAMOS field and kunit
exec expectation bugs" from SJ Park resolves minor operational and
testing bugs in DAMON identified by Sashiko. It initializes the
damos->last_applied field to prevent occasional efficiency degradation
and fixes invalid memory accesses in DAMON KUnit tests during test
failure handling.
- The 3 patch series "cleanup for stable_page_flags()" from Jinjiang Tu
cleans up and refactors stable_page_flags() used by /proc/kpageflags
without altering functionality.
It uses BIT_ULL() to prevent shift-overflow warnings on 64-bit flag
bits, converts folio-specific flag checks to standard folio_test_*()
helpers, and removes redundant CONFIG_PAGE_IDLE_FLAG handling.
- The 3 patch series "Batch unmap of uffd-wp file folios" from Dev Jain
extends batched folio unmapping support to file folios within
userfaultfd write-protect (uffd-wp) VMAs by adding batching capabilities
to pte_install_uffd_wp_if_needed().
This removes special-case restrictions on uffd-wp VMAs in
try_to_unmap_one(), significantly simplifying the function's control
flow and complexity.
- The 3 patch series "mm/early_ioremap: clarify and clean up
early_ioremap_reset()" from Sang-Heon Jeon clarifies and cleans up the
architecture-specific usage of __late_set_fixmap() and
__late_clear_fixmap() after early_ioremap_reset().
It adds explicit documentation regarding when early_ioremap_reset()
must be called and removes redundant macro definitions and reset calls
in the RISC-V and ARM64 architectures.
- The 4 patch series "mm: fix reclaim storms in defrag_mode" from
Johannes Weiner addresses severe performance regressions, swap storms,
and spurious OOMs caused by vm.defrag_mode=1 under high memory pressure
in Meta production.
It updates the page allocator slowpath so non-movable allocation
requests actively trigger direct reclaim and direct compaction at
pageblock_order scale, allowing them to claim whole pageblocks rather
than spinning unproductively.
- The 2 patch series "zram: lockmap tweaks" from Sebastian Siewior
optimizes and fixes lockdep tracking for zram devices by consolidating
per-entry lockmaps and isolating lock classes across multiple instances.
It reduces memory overhead by replacing per-entry lockdep_map instances
with a single map per struct zram, and assigns a dynamic lock_class_key
to each instance to prevent false deadlock reports when different zram
devices are backed by distinct filesystems.
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Merge tag 'mm-stable-2026-08-18-18-39' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- "mm: drop "sub" prefix from various places" (Dev Jain)
page->folio conversion and a naming cleanup
- "mm/kasan: remove redundant initialization for kasan_flag_write_only"
(Igor Putko)
KASAN cleanup work
- "mm/filemap: reduce unnecessary xarray lookups" (Chi Zhiling)
Small speedup in the pagecaache read code
- "mm/percpu: Fix possible NOFS/NOIO reclaim recursion" (Kaitao Cheng)
Improve the vmalloc code - mainly the avoidance of GFP_KERNEL
allocations when the caller asked for GFP_NOFS or GFP_NOIO
- "mm/kmemleak: avoid soft lockup when scanning task stacks" (Breno
Leitao)
Avoid a soft lockup watchdog trigger from the kmemleak scanning code
in extreme situations
- "mm/page_owner: misc cleanups" (Ye Liu)
Cleanups to the page_owner code. For some reason lots of people have
been working on the page_owner code this cycle.
- "mm: convert to walk_page_range_vma() to eliminate find_vma()"
(Kefeng Wang)
Simplify and accelerate the page walking library function
- "mm/migrate: preparatory cleanups for batch copy and offload"
(Shivank Garg)
Cleanups in the migration code
- "mm/page_owner: add per-fd filter infrastructure for print_mode and
NUMA filtering" (Zhen Ni)
Per-fd filtering to page_owner in order to reduce the sometimes vast
amount of output it can produce
- "mm: Refactor bootmem gigantic hugepage allocation" (Muchun Song)
Fixes and preparatory cleanups around bootmem HugeTLB handling,
sparse initialization ordering, and related vmemmap setup
- "mm/zsmalloc: reduce lock contention in zs_free()" (Wenchao Hao)
Reduce lock contention in zs_free(), which dominates the unmap path
under memory pressure on Android (LMK kills) and on x86 servers
running zswap-heavy workloads.
Up to 1.83x improvement in microbenchmarking.
- "move alloc_tag.c file under mm/" (Suren Baghdasaryan)
- "samples/damon: handle damon_{start,stop}() failures" (SJ Park)
Fix improper handling of damon_start(), damon_stop(), and
damon_call() failures across DAMON sample modules to prevent
potential memory leaks, operation disruptions and use-after-free
bugs
- "mm/damon/sysfs: kobject_del() directories that users can
create/remove" (SJ Park)
Fix delayed sysfs directory removal under DEBUG_KOBJECT_RELEASE
causeing creation failures due to duplicate directory names by adding
missing kobject_del() calls before creating new directories
- "mm: cleanup clear_not_present_full_ptes()" (David Hildenbrand)
Clean up the core pte handling code
- "selftests/damon: misc fixes for test bugs" (Kunwu Chan)
Fix several bugs in the DAMON selftests
- "selftests/damon: fix memcg_path staging handling" (Cheng Nie)
Fix a bug in _damon_sysfs.py for damos_filter memcg_path setup, and
add a test case for it in sysfs.py.
- "selftests/damon: test kdamond refresh_ms" (Ruslan Valiyev)
Selftest coverage for DAMON's refresh_ms sysfs feature by updating
the test control module and verifying that scheme stats update
automatically without manual intervention
- "mm/damon: five misc fixups" (Akinobu Mita)
Miscellaneous DAMON fixups.
- "mm/damon/core: detect internal variation above max_nr_regions/2"
(Jiayuan Chen)
Fix DAMON's region splitting behavior when region counts exceed half
the maximum budget by dynamically scaling down the split fraction as
the limit approaches, preventing large regions from staying un-split,
and add corresponding KUnit test coverage
- "mm: preparatory patches for PMD level swap entries" (Usama Arif)
Refactor and clean up PMD softleaf helpers, call sites, and
architecture flags to lay the groundwork for a follow-up series that
introduces PMD page table swap entries
- "mm/damon: update, optimize, and clean up doc, tests, and code" (SJ
Park)
Update DAMON design and ABI documentation, expands unit and selftest
coverage, optimize damon_commit_target_regions(), and clean up
recently added sysfs interface code for better readability
- "mm/vmpressure: reduce CPU, memory and code overhead on cgroup v2"
(Usama Arif)
Optimize vmpressure() by skipping unnecessary work on cgroup v2 for
userspace event notifications and refactor v1-only eventfd handling
into mm/memcontrol-v1.c to reduce memory overhead and code complexity
- "selftests/mm: refactor pkey helpers and fix mmap error handling"
(Hongfu Li)
Refactor pkeys shared tracing and assertion helpers into a common
file, unify protection key selftests to use consistent diagnostic
logging and assertions, and enforce standardized MAP_FAILED return
checks for mmap() calls across the tests
- "mm/damon: optimize out nr_accesses_bp" (SJ Park)
Replace the error-prone, continuously updated nr_accesses_bp field in
damon_region with an on-demand moving sum function, reducing
structure memory overhead and avoiding state corruption bugs
- "Open HugeTLB allocation routine for more generic use" (Ackerley Tng)
Decouple HugeTLB folio allocation from VMA dependencies by
introducing hugetlb_alloc_folio(), enabling subsystems like
guest_memfd to allocate HugeTLB folios without standard VMA
reservations or pseudo-VMAs
- "mm/damon: provide pseudo moving sum probe_hits" (SJ Park)
Integrate DAMON's probe_hits attribute counter into the pseudo moving
sum infrastructure, enabling real-time, online monitoring without
waiting for full aggregation intervals
- "mm: Some cleanups for page allocator APIs" (Brendan Jackman)
Simplify and refactor the page allocator entry points and flags by
unifying allocation paths, adding internal alloc_flags arguments, and
eliminating redundant __ prefixed alloc_pages variants.
- "Fix incorrect access of hugetlb pte entries" (Dev Jain)
Enforce the consistent use of huge_ptep_get() instead of ptep_get()
for HugeTLB entries and fixes an unaligned address issue in arm64's
huge_ptep_get() implementation
- "mm/damon: validate all parameters in the core" (SJ Park)
Consolidate parameter validation into the DAMON core specifically
within damon_start() and damon_commit_ctx() to centralize error
checking, eliminate caller-side redundant checks and to improve
maintenance efficiency
- "tools/mm/page_owner_sort: fix filtering and cleanup issues" (Yichong
Chen)
Rename is_need() to filter_record() for clearer return semantics, fix
per-record allocation memory leaks and bound output copies in
search_pattern() to address an existing buffer issue
- "memcg: bail out reclaim when memcg is dying" (Jiayuan Chen)
Mitigate a system-wide stall which occurs when a cgroup is removed
while one of its memory control files is doing synchronous reclaim
- "mm/memory-failure: add panic option for unrecoverable pages" (Breno
Leitao)
Introduce an opt-in vm.panic_on_unrecoverable_memory_failure sysctl
that immediately panics the kernel on unrecoverable memory errors in
kernel-owned pages to preserve error context and prevent delayed,
silent data corruption
- "mm/damon: refactor damon_{start,stop,commit}() for simple error
handling" (SJ Park)
Refactor the DAMON core API functions to guarantee that all contexts
are fully stopped when damon_start(), damon_stop(), or damon_commit()
fail, eliminating the need for complex and error-prone caller-side
cleanup code
- "Keep tail page private zero at free and folio split" (Zi Yan)
Add checks to ensure tail_page->private is zero when freeing compound
or high-order pages and when promoting tail pages during large folio
splits. By validating these fields at free and split time, it allows
the removal of redundant private field clearing inside
prep_compound_tail()
- "mm: drop redundant lru_add_drain in anon folio reuse paths" (Barry
Song)
Eliminate redundant lru_add_drain() calls in
wp_can_reuse_anon_folio() and do_swap_page() to reduce LRU lock
contention and system overhead
By validating folio refcounts against the LRU cache before draining
and removing unnecessary drains in the swap path, it achieves up to a
30.5% reduction in drain calls during heavy swap workloads
- "mm: clean up folio LRU and swap declarations" (Jianyue Wu)
Reorganize folio LRU and swap code by relocating page-cluster state
to mm/swap_state.c, renaming mm/swap.c to mm/folio.c, and moving
MM-internal reclaim declarations into mm/internal.h.
- "userfaultfd: working set tracking for VM guest memory" (Kiryl
Shutsemau)
Add 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
- "mm: remove CONFIG_HAVE_BOOTMEM_INFO_NODE (Part 2)" (David
Hildenbrand)
Remove the remaining pieces of CONFIG_HAVE_BOOTMEM_INFO_NODE,
performing some smaller cleanups around freeing of reserved vmemmap
pages on the way.
- "mm/damon: update probe hits for runtime parameter commits" (SJ Park)
Ensure that DAMON's probe_hits attribute counter is properly updated
when monitoring intervals are changed at runtime, matching the
behavior of nr_accesses. To achieve this, it refactors and renames
existing helper functions for shared use, applies the updates to
probe_hits, and handles edge cases in damon_probe_hits_mvsum() to
maintain measurement accuracy.
- "KSM: performance optimizations for rmap_walk_ksm" (xu xin)
Resolve a severe KSM reverse-mapping performance bottleneck where
thousands of split VMAs sharing a single anon_vma cause extended lock
contention.
By adding an interval-filtering check during the rmap walk, it
reduces worst-case anon_vma lock hold times from over 500ms down to
under 2ms, preventing application freezes and latency spikes under
memory pressure.
- "mm: split a couple of headers from internal.h" (Mike Rapoport)
Split declarations related to mm_init, memblock, vmalloc and sparse
into new headers
- "KSM: use linear_page_index in collect_procs_ksm()" (xu xin)
Apply the interval tree optimization from rmap_walk_ksm() to
collect_procs_ksm() to avoid iterating over non-matching VMAs during
KSM memory error handling.
It hoists loop-invariant address initialization and restricts the
anon_vma_interval_tree_foreach walk to a targeted page offset range,
reducing redundant checks and improving lookup efficiency.
- "selftests/mm: avoid false failures in hugetlb and KSM tests" (Sayali
Patil)
Fix issues in the hugetlb and KSM MM selftest categories that can
report failures when the prerequisites for the tests are not
satisfied
- "mm/damon: introduce data attributes only monitoring" (SJ Park)
Introduce attribute-weighted region management in DAMON, allowing
users to prioritize specific data attributes (such as page sizes or
cgroups) over or instead of access monitoring.
By assigning weights to attribute probes, DAMON can completely
disable access tracking and adjust monitoring regions based on
weighted probe-hit counters to optimize monitoring quality for
attribute-focused workloads.
- "mm/hmm: Add mmap lock-drop support for userfaultfd-backed mappings"
(Stanislav Kinsburskii)
Extend hmm_range_fault() to support userfaultfd-backed regions by
allowing the mmap lock to be dropped during fault handling via a new
hmm_range_fault_locked() helper.
By accepting a locked pointer and signaling retry status when lock
release occurs, it enables page fault resolution in userfaultfd
regions while preserving backward compatibility for existing callers.
- "mm: make VMA page offset handling more consistent" (Lorenzo Stoakes)
Clean up and standardize how vma->vm_pgoff is accessed and
manipulated across file-backed and anonymous mappings in the kernel
It introduces dedicated helper functions such as vma_start_pgoff(),
vma_end_pgoff(), vma_set_pgoff() and linear_page_delta() while
renaming rmap interval tree helpers to better reflect their
functionality.
These changes establish a cleaner foundation for future work that
will unify virtual page offset indexing for all anonymous and CoW'd
folios.
- "mm: handle device-private PMDs in walk callbacks" (Usama Arif)
Address kernel panics and state corruption caused by MM walk
callbacks reaching non-present device-private PMD swap entries
created during HMM migrations
It ensures that functions which acquire pmd_trans_huge_lock()
properly recognize device-private PMDs instead of assuming a present
THP or a standard migration entry.
- "mm/rmap: Refactor try_to_unmap_one" (Dev Jain)
Refactor try_to_unmap_one by modularizing Hugetlb,
anonymous-lazyfree, and anonymous-swapbacked logic into dedicated
functions, laying the structural groundwork for batched anonymous
large folio unmapping.
- "Docs/ABI/damon: sysfs ABI document fixes and additions" (Song Hu)
Fix typos and fills in missing entries in the DAMON sysfs ABI
document
- "dax/kmem: atomic whole-device hotplug via sysfs" (Gregory Price)
Introduce an atomic sysfs state attribute and supporting DAX/MM
infrastructure to prevent userland races when offlining and removing
entire memory regions
By adding an unplugged state alongside standard online modes, it
enables whole-device atomic hotplug control while preserving backward
compatibility.
- "mm: convert more vm_flags_t users to vma_flags_t" (Lorenzo Stoakes)
Continue transitioning the kernel from the deprecated vm_flags_t type
to vma_flags_t across core memory management infrastructure.
It replaces legacy type usage in core functions such as do_mmap(),
unmapped area allocation, mm->def_vma_flags, and VMA operations like
mlock, mprotect, and mremap.
- "Two small patches to clean up mm/mm_slot.h" (xu xin)
Refactor mm_slot.h by introducing mm_slot_remove() to unify duplicate
slot deletion sequences in khugepaged and KSM. It also adds code
documentation explaining why mm_slot_lookup and mm_slot_insert must
remain as preprocessor macros rather than static inline functions.
- "mm/damon/core: hide core-private struct fields" (SJ Park)
Clean up DAMON core structures by consistently marking internal-only
fields with private: comment tags to prevent improper direct access
from outer layers.
It enforces encapsulation across core structures including
damon_region, damon_target, and damon_ctx and updates DAMON_SYSFS to
interact through approved access APIs instead of exposing raw struct
members.
- "mm/damon: unurgent fixes for infinite loop, NULL de-ref and races"
(SJ Park)
Address potential infinite loops, NULL dereferences, and race
conditions identified in DAMON
It fixes an infinite loop triggered by extreme user configurations, a
NULL pointer dereference within unit tests and minor monitoring
accuracy degradation caused by subtle runtime races.
- "mm/page_alloc: fixes for free_pages_nolock() on RT/UP" (Brendan
Jackman)
Fix an NMI safety flaw in __free_frozen_pages() where freeing pages
on non-SMP or PREEMPT_RT kernels can bypass can_spin_trylock() checks
via non-PCP or isolated migration paths.
It also resolves potential kernel crashes and privilege escalation
risks triggered when BPF tracing runs in NMI context alongside memory
hotplug or large allocation frees.
- "mm/page_alloc: couple of followups for recent cleanups" (Brendan
Jackman)
Clean up and update page allocator nomenclature, documentation, and
debug assertions.
It aligns internal FPI_ flags with the public "nolock" naming
convention, removes outdated internal implementation details from
high-level page allocator comments, and eliminates obsolete
VM_BUG_ON() assertions in allocation paths.
- "mm/mseal: further cleanups" (Lorenzo Stoakes)
Refactor and simplify the mseal implementation by clarifying API
boundaries and removing unnecessary code complexity.
It replaces generic do_mseal() usage outside the syscall with a
dedicated mseal_mmap_page_zero() helper for MMAP_PAGE_ZERO,
eliminates mm_struct parameters to enforce that sealing applies only
to current->mm, and streamlines overall logic and comments with no
functional changes intended.
- "mm/vmscan: fix swappiness=max and clean up per-node proactive
reclaim" (Ridong Chen)
Resolve reclaim behavior bugs and clean up function parameters across
memory reclaim paths
It fixes swappiness=max in both standard reclaim and MGLRU so
unswappable anonymous memory no longer falls back to evicting page
cache, ensures reclaim_store() returns accurate error codes instead
of collapsing all failures into -EAGAIN, and removes the obsolete
gfp_mask parameter from __node_reclaim().
- "mm: mincore: misc cleanups" (Kefeng Wang)
Clean up and simplifies the mincore code. Most importantly, it
removes the historical special behavior that always reports VM_PFNMAP
pages as non-resident.
- "mm/huge_memory: drop dead split helper variants" (Kiryl Shutsemau)
Two trivial cleanups in the folio split API
- "mm/damon: fix uninitialized DAMOS field and kunit exec expectation
bugs" (SJ Park)
Resolve minor operational and testing bugs in DAMON identified by
Sashiko. It initializes the damos->last_applied field to prevent
occasional efficiency degradation and fixes invalid memory accesses
in DAMON KUnit tests during test failure handling.
- "cleanup for stable_page_flags()" (Jinjiang Tu)
Clean up and refactor stable_page_flags() used by /proc/kpageflags
without altering functionality.
It uses BIT_ULL() to prevent shift-overflow warnings on 64-bit flag
bits, converts folio-specific flag checks to standard folio_test_*()
helpers, and removes redundant CONFIG_PAGE_IDLE_FLAG handling.
- "Batch unmap of uffd-wp file folios" (Dev Jain)
Extend batched folio unmapping support to file folios within
userfaultfd write-protect (uffd-wp) VMAs by adding batching
capabilities to pte_install_uffd_wp_if_needed().
This removes special-case restrictions on uffd-wp VMAs in
try_to_unmap_one(), significantly simplifying the function's control
flow and complexity.
- "mm/early_ioremap: clarify and clean up early_ioremap_reset()"
(Sang-Heon Jeon)
Clarify and clean up the architecture-specific usage of
__late_set_fixmap() and __late_clear_fixmap() after
early_ioremap_reset()
It adds explicit documentation regarding when early_ioremap_reset()
must be called and removes redundant macro definitions and reset
calls in the RISC-V and ARM64 architectures.
- "mm: fix reclaim storms in defrag_mode" (Johannes Weiner)
Address severe performance regressions, swap storms, and spurious
OOMs caused by vm.defrag_mode=1 under high memory pressure in Meta
production
It updates the page allocator slowpath so non-movable allocation
requests actively trigger direct reclaim and direct compaction at
pageblock_order scale, allowing them to claim whole pageblocks rather
than spinning unproductively.
- "zram: lockmap tweaks" (Sebastian Siewior)
Optimize and fix lockdep tracking for zram devices by consolidating
per-entry lockmaps and isolate lock classes across multiple instances
This reduces memory overhead by replacing per-entry lockdep_map
instances with a single map per struct zram, and assigns a dynamic
lock_class_key to each instance to prevent false deadlock reports
when different zram devices are backed by distinct filesystems.
* tag 'mm-stable-2026-08-18-18-39' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (501 commits)
selftests/mm: thuge-gen: fix test_shmget() for PAGE_SIZE check
selftests/mm: unpoison pages in memory-failure teardown
mm/shmem: downgrade final i_blocks check in shmem_evict_inode() to pr_warn()
mm/khugepaged: replace mutex_lock/mutex_unlock usage with guard macro
mm/zsmalloc: fix release order of locks in zs_page_migrate()
Documentation: zram: remove sections numbering
ksm: stop iterating VMAs when ksm_test_exit returns true
mm: fold userfaultfd_rwp() to false without CONFIG_ARCH_HAS_PTE_PROTNONE
mm/migrate: report RCU-tasks quiescent states in migrate_pages_batch()
zram: use a custom key for each zram object
zram: move lockmap to be per-zram instead per table
selftests/mm: fix gup_longterm EINVAL error message
mm: page_alloc: fix non-movable reclaim storm in defrag_mode
mm: page_alloc: move capture_control to the page allocator
mm: compaction: support non-movable compaction for pageblock requests
mm: page_alloc: __GFP_FS lockdep annotation for direct compaction
hugetlb: evaluate subpool free state while locked
mm/damon: remove trailing semicolons after function definitions
mm/damon/ops-common: prevent migration fallback to non-target nodes
mm/damon: update outdated comment about DAMOS filter handling
...
|
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Lorenzo Stoakes (ARM)
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4c1c2d2418 |
mm/mseal: limit scope of mseal address zero to address zero
Commit
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Christian Brauner
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2a4d517681 |
binfmt_elf: consume a stashed PT_INTERP substitute
When a binfmt_misc loader entry stashed bprm->loader use it instead of opening the path named in PT_INTERP. The substitution deliberately changes as little as possible. Ownership transfers into the local interpreter reference which the existing success and error paths already release. A binary without PT_INTERP has nothing to substitute for. Drop the override at the end of the segment scan and load the binary natively. Nothing sets bprm->loader yet. Link: https://patch.msgid.link/20260721-work-bpf-binfmt_misc-ptinterp-v2-16-e57866e4ae0f@kernel.org Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org> |
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Christian Brauner
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b0f09c0796 |
exec: add AT_FLAGS_TRANSPARENT_INTERP
A transparent binfmt_misc dispatch hands the binary to the interpreter
through AT_EXECFD and leaves the argument vector exactly as the caller
built it. The loader on the receiving end has to know which contract it
got.
On the classic 'O'/'C' entries the binary's path is spliced into the
argument vector and the loader consumes arguments. In transparent mode
nothing was spliced and argv belongs entirely to the program. This
cannot be inferred from AT_EXECFD alone. Raise a new AT_FLAGS bit
following the AT_FLAGS_PRESERVE_ARGV0 precedent added for qemu-user in
commit
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Lorenzo Stoakes (Oracle)
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5fb55e951c |
mm: unexport vm_brk_flags() and eliminate vm_flags parameter
This function is only used by elf_load(), and that is a static function that doesn't need an exported symbol to invoke an internal function, so un-EXPORT_SYMBOLS() it. Also, the vm_flags parameter is unnecessary, as we only ever set VM_EXEC, so simply make this parameter a boolean. While we're here, clean up the mm.h definitions for the various vm_xxx() helpers so we actually specify parameter names and elide the redundant extern's. Link: https://lkml.kernel.org/r/7bada48ddf3f9dbd3e6c4fc50ec2f4de97706f52.1774034900.git.ljs@kernel.org Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Alexandre Ghiti <alex@ghiti.fr> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> Cc: "Borislav Petkov (AMD)" <bp@alien8.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Christian Brauner <brauner@kernel.org> Cc: David Hildenbrand <david@kernel.org> Cc: Dinh Nguyen <dinguyen@kernel.org> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Huacai Chen <chenhuacai@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Johannes Berg <johannes@sipsolutions.net> Cc: Kees Cook <kees@kernel.org> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Madhavan Srinivasan <maddy@linux.ibm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Ondrej Mosnacek <omosnace@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Moore <paul@paul-moore.com> Cc: Pedro Falcato <pfalcato@suse.de> Cc: Richard Weinberger <richard@nod.at> Cc: Russell King <linux@armlinux.org.uk> Cc: Stephen Smalley <stephen.smalley.work@gmail.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vineet Gupta <vgupta@kernel.org> Cc: WANG Xuerui <kernel@xen0n.name> Cc: Will Deacon <will@kernel.org> Cc: xu xin <xu.xin16@zte.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Mathieu Desnoyers
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3b68df9781 |
rseq: slice ext: Ensure rseq feature size differs from original rseq size
Before rseq became extensible, its original size was 32 bytes even though the active rseq area was only 20 bytes. This had the following impact in terms of userspace ecosystem evolution: * The GNU libc between 2.35 and 2.39 expose a __rseq_size symbol set to 32, even though the size of the active rseq area is really 20. * The GNU libc 2.40 changes this __rseq_size to 20, thus making it express the active rseq area. * Starting from glibc 2.41, __rseq_size corresponds to the AT_RSEQ_FEATURE_SIZE from getauxval(3). This means that users of __rseq_size can always expect it to correspond to the active rseq area, except for the value 32, for which the active rseq area is 20 bytes. Exposing a 32 bytes feature size would make life needlessly painful for userspace. Therefore, add a reserved field at the end of the rseq area to bump the feature size to 33 bytes. This reserved field is expected to be replaced with whatever field will come next, expecting that this field will be larger than 1 byte. The effect of this change is to increase the size from 32 to 64 bytes before we actually have fields using that memory. Clarify the allocation size and alignment requirements in the struct rseq uapi comment. Change the value returned by getauxval(AT_RSEQ_ALIGN) to return the value of the active rseq area size rounded up to next power of 2, which guarantees that the rseq structure will always be aligned on the nearest power of two large enough to contain it, even as it grows. Change the alignment check in the rseq registration accordingly. This will minimize the amount of ABI corner-cases we need to document and require userspace to play games with. The rule stays simple when __rseq_size != 32: #define rseq_field_available(field) (__rseq_size >= offsetofend(struct rseq_abi, field)) Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/20260220200642.1317826-3-mathieu.desnoyers@efficios.com |
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Linus Torvalds
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32a92f8c89 |
Convert more 'alloc_obj' cases to default GFP_KERNEL arguments
This converts some of the visually simpler cases that have been split over multiple lines. I only did the ones that are easy to verify the resulting diff by having just that final GFP_KERNEL argument on the next line. Somebody should probably do a proper coccinelle script for this, but for me the trivial script actually resulted in an assertion failure in the middle of the script. I probably had made it a bit _too_ trivial. So after fighting that far a while I decided to just do some of the syntactically simpler cases with variations of the previous 'sed' scripts. The more syntactically complex multi-line cases would mostly really want whitespace cleanup anyway. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Linus Torvalds
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323bbfcf1e |
Convert 'alloc_flex' family to use the new default GFP_KERNEL argument
This is the exact same thing as the 'alloc_obj()' version, only much smaller because there are a lot fewer users of the *alloc_flex() interface. As with alloc_obj() version, this was done entirely with mindless brute force, using the same script, except using 'flex' in the pattern rather than 'objs*'. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Linus Torvalds
|
bf4afc53b7 |
Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
This was done entirely with mindless brute force, using
git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'
to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.
Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.
For the same reason the 'flex' versions will be done as a separate
conversion.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Kees Cook
|
69050f8d6d |
treewide: Replace kmalloc with kmalloc_obj for non-scalar types
This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook <kees@kernel.org> |
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Thomas Gleixner
|
0f085b4188 |
rseq: Provide and use rseq_set_ids()
Provide a new and straight forward implementation to set the IDs (CPU ID, Node ID and MM CID), which can be later inlined into the fast path. It does all operations in one scoped_user_rw_access() section and retrieves also the critical section member (rseq::cs_rseq) from user space to avoid another user..begin/end() pair. This is in preparation for optimizing the fast path to avoid extra work when not required. On rseq registration set the CPU ID fields to RSEQ_CPU_ID_UNINITIALIZED and node and MM CID to zero. That's the same as the kernel internal reset values. That makes the debug validation in the exit code work correctly on the first exit to user space. Use it to replace the whole related zoo in rseq.c Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Link: https://patch.msgid.link/20251027084307.393972266@linutronix.de |
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Svetlana Parfenova
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8c94db0ae9 |
binfmt_elf: preserve original ELF e_flags for core dumps
Some architectures, such as RISC-V, use the ELF e_flags field to encode
ABI-specific information (e.g., ISA extensions, fpu support). Debuggers
like GDB rely on these flags in core dumps to correctly interpret
optional register sets. If the flags are missing or incorrect, GDB may
warn and ignore valid data, for example:
warning: Unexpected size of section '.reg2/213' in core file.
This can prevent access to fpu or other architecture-specific registers
even when they were dumped.
Save the e_flags field during ELF binary loading (in load_elf_binary())
into the mm_struct, and later retrieve it during core dump generation
(in fill_note_info()). Kconfig option CONFIG_ARCH_HAS_ELF_CORE_EFLAGS
is introduced for architectures that require this behaviour.
Signed-off-by: Svetlana Parfenova <svetlana.parfenova@syntacore.com>
Link: https://lore.kernel.org/r/20250901135350.619485-1-svetlana.parfenova@syntacore.com
Signed-off-by: Kees Cook <kees@kernel.org>
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Xichao Zhao
|
a728ce8ffb |
binfmt_elf: Replace offsetof() with struct_size() in fill_note_info()
When dealing with structures containing flexible arrays, struct_size() provides additional compile-time checks compared to offsetof(). This enhances code robustness and reduces the risk of potential errors. Signed-off-by: Xichao Zhao <zhao.xichao@vivo.com> Link: https://lore.kernel.org/r/20250813115058.635742-1-zhao.xichao@vivo.com Signed-off-by: Kees Cook <kees@kernel.org> |
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Linus Torvalds
|
d900c4ce63 |
execve updates for v6.17
- Introduce regular REGSET note macros arch-wide (Dave Martin) - Remove arbitrary 4K limitation of program header size (Yin Fengwei) - Reorder function qualifiers for copy_clone_args_from_user() (Dishank Jogi) -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQRSPkdeREjth1dHnSE2KwveOeQkuwUCaIVKiAAKCRA2KwveOeQk u4zBAP4zUNj2+XyixVPXCzv+Hkle6zWs7yrzdA2yLxe8Qtwj5AD+N2I6MUGcCFGW W+uWxlWTtGLDqh1CplIUqTlxMi39Og4= =vYnE -----END PGP SIGNATURE----- Merge tag 'execve-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull execve updates from Kees Cook: - Introduce regular REGSET note macros arch-wide (Dave Martin) - Remove arbitrary 4K limitation of program header size (Yin Fengwei) - Reorder function qualifiers for copy_clone_args_from_user() (Dishank Jogi) * tag 'execve-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (25 commits) fork: reorder function qualifiers for copy_clone_args_from_user binfmt_elf: remove the 4k limitation of program header size binfmt_elf: Warn on missing or suspicious regset note names xtensa: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names um: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names x86/ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names sparc: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names sh: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names s390/ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names riscv: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names powerpc/ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names parisc: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names openrisc: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names nios2: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names MIPS: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names m68k: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names LoongArch: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names hexagon: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names csky: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names arm64: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names ... |
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Yin Fengwei
|
8030790477 |
binfmt_elf: remove the 4k limitation of program header size
We have assembly code generated by a script. GCC successfully compiles it. However, the kernel cannot load it on an ARM64 platform with a 4K page size. In contrast, the same ELF file loads correctly on the same platform with a 64K page size. The root cause is the Linux kernel's ELF_MIN_ALIGN limitation on the program headers of ELF files. The ELF file contains 78 program headers (the script inserts many holes when generating the assembly code). On ARM64 with a 4K page size, the ELF_MIN_ALLIGN enforces a maximum of 74 program headers, causing the ELF file to fail. However, with a 64K page size, the ELF_MIN_ALIGN is relaxed to over 1,184 program headers, allowing the file to run correctly. Cook kindly identified[1] that this limitation was introduced in Linux-0.99.15f without an explanation for its purpose. The ELF specification does not impose such a restriction on program headers. Removing the ELF_MIN_ALIGN limitation on program headers to align with the ELF spec. After removing ELF_MIN_ALIGN limitation, 64K size limitation still exist which should be sufficient. Suggested-by: Kees Cook <kees@kernel.org> Link: https://lore.kernel.org/linux-mm/202506270854.A729825@keescook/ [1] Signed-off-by: Yin Fengwei <fengwei_yin@linux.alibaba.com> Link: https://lore.kernel.org/r/20250717110108.55586-1-fengwei_yin@linux.alibaba.com Signed-off-by: Kees Cook <kees@kernel.org> |
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Dave Martin
|
a55128d392 |
binfmt_elf: Warn on missing or suspicious regset note names
Now that all regset definitions declare an explicit note name, warn if the note name is missing when generating a core dump. Simplify the fallback to always guess "LINUX", which is appropriate for all Linux-specific notes (i.e., all newly added notes, for a long time now). The one standard exception (PR_FPREG) will no longer have an "unexpected" note name overridden, but a warning will still be emitted. Also warn if the specified note name doesn't match the legacy pattern -- but don't bother to override the name in this case. This warning can be removed in future if new note types emerge that require a specific note name that is not "LINUX". No functional change, beyond the extra noise in dmesg and not overriding an unexpected note name for PR_FPREG any more. Now that all upstream arches are ported to use USER_REGSET_NOTE_TYPE(), new regsets created by copy-pasting existing code should end up correct by construction. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kees Cook <kees@kernel.org> Cc: Akihiko Odaki <akihiko.odaki@daynix.com> Reviewed-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp> Link: https://lore.kernel.org/r/20250701135616.29630-24-Dave.Martin@arm.com Signed-off-by: Kees Cook <kees@kernel.org> |
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Dave Martin
|
9674a1be4d |
binfmt_elf: Dump non-arch notes with strictly matching name and type
The note names for some arch-independent coredump notes are specified manually, albeit by referring to the NN_<foo> #define corresponding to the NT_<foo> #define that specifies the note type. Now that there are no exceptional cases, refactor fill_note() to pick the correct NN_ and NT_ macros implcitly for the requested note type. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kees Cook <kees@kernel.org> Cc: Akihiko Odaki <akihiko.odaki@daynix.com> Reviewed-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp> Link: https://lore.kernel.org/r/20250701135616.29630-4-Dave.Martin@arm.com Signed-off-by: Kees Cook <kees@kernel.org> |
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Dave Martin
|
85a7f9cbf8 |
regset: Add explicit core note name in struct user_regset
There is currently hard-coded logic spread around the tree for determining the note name for regset notes emitted in coredumps. Now that the names are declared explicitly in <uapi/elf.h>, this can be simplified. In preparation for getting rid of the special-case logic, add an explicit core_note_name field in struct user_regset for specifying the note name explicitly. To help avoid mistakes, a convenience macro USER_REGSET_NOTE_TYPE() is provided to set .core_note_type and .core_note_name based on the note type. When dumping core, use the new field to set the note name, if the regset specifies it. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kees Cook <kees@kernel.org> Cc: Akihiko Odaki <akihiko.odaki@daynix.com> Acked-by: Alexander Gordeev <agordeev@linux.ibm.com> # s390 Reviewed-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp> Link: https://lore.kernel.org/r/20250701135616.29630-3-Dave.Martin@arm.com Signed-off-by: Kees Cook <kees@kernel.org> |
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Lorenzo Stoakes
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b013ed4031 |
fs: consistently use can_mmap_file() helper
Since commit |
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Linus Torvalds
|
181d8e399f |
vfs-6.16-rc1.misc
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Merge tag 'vfs-6.16-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull misc vfs updates from Christian Brauner:
"This contains the usual selections of misc updates for this cycle.
Features:
- Use folios for symlinks in the page cache
FUSE already uses folios for its symlinks. Mirror that conversion
in the generic code and the NFS code. That lets us get rid of a few
folio->page->folio conversions in this path, and some of the few
remaining users of read_cache_page() / read_mapping_page()
- Try and make a few filesystem operations killable on the VFS
inode->i_mutex level
- Add sysctl vfs_cache_pressure_denom for bulk file operations
Some workloads need to preserve more dentries than we currently
allow through out sysctl interface
A HDFS servers with 12 HDDs per server, on a HDFS datanode startup
involves scanning all files and caching their metadata (including
dentries and inodes) in memory. Each HDD contains approximately 2
million files, resulting in a total of ~20 million cached dentries
after initialization
To minimize dentry reclamation, they set vfs_cache_pressure to 1.
Despite this configuration, memory pressure conditions can still
trigger reclamation of up to 50% of cached dentries, reducing the
cache from 20 million to approximately 10 million entries. During
the subsequent cache rebuild period, any HDFS datanode restart
operation incurs substantial latency penalties until full cache
recovery completes
To maintain service stability, more dentries need to be preserved
during memory reclamation. The current minimum reclaim ratio (1/100
of total dentries) remains too aggressive for such workload. This
patch introduces vfs_cache_pressure_denom for more granular cache
pressure control
The configuration [vfs_cache_pressure=1,
vfs_cache_pressure_denom=10000] effectively maintains the full 20
million dentry cache under memory pressure, preventing datanode
restart performance degradation
- Avoid some jumps in inode_permission() using likely()/unlikely()
- Avid a memory access which is most likely a cache miss when
descending into devcgroup_inode_permission()
- Add fastpath predicts for stat() and fdput()
- Anonymous inodes currently don't come with a proper mode causing
issues in the kernel when we want to add useful VFS debug assert.
Fix that by giving them a proper mode and masking it off when we
report it to userspace which relies on them not having any mode
- Anonymous inodes currently allow to change inode attributes because
the VFS falls back to simple_setattr() if i_op->setattr isn't
implemented. This means the ownership and mode for every single
user of anon_inode_inode can be changed. Block that as it's either
useless or actively harmful. If specific ownership is needed the
respective subsystem should allocate anonymous inodes from their
own private superblock
- Raise SB_I_NODEV and SB_I_NOEXEC on the anonymous inode superblock
- Add proper tests for anonymous inode behavior
- Make it easy to detect proper anonymous inodes and to ensure that
we can detect them in codepaths such as readahead()
Cleanups:
- Port pidfs to the new anon_inode_{g,s}etattr() helpers
- Try to remove the uselib() system call
- Add unlikely branch hint return path for poll
- Add unlikely branch hint on return path for core_sys_select
- Don't allow signals to interrupt getdents copying for fuse
- Provide a size hint to dir_context for during readdir()
- Use writeback_iter directly in mpage_writepages
- Update compression and mtime descriptions in initramfs
documentation
- Update main netfs API document
- Remove useless plus one in super_cache_scan()
- Remove unnecessary NULL-check guards during setns()
- Add separate separate {get,put}_cgroup_ns no-op cases
Fixes:
- Fix typo in root= kernel parameter description
- Use KERN_INFO for infof()|info_plog()|infofc()
- Correct comments of fs_validate_description()
- Mark an unlikely if condition with unlikely() in
vfs_parse_monolithic_sep()
- Delete macro fsparam_u32hex()
- Remove unused and problematic validate_constant_table()
- Fix potential unsigned integer underflow in fs_name()
- Make file-nr output the total allocated file handles"
* tag 'vfs-6.16-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (43 commits)
fs: Pass a folio to page_put_link()
nfs: Use a folio in nfs_get_link()
fs: Convert __page_get_link() to use a folio
fs/read_write: make default_llseek() killable
fs/open: make do_truncate() killable
fs/open: make chmod_common() and chown_common() killable
include/linux/fs.h: add inode_lock_killable()
readdir: supply dir_context.count as readdir buffer size hint
vfs: Add sysctl vfs_cache_pressure_denom for bulk file operations
fuse: don't allow signals to interrupt getdents copying
Documentation: fix typo in root= kernel parameter description
include/cgroup: separate {get,put}_cgroup_ns no-op case
kernel/nsproxy: remove unnecessary guards
fs: use writeback_iter directly in mpage_writepages
fs: remove useless plus one in super_cache_scan()
fs: add S_ANON_INODE
fs: remove uselib() system call
device_cgroup: avoid access to ->i_rdev in the common case in devcgroup_inode_permission()
fs/fs_parse: Remove unused and problematic validate_constant_table()
fs: touch up predicts in inode_permission()
...
|
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Kees Cook
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11854fe263 |
binfmt_elf: Move brk for static PIE even if ASLR disabled
In commit |
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Christian Brauner
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79beea2db0 |
fs: remove uselib() system call
This system call has been deprecated for quite a while now. Let's try and remove it from the kernel completely. Link: https://lore.kernel.org/20250415-kanufahren-besten-02ac00e6becd@brauner Acked-by: Kees Cook <kees@kernel.org> Signed-off-by: Christian Brauner <brauner@kernel.org> |
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Akihiko Odaki
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2fc4947bbd |
binfmt_elf: Use note name macros
Use note name macros to match with the userspace's expectation. Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com> Acked-by: Baoquan He <bhe@redhat.com> Reviewed-by: Dave Martin <Dave.Martin@arm.com> Link: https://lore.kernel.org/r/20250115-elf-v5-2-0f9e55bbb2fc@daynix.com Signed-off-by: Kees Cook <kees@kernel.org> |
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Amir Goldstein
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0357ef03c9 |
fs: don't block write during exec on pre-content watched files
Commit
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Christian Brauner
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3b83203538 |
Revert "fs: don't block i_writecount during exec"
This reverts commit |
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Mark Brown
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4e6e8c2b75 |
binfmt_elf: Wire up AT_HWCAP3 at AT_HWCAP4
AT_HWCAP3 and AT_HWCAP4 were recently defined for use on PowerPC in commit
|
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Linus Torvalds
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a78282e2c9 |
Revert "binfmt_elf, coredump: Log the reason of the failed core dumps"
This reverts commit
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Linus Torvalds
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667495de21 |
execve updates for v6.12-rc1
- binfmt_elf: Dump smaller VMAs first in ELF cores (Brian Mak) - binfmt_elf: mseal address zero (Jeff Xu) - binfmt_elf, coredump: Log the reason of the failed core dumps (Roman Kisel) -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQRSPkdeREjth1dHnSE2KwveOeQkuwUCZufubAAKCRA2KwveOeQk uyBPAQC2sM6j4xEEjyVkUZMmtumhyHMWtYmkqTmP8SbFn0Q3eQD/Yh9iyRng6Kmc jYm7RumqQkT+wrjXXKlazuJN9w7knAU= =UuX5 -----END PGP SIGNATURE----- Merge tag 'execve-v6.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull execve updates from Kees Cook: - binfmt_elf: Dump smaller VMAs first in ELF cores (Brian Mak) - binfmt_elf: mseal address zero (Jeff Xu) - binfmt_elf, coredump: Log the reason of the failed core dumps (Roman Kisel) * tag 'execve-v6.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: binfmt_elf: mseal address zero binfmt_elf: Dump smaller VMAs first in ELF cores binfmt_elf, coredump: Log the reason of the failed core dumps coredump: Standartize and fix logging |
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Jeff Xu
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44f65d9006 |
binfmt_elf: mseal address zero
In load_elf_binary as part of the execve(), when the current
task’s personality has MMAP_PAGE_ZERO set, the kernel allocates
one page at address 0. According to the comment:
/* Why this, you ask??? Well SVr4 maps page 0 as read-only,
and some applications "depend" upon this behavior.
Since we do not have the power to recompile these, we
emulate the SVr4 behavior. Sigh. */
At one point, Linus suggested removing this [1].
Code search in debian didn't see much use of MMAP_PAGE_ZERO [2],
it exists in util and test (rr).
Sealing this is probably safe, the comment doesn't say
the app ever wanting to change the mapping to rwx. Sealing
also ensures that never happens.
If there is a complaint, we can make this configurable.
Link: https://lore.kernel.org/lkml/CAHk-=whVa=nm_GW=NVfPHqcxDbWt4JjjK1YWb0cLjO4ZSGyiDA@mail.gmail.com/ [1]
Link: https://codesearch.debian.net/search?q=MMAP_PAGE_ZERO&literal=1&perpkg=1&page=1 [2]
Signed-off-by: Jeff Xu <jeffxu@chromium.org>
Link: https://lore.kernel.org/r/20240806214931.2198172-2-jeffxu@google.com
Signed-off-by: Kees Cook <kees@kernel.org>
|
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Roman Kisel
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fb97d2eb54 |
binfmt_elf, coredump: Log the reason of the failed core dumps
Missing, failed, or corrupted core dumps might impede crash investigations. To improve reliability of that process and consequently the programs themselves, one needs to trace the path from producing a core dumpfile to analyzing it. That path starts from the core dump file written to the disk by the kernel or to the standard input of a user mode helper program to which the kernel streams the coredump contents. There are cases where the kernel will interrupt writing the core out or produce a truncated/not-well-formed core dump without leaving a note. Add logging for the core dump collection failure paths to be able to reason what has gone wrong when the core dump is malformed or missing. Report the size of the data written to aid in diagnosing the user mode helper. Signed-off-by: Roman Kisel <romank@linux.microsoft.com> Link: https://lore.kernel.org/r/20240718182743.1959160-3-romank@linux.microsoft.com Signed-off-by: Kees Cook <kees@kernel.org> |
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Vignesh Balasubramanian
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ba386777a3 |
x86/elf: Add a new FPU buffer layout info to x86 core files
Add a new .note section containing type, size, offset and flags of every xfeature that is present. This information will be used by debuggers to understand the XSAVE layout of the machine where the core file has been dumped, and to read XSAVE registers, especially during cross-platform debugging. The XSAVE layouts of modern AMD and Intel CPUs differ, especially since Memory Protection Keys and the AVX-512 features have been inculcated into the AMD CPUs. Since AMD never adopted (and hence never left room in the XSAVE layout for) the Intel MPX feature, tools like GDB had assumed a fixed XSAVE layout matching that of Intel (based on the XCR0 mask). Hence, core dumps from AMD CPUs didn't match the known size for the XCR0 mask. This resulted in GDB and other tools not being able to access the values of the AVX-512 and PKRU registers on AMD CPUs. To solve this, an interim solution has been accepted into GDB, and is already a part of GDB 14, see https://sourceware.org/pipermail/gdb-patches/2023-March/198081.html. But it depends on heuristics based on the total XSAVE register set size and the XCR0 mask to infer the layouts of the various register blocks for core dumps, and hence, is not a foolproof mechanism to determine the layout of the XSAVE area. Therefore, add a new core dump note in order to allow GDB/LLDB and other relevant tools to determine the layout of the XSAVE area of the machine where the corefile was dumped. The new core dump note (which is being proposed as a per-process .note section), NT_X86_XSAVE_LAYOUT (0x205) contains an array of structures. Each structure describes an individual extended feature containing offset, size and flags in this format: struct x86_xfeat_component { u32 type; u32 size; u32 offset; u32 flags; }; and in an independent manner, allowing for future extensions without depending on hw arch specifics like CPUID etc. [ bp: Massage commit message, zap trailing whitespace. ] Co-developed-by: Jini Susan George <jinisusan.george@amd.com> Signed-off-by: Jini Susan George <jinisusan.george@amd.com> Co-developed-by: Borislav Petkov (AMD) <bp@alien8.de> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Signed-off-by: Vignesh Balasubramanian <vigbalas@amd.com> Link: https://lore.kernel.org/r/20240725161017.112111-2-vigbalas@amd.com |
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Linus Torvalds
|
e9e969797b |
execve fix for v6.11-rc1
- Move KUnit tests to tests/ subdirectory -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEpcP2jyKd1g9yPm4TiXL039xtwCYFAmagDLAACgkQiXL039xt wCaNChAAqV0R2sK9/C3T2X0BEJo0pslZuPZBG7zEWPxF87jfjBC47Gt+xtwxXOzG ylMwyX8xOVE+rNhxqgRDgFSdWJ/Ypv4gKypwilFFeLglN4b+PtMOepOM9MXTBVym qi8+Yv02pUnEeEXxW+Bz8xR/eB6LAkKQEs5ZodzqK9CMQnduxCfnYbKfoDlDqAkY fl7Npy+P5EwD5YFC70rA7hd7sx83UE7+hqjYXfCoVDeMYoCJXPYwIPFrENnjyJYD WFiLYXbSMFigVY3BACSNrDLUtFzIr1kaicU11crKSRayGAzHkbYCKeEj1puxEUGW dhzSfrzqcb1qYjlZE+tDgwS9KVPAk802SAf6QggjC/emeE37pCnd2lDmdXnVTe8G HUhdNaGnBGICBUOOuqdYW3ei4NidWlLRhmyniidsoxL8t0iWe4wMJn6WmOH/XRTt S5C6it2cN00GvKLlFz4TcnosXkWmjsmii5aNVctXW6CjYJpgi64QkOkFJEtqeltZ Gv/KSBU/5OihvdTLHEJTMOBGbH4NTi1D1VYZR2GlRvhy0/KHTxeDfKARTJNra4jR 76NAQlNqG1Bi50lm8Zb489WqlW38ua3rjK9zgrPSR739zN+H6jFyR57CEA7G1gX5 hlKJkrBEBalydH6dCt2qP3T9IlhB/bM/cx8wXnwK5sHVv1Kh1KI= =Kl2W -----END PGP SIGNATURE----- Merge tag 'execve-v6.11-rc1-fix1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull execve fix from Kees Cook: "This moves the exec and binfmt_elf tests out of your way and into the tests/ subdirectory, following the newly ratified KUnit naming conventions. :)" * tag 'execve-v6.11-rc1-fix1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: execve: Move KUnit tests to tests/ subdirectory |
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Kees Cook
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b6f5ee4d53 |
execve: Move KUnit tests to tests/ subdirectory
Move the exec KUnit tests into a separate directory to avoid polluting the local directory namespace. Additionally update MAINTAINERS for the new files. Reviewed-by: David Gow <davidgow@google.com> Reviewed-by: SeongJae Park <sj@kernel.org> Acked-by: Christian Brauner <brauner@kernel.org> Link: https://lore.kernel.org/r/20240720170310.it.942-kees@kernel.org Signed-off-by: Kees Cook <kees@kernel.org> |
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Linus Torvalds
|
72fda6c8e5 |
execve updates for v6.11-rc1
- Use value of kernel.randomize_va_space once per exec (Alexey Dobriyan) - Honor PT_LOAD alignment for static PIE - Make bprm->argmin only visible under CONFIG_MMU - Add KUnit testing of bprm_stack_limits() -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEpcP2jyKd1g9yPm4TiXL039xtwCYFAmaVTFAACgkQiXL039xt wCYyZw//ZcPV2hu48WqqOImL8LI9HIUaZqKQpixGQRD5VcTRb5MKg8g3Wi4EBHz+ Kg6QvTEOQdg6NbfE9fH8VIIwcp3dAxdWN6g+3A0HHDSRdb8Ye1ucnzB2kgmEkM1l huBRn5tnoS0vn2fxafu1O5tj330kKAvTsemsy316cxmbKNs7ckHdfwuVgZHcuyEt OrOA3ZSTWwjkSiA9tatsi5iAQ34tQYGwDEosf06avlnPkQqsRzn3wNlohAPjQF6V kjRfX/Mxz2EHa0mjXy2OkhNyPSn6wu0OcmF0ympySHzxm726uRggG+olT5ziUc+2 DW6Gz6TJ1P8Gu+uTEoz6AY+l5Bpo9ZLYSBm+Mp88sxAT6+Xcc68XeZsFZHmefJzs 6g6EdmwhDEP/Xd3sIsNphdkS5q1RMgc7tdAtyK8GCaACsHUlU4CfzRYh2mWxpIg6 hA7oM5KF9FuToLtaIS6K/yYQIVsTKAaA7t+5K/a1RUyKzcJ0O7UpMx1oEge2sPEK RnETCYhQs0Cxm11iJ/eqEFzWm0Puxjsjz/P/j5H5U8usx9VUoz0HuS91fNEIY3S9 y7bn09wxuUv4QddKYgltkurxCCB//Nv7jPYo96pKIW3T56XkfsrYLvNH2W95cCNz OMvZImA1J/vQubSODrgeQsfMRsaJodHU3acWyYQ90HmmoWx4JS4= =bO7x -----END PGP SIGNATURE----- Merge tag 'execve-v6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull execve updates from Kees Cook: - Use value of kernel.randomize_va_space once per exec (Alexey Dobriyan) - Honor PT_LOAD alignment for static PIE - Make bprm->argmin only visible under CONFIG_MMU - Add KUnit testing of bprm_stack_limits() * tag 'execve-v6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: exec: Avoid pathological argc, envc, and bprm->p values execve: Keep bprm->argmin behind CONFIG_MMU ELF: fix kernel.randomize_va_space double read exec: Add KUnit test for bprm_stack_limits() binfmt_elf: Honor PT_LOAD alignment for static PIE binfmt_elf: Calculate total_size earlier selftests/exec: Build both static and non-static load_address tests |
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Alexey Dobriyan
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2a97388a80 |
ELF: fix kernel.randomize_va_space double read
ELF loader uses "randomize_va_space" twice. It is sysctl and can change at any moment, so 2 loads could see 2 different values in theory with unpredictable consequences. Issue exactly one load for consistent value across one exec. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Link: https://lore.kernel.org/r/3329905c-7eb8-400a-8f0a-d87cff979b5b@p183 Signed-off-by: Kees Cook <kees@kernel.org> |
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Kees Cook
|
3545deff0e |
binfmt_elf: Honor PT_LOAD alignment for static PIE
The p_align values in PT_LOAD were ignored for static PIE executables (i.e. ET_DYN without PT_INTERP). This is because there is no way to request a non-fixed mmap region with a specific alignment. ET_DYN with PT_INTERP uses a separate base address (ELF_ET_DYN_BASE) and binfmt_elf performs the ASLR itself, which means it can also apply alignment. For the mmap region, the address selection happens deep within the vm_mmap() implementation (when the requested address is 0). The earlier attempt to implement this: commit |
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Kees Cook
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2d4cf7b190 |
binfmt_elf: Calculate total_size earlier
In preparation to support PT_LOAD with large p_align values on non-PT_INTERP ET_DYN executables (i.e. "static pie"), we'll need to use the total_size details earlier. Move this separately now to make the next patch more readable. As total_size and load_bias are currently calculated separately, this has no behavioral impact. Link: https://lore.kernel.org/r/20240508173149.677910-2-keescook@chromium.org Signed-off-by: Kees Cook <kees@kernel.org> |
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Christian Brauner
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2a010c4128 |
fs: don't block i_writecount during exec
Back in 2021 we already discussed removing deny_write_access() for
executables. Back then I was hesistant because I thought that this might
cause issues in userspace. But even back then I had started taking some
notes on what could potentially depend on this and I didn't come up with
a lot so I've changed my mind and I would like to try this.
Here are some of the notes that I took:
(1) The deny_write_access() mechanism is causing really pointless issues
such as [1]. If a thread in a thread-group opens a file writable,
then writes some stuff, then closing the file descriptor and then
calling execve() they can fail the execve() with ETXTBUSY because
another thread in the thread-group could have concurrently called
fork(). Multi-threaded libraries such as go suffer from this.
(2) There are userspace attacks that rely on overwriting the binary of a
running process. These attacks are _mitigated_ but _not at all
prevented_ from ocurring by the deny_write_access() mechanism.
I'll go over some details. The clearest example of such attacks was
the attack against runC in CVE-2019-5736 (cf. [3]).
An attack could compromise the runC host binary from inside a
_privileged_ runC container. The malicious binary could then be used
to take over the host.
(It is crucial to note that this attack is _not_ possible with
unprivileged containers. IOW, the setup here is already insecure.)
The attack can be made when attaching to a running container or when
starting a container running a specially crafted image. For example,
when runC attaches to a container the attacker can trick it into
executing itself.
This could be done by replacing the target binary inside the
container with a custom binary pointing back at the runC binary
itself. As an example, if the target binary was /bin/bash, this
could be replaced with an executable script specifying the
interpreter path #!/proc/self/exe.
As such when /bin/bash is executed inside the container, instead the
target of /proc/self/exe will be executed. That magic link will
point to the runc binary on the host. The attacker can then proceed
to write to the target of /proc/self/exe to try and overwrite the
runC binary on the host.
However, this will not succeed because of deny_write_access(). Now,
one might think that this would prevent the attack but it doesn't.
To overcome this, the attacker has multiple ways:
* Open a file descriptor to /proc/self/exe using the O_PATH flag and
then proceed to reopen the binary as O_WRONLY through
/proc/self/fd/<nr> and try to write to it in a busy loop from a
separate process. Ultimately it will succeed when the runC binary
exits. After this the runC binary is compromised and can be used
to attack other containers or the host itself.
* Use a malicious shared library annotating a function in there with
the constructor attribute making the malicious function run as an
initializor. The malicious library will then open /proc/self/exe
for creating a new entry under /proc/self/fd/<nr>. It'll then call
exec to a) force runC to exit and b) hand the file descriptor off
to a program that then reopens /proc/self/fd/<nr> for writing
(which is now possible because runC has exited) and overwriting
that binary.
To sum up: the deny_write_access() mechanism doesn't prevent such
attacks in insecure setups. It just makes them minimally harder.
That's all.
The only way back then to prevent this is to create a temporary copy
of the calling binary itself when it starts or attaches to
containers. So what I did back then for LXC (and Aleksa for runC)
was to create an anonymous, in-memory file using the memfd_create()
system call and to copy itself into the temporary in-memory file,
which is then sealed to prevent further modifications. This sealed,
in-memory file copy is then executed instead of the original on-disk
binary.
Any compromising write operations from a privileged container to the
host binary will then write to the temporary in-memory binary and
not to the host binary on-disk, preserving the integrity of the host
binary. Also as the temporary, in-memory binary is sealed, writes to
this will also fail.
The point is that deny_write_access() is uselss to prevent these
attacks.
(3) Denying write access to an inode because it's currently used in an
exec path could easily be done on an LSM level. It might need an
additional hook but that should be about it.
(4) The MAP_DENYWRITE flag for mmap() has been deprecated a long time
ago so while we do protect the main executable the bigger portion of
the things you'd think need protecting such as the shared libraries
aren't. IOW, we let anyone happily overwrite shared libraries.
(5) We removed all remaining uses of VM_DENYWRITE in [2]. That means:
(5.1) We removed the legacy uselib() protection for preventing
overwriting of shared libraries. Nobody cared in 3 years.
(5.2) We allow write access to the elf interpreter after exec
completed treating it on a par with shared libraries.
Yes, someone in userspace could potentially be relying on this. It's not
completely out of the realm of possibility but let's find out if that's
actually the case and not guess.
Link: https://github.com/golang/go/issues/22315 [1]
Link:
|
||
|
Linus Torvalds
|
eb6a9339ef |
Mainly singleton patches, documented in their respective changelogs.
Notable series include:
- Some maintenance and performance work for ocfs2 in Heming Zhao's
series "improve write IO performance when fragmentation is high".
- Some ocfs2 bugfixes from Su Yue in the series "ocfs2 bugs fixes
exposed by fstests".
- kfifo header rework from Andy Shevchenko in the series "kfifo: Clean
up kfifo.h".
- GDB script fixes from Florian Rommel in the series "scripts/gdb: Fixes
for $lx_current and $lx_per_cpu".
- After much discussion, a coding-style update from Barry Song
explaining one reason why inline functions are preferred over macros.
The series is "codingstyle: avoid unused parameters for a function-like
macro".
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Merge tag 'mm-nonmm-stable-2024-05-19-11-56' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull non-mm updates from Andrew Morton:
"Mainly singleton patches, documented in their respective changelogs.
Notable series include:
- Some maintenance and performance work for ocfs2 in Heming Zhao's
series "improve write IO performance when fragmentation is high".
- Some ocfs2 bugfixes from Su Yue in the series "ocfs2 bugs fixes
exposed by fstests".
- kfifo header rework from Andy Shevchenko in the series "kfifo:
Clean up kfifo.h".
- GDB script fixes from Florian Rommel in the series "scripts/gdb:
Fixes for $lx_current and $lx_per_cpu".
- After much discussion, a coding-style update from Barry Song
explaining one reason why inline functions are preferred over
macros. The series is "codingstyle: avoid unused parameters for a
function-like macro""
* tag 'mm-nonmm-stable-2024-05-19-11-56' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (62 commits)
fs/proc: fix softlockup in __read_vmcore
nilfs2: convert BUG_ON() in nilfs_finish_roll_forward() to WARN_ON()
scripts: checkpatch: check unused parameters for function-like macro
Documentation: coding-style: ask function-like macros to evaluate parameters
nilfs2: use __field_struct() for a bitwise field
selftests/kcmp: remove unused open mode
nilfs2: remove calls to folio_set_error() and folio_clear_error()
kernel/watchdog_perf.c: tidy up kerneldoc
watchdog: allow nmi watchdog to use raw perf event
watchdog: handle comma separated nmi_watchdog command line
nilfs2: make superblock data array index computation sparse friendly
squashfs: remove calls to set the folio error flag
squashfs: convert squashfs_symlink_read_folio to use folio APIs
scripts/gdb: fix detection of current CPU in KGDB
scripts/gdb: make get_thread_info accept pointers
scripts/gdb: fix parameter handling in $lx_per_cpu
scripts/gdb: fix failing KGDB detection during probe
kfifo: don't use "proxy" headers
media: stih-cec: add missing io.h
media: rc: add missing io.h
...
|
||
Allen Pais
|
4bbf9c3b53 |
fs/coredump: Enable dynamic configuration of max file note size
Introduce the capability to dynamically configure the maximum file note size for ELF core dumps via sysctl. Why is this being done? We have observed that during a crash when there are more than 65k mmaps in memory, the existing fixed limit on the size of the ELF notes section becomes a bottleneck. The notes section quickly reaches its capacity, leading to incomplete memory segment information in the resulting coredump. This truncation compromises the utility of the coredumps, as crucial information about the memory state at the time of the crash might be omitted. This enhancement removes the previous static limit of 4MB, allowing system administrators to adjust the size based on system-specific requirements or constraints. Eg: $ sysctl -a | grep core_file_note_size_limit kernel.core_file_note_size_limit = 4194304 $ sysctl -n kernel.core_file_note_size_limit 4194304 $echo 519304 > /proc/sys/kernel/core_file_note_size_limit $sysctl -n kernel.core_file_note_size_limit 519304 Attempting to write beyond the ceiling value of 16MB $echo 17194304 > /proc/sys/kernel/core_file_note_size_limit bash: echo: write error: Invalid argument Signed-off-by: Vijay Nag <nagvijay@microsoft.com> Signed-off-by: Allen Pais <apais@linux.microsoft.com> Link: https://lore.kernel.org/r/20240506193700.7884-1-apais@linux.microsoft.com Signed-off-by: Kees Cook <keescook@chromium.org> |
||
Douglas Anderson
|
6b839b3b76 |
regset: use kvzalloc() for regset_get_alloc()
While browsing through ChromeOS crash reports, I found one with an
allocation failure that looked like this:
chrome: page allocation failure: order:7,
mode:0x40dc0(GFP_KERNEL|__GFP_COMP|__GFP_ZERO),
nodemask=(null),cpuset=urgent,mems_allowed=0
CPU: 7 PID: 3295 Comm: chrome Not tainted
5.15.133-20574-g8044615ac35c #1 (HASH:1162 1)
Hardware name: Google Lazor (rev3 - 8) with KB Backlight (DT)
Call trace:
...
warn_alloc+0x104/0x174
__alloc_pages+0x5f0/0x6e4
kmalloc_order+0x44/0x98
kmalloc_order_trace+0x34/0x124
__kmalloc+0x228/0x36c
__regset_get+0x68/0xcc
regset_get_alloc+0x1c/0x28
elf_core_dump+0x3d8/0xd8c
do_coredump+0xeb8/0x1378
get_signal+0x14c/0x804
...
An order 7 allocation is (1 << 7) contiguous pages, or 512K. It's not
a surprise that this allocation failed on a system that's been running
for a while.
More digging showed that it was fairly easy to see the order 7
allocation by just sending a SIGQUIT to chrome (or other processes) to
generate a core dump. The actual amount being allocated was 279,584
bytes and it was for "core_note_type" NT_ARM_SVE.
There was quite a bit of discussion [1] on the mailing lists in
response to my v1 patch attempting to switch to vmalloc. The overall
conclusion was that we could likely reduce the 279,584 byte allocation
by quite a bit and Mark Brown has sent a patch to that effect [2].
However even with the 279,584 byte allocation gone there are still
65,552 byte allocations. These are just barely more than the 65,536
bytes and thus would require an order 5 allocation.
An order 5 allocation is still something to avoid unless necessary and
nothing needs the memory here to be contiguous. Change the allocation
to kvzalloc() which should still be efficient for small allocations
but doesn't force the memory subsystem to work hard (and maybe fail)
at getting a large contiguous chunk.
[1] https://lore.kernel.org/r/20240201171159.1.Id9ad163b60d21c9e56c2d686b0cc9083a8ba7924@changeid
[2] https://lore.kernel.org/r/20240203-arm64-sve-ptrace-regset-size-v1-1-2c3ba1386b9e@kernel.org
Link: https://lkml.kernel.org/r/20240205092626.v2.1.Id9ad163b60d21c9e56c2d686b0cc9083a8ba7924@changeid
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dave Martin <Dave.Martin@arm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
||
Kees Cook
|
2a5eb99955 |
binfmt_elf: Leave a gap between .bss and brk
Currently the brk starts its randomization immediately after .bss, which means there is a chance that when the random offset is 0, linear overflows from .bss can reach into the brk area. Leave at least a single page gap between .bss and brk (when it has not already been explicitly relocated into the mmap range). Reported-by: <y0un9n132@gmail.com> Closes: https://lore.kernel.org/linux-hardening/CA+2EKTVLvc8hDZc+2Yhwmus=dzOUG5E4gV7ayCbu0MPJTZzWkw@mail.gmail.com/ Link: https://lore.kernel.org/r/20240217062545.1631668-2-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> |
||
|
Kees Cook
|
f9c0a39d95 |
binfmt_elf: Only report padzero() errors when PROT_WRITE
Errors with padzero() should be caught unless we're expecting a pathological (non-writable) segment. Report -EFAULT only when PROT_WRITE is present. Additionally add some more documentation to padzero(), elf_map(), and elf_load(). Cc: Eric Biederman <ebiederm@xmission.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <brauner@kernel.org> Cc: linux-fsdevel@vger.kernel.org Cc: linux-mm@kvack.org Suggested-by: Eric Biederman <ebiederm@xmission.com> Tested-by: Pedro Falcato <pedro.falcato@gmail.com> Signed-off-by: Sebastian Ott <sebott@redhat.com> Link: https://lore.kernel.org/r/20230929032435.2391507-5-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> |
||
|
Kees Cook
|
d5ca24f639 |
binfmt_elf: Use elf_load() for library
While load_elf_library() is a libc5-ism, we can still replace most of its contents with elf_load() as well, further simplifying the code. Some historical context: - libc4 was a.out and used uselib (a.out support has been removed) - libc5 was ELF and used uselib (there may still be users) - libc6 is ELF and has never used uselib Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <brauner@kernel.org> Cc: linux-fsdevel@vger.kernel.org Cc: linux-mm@kvack.org Suggested-by: Eric Biederman <ebiederm@xmission.com> Tested-by: Pedro Falcato <pedro.falcato@gmail.com> Signed-off-by: Sebastian Ott <sebott@redhat.com> Link: https://lore.kernel.org/r/20230929032435.2391507-4-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> |
||
|
Kees Cook
|
8b04d32678 |
binfmt_elf: Use elf_load() for interpreter
Handle arbitrary memsz>filesz in interpreter ELF segments, instead of only supporting it in the last segment (which is expected to be the BSS). Cc: Eric Biederman <ebiederm@xmission.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <brauner@kernel.org> Cc: linux-fsdevel@vger.kernel.org Cc: linux-mm@kvack.org Reported-by: Pedro Falcato <pedro.falcato@gmail.com> Closes: https://lore.kernel.org/lkml/20221106021657.1145519-1-pedro.falcato@gmail.com/ Tested-by: Pedro Falcato <pedro.falcato@gmail.com> Signed-off-by: Sebastian Ott <sebott@redhat.com> Link: https://lore.kernel.org/r/20230929032435.2391507-3-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> |
||
|
Kees Cook
|
8ed2ef21ff |
binfmt_elf: elf_bss no longer used by load_elf_binary()
With the BSS handled generically via the new filesz/memsz mismatch handling logic in elf_load(), elf_bss no longer needs to be tracked. Drop the variable. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <brauner@kernel.org> Cc: linux-fsdevel@vger.kernel.org Cc: linux-mm@kvack.org Suggested-by: Eric Biederman <ebiederm@xmission.com> Tested-by: Pedro Falcato <pedro.falcato@gmail.com> Signed-off-by: Sebastian Ott <sebott@redhat.com> Link: https://lore.kernel.org/r/20230929032435.2391507-2-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> |
||
Eric W. Biederman
|
585a018627 |
binfmt_elf: Support segments with 0 filesz and misaligned starts
Implement a helper elf_load() that wraps elf_map() and performs all of the necessary work to ensure that when "memsz > filesz" the bytes described by "memsz > filesz" are zeroed. An outstanding issue is if the first segment has filesz 0, and has a randomized location. But that is the same as today. In this change I replaced an open coded padzero() that did not clear all of the way to the end of the page, with padzero() that does. I also stopped checking the return of padzero() as there is at least one known case where testing for failure is the wrong thing to do. It looks like binfmt_elf_fdpic may have the proper set of tests for when error handling can be safely completed. I found a couple of commits in the old history https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git, that look very interesting in understanding this code. commit 39b56d902bf3 ("[PATCH] binfmt_elf: clearing bss may fail") commit c6e2227e4a3e ("[SPARC64]: Missing user access return value checks in fs/binfmt_elf.c and fs/compat.c") commit 5bf3be033f50 ("v2.4.10.1 -> v2.4.10.2") Looking at commit 39b56d902bf3 ("[PATCH] binfmt_elf: clearing bss may fail"): > commit 39b56d902bf35241e7cba6cc30b828ed937175ad > Author: Pavel Machek <pavel@ucw.cz> > Date: Wed Feb 9 22:40:30 2005 -0800 > > [PATCH] binfmt_elf: clearing bss may fail > > So we discover that Borland's Kylix application builder emits weird elf > files which describe a non-writeable bss segment. > > So remove the clear_user() check at the place where we zero out the bss. I > don't _think_ there are any security implications here (plus we've never > checked that clear_user() return value, so whoops if it is a problem). > > Signed-off-by: Pavel Machek <pavel@suse.cz> > Signed-off-by: Andrew Morton <akpm@osdl.org> > Signed-off-by: Linus Torvalds <torvalds@osdl.org> It seems pretty clear that binfmt_elf_fdpic with skipping clear_user() for non-writable segments and otherwise calling clear_user(), aka padzero(), and checking it's return code is the right thing to do. I just skipped the error checking as that avoids breaking things. And notably, it looks like Borland's Kylix died in 2005 so it might be safe to just consider read-only segments with memsz > filesz an error. Reported-by: Sebastian Ott <sebott@redhat.com> Reported-by: Thomas Weißschuh <linux@weissschuh.net> Closes: https://lkml.kernel.org/r/20230914-bss-alloc-v1-1-78de67d2c6dd@weissschuh.net Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Link: https://lore.kernel.org/r/87sf71f123.fsf@email.froward.int.ebiederm.org Tested-by: Pedro Falcato <pedro.falcato@gmail.com> Signed-off-by: Sebastian Ott <sebott@redhat.com> Link: https://lore.kernel.org/r/20230929032435.2391507-1-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> |
||
|
Linus Torvalds
|
9471f1f2f5 |
Merge branch 'expand-stack'
This modifies our user mode stack expansion code to always take the
mmap_lock for writing before modifying the VM layout.
It's actually something we always technically should have done, but
because we didn't strictly need it, we were being lazy ("opportunistic"
sounds so much better, doesn't it?) about things, and had this hack in
place where we would extend the stack vma in-place without doing the
proper locking.
And it worked fine. We just needed to change vm_start (or, in the case
of grow-up stacks, vm_end) and together with some special ad-hoc locking
using the anon_vma lock and the mm->page_table_lock, it all was fairly
straightforward.
That is, it was all fine until Ruihan Li pointed out that now that the
vma layout uses the maple tree code, we *really* don't just change
vm_start and vm_end any more, and the locking really is broken. Oops.
It's not actually all _that_ horrible to fix this once and for all, and
do proper locking, but it's a bit painful. We have basically three
different cases of stack expansion, and they all work just a bit
differently:
- the common and obvious case is the page fault handling. It's actually
fairly simple and straightforward, except for the fact that we have
something like 24 different versions of it, and you end up in a maze
of twisty little passages, all alike.
- the simplest case is the execve() code that creates a new stack.
There are no real locking concerns because it's all in a private new
VM that hasn't been exposed to anybody, but lockdep still can end up
unhappy if you get it wrong.
- and finally, we have GUP and page pinning, which shouldn't really be
expanding the stack in the first place, but in addition to execve()
we also use it for ptrace(). And debuggers do want to possibly access
memory under the stack pointer and thus need to be able to expand the
stack as a special case.
None of these cases are exactly complicated, but the page fault case in
particular is just repeated slightly differently many many times. And
ia64 in particular has a fairly complicated situation where you can have
both a regular grow-down stack _and_ a special grow-up stack for the
register backing store.
So to make this slightly more manageable, the bulk of this series is to
first create a helper function for the most common page fault case, and
convert all the straightforward architectures to it.
Thus the new 'lock_mm_and_find_vma()' helper function, which ends up
being used by x86, arm, powerpc, mips, riscv, alpha, arc, csky, hexagon,
loongarch, nios2, sh, sparc32, and xtensa. So we not only convert more
than half the architectures, we now have more shared code and avoid some
of those twisty little passages.
And largely due to this common helper function, the full diffstat of
this series ends up deleting more lines than it adds.
That still leaves eight architectures (ia64, m68k, microblaze, openrisc,
parisc, s390, sparc64 and um) that end up doing 'expand_stack()'
manually because they are doing something slightly different from the
normal pattern. Along with the couple of special cases in execve() and
GUP.
So there's a couple of patches that first create 'locked' helper
versions of the stack expansion functions, so that there's a obvious
path forward in the conversion. The execve() case is then actually
pretty simple, and is a nice cleanup from our old "grow-up stackls are
special, because at execve time even they grow down".
The #ifdef CONFIG_STACK_GROWSUP in that code just goes away, because
it's just more straightforward to write out the stack expansion there
manually, instead od having get_user_pages_remote() do it for us in some
situations but not others and have to worry about locking rules for GUP.
And the final step is then to just convert the remaining odd cases to a
new world order where 'expand_stack()' is called with the mmap_lock held
for reading, but where it might drop it and upgrade it to a write, only
to return with it held for reading (in the success case) or with it
completely dropped (in the failure case).
In the process, we remove all the stack expansion from GUP (where
dropping the lock wouldn't be ok without special rules anyway), and add
it in manually to __access_remote_vm() for ptrace().
Thanks to Adrian Glaubitz and Frank Scheiner who tested the ia64 cases.
Everything else here felt pretty straightforward, but the ia64 rules for
stack expansion are really quite odd and very different from everything
else. Also thanks to Vegard Nossum who caught me getting one of those
odd conditions entirely the wrong way around.
Anyway, I think I want to actually move all the stack expansion code to
a whole new file of its own, rather than have it split up between
mm/mmap.c and mm/memory.c, but since this will have to be backported to
the initial maple tree vma introduction anyway, I tried to keep the
patches _fairly_ minimal.
Also, while I don't think it's valid to expand the stack from GUP, the
final patch in here is a "warn if some crazy GUP user wants to try to
expand the stack" patch. That one will be reverted before the final
release, but it's left to catch any odd cases during the merge window
and release candidates.
Reported-by: Ruihan Li <lrh2000@pku.edu.cn>
* branch 'expand-stack':
gup: add warning if some caller would seem to want stack expansion
mm: always expand the stack with the mmap write lock held
execve: expand new process stack manually ahead of time
mm: make find_extend_vma() fail if write lock not held
powerpc/mm: convert coprocessor fault to lock_mm_and_find_vma()
mm/fault: convert remaining simple cases to lock_mm_and_find_vma()
arm/mm: Convert to using lock_mm_and_find_vma()
riscv/mm: Convert to using lock_mm_and_find_vma()
mips/mm: Convert to using lock_mm_and_find_vma()
powerpc/mm: Convert to using lock_mm_and_find_vma()
arm64/mm: Convert to using lock_mm_and_find_vma()
mm: make the page fault mmap locking killable
mm: introduce new 'lock_mm_and_find_vma()' page fault helper
|
||
|
Linus Torvalds
|
8d7071af89 |
mm: always expand the stack with the mmap write lock held
This finishes the job of always holding the mmap write lock when extending the user stack vma, and removes the 'write_locked' argument from the vm helper functions again. For some cases, we just avoid expanding the stack at all: drivers and page pinning really shouldn't be extending any stacks. Let's see if any strange users really wanted that. It's worth noting that architectures that weren't converted to the new lock_mm_and_find_vma() helper function are left using the legacy "expand_stack()" function, but it has been changed to drop the mmap_lock and take it for writing while expanding the vma. This makes it fairly straightforward to convert the remaining architectures. As a result of dropping and re-taking the lock, the calling conventions for this function have also changed, since the old vma may no longer be valid. So it will now return the new vma if successful, and NULL - and the lock dropped - if the area could not be extended. Tested-by: Vegard Nossum <vegard.nossum@oracle.com> Tested-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> # ia64 Tested-by: Frank Scheiner <frank.scheiner@web.de> # ia64 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
Liam R. Howlett
|
f440fa1ac9 |
mm: make find_extend_vma() fail if write lock not held
Make calls to extend_vma() and find_extend_vma() fail if the write lock is required. To avoid making this a flag-day event, this still allows the old read-locking case for the trivial situations, and passes in a flag to say "is it write-locked". That way write-lockers can say "yes, I'm being careful", and legacy users will continue to work in all the common cases until they have been fully converted to the new world order. Co-Developed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |