kernel/git/stable/linux.git/mm/kasan/quarantine.c, branch master

kasan: fix quarantine_size accounting during cache removal

2026-08-25T01:43:21+00:00

quarantine_size tracks the total number of bytes stored in global_quarantine[]. It is incremented when per-CPU quarantine objects are moved into the global quarantine and decremented when a global batch is evicted by kasan_quarantine_reduce(). kasan_quarantine_remove_cache() also removes objects from the global quarantine. qlist_move_cache() rebuilds the source batch and updates its .bytes field, but quarantine_size is not adjusted accordingly. As a result, quarantine_size remains over-counted by the size of the removed objects. The stale accounting accumulates across cache removals. Once the inflated value exceeds quarantine_max_size, kasan_quarantine_reduce() can evict a batch even though the actual number of bytes in global_quarantine[] is still below quarantine_max_size, shortening the quarantine window. Fix the accounting by recording each batch's size before qlist_move_cache() and subtracting the number of bytes actually removed from quarantine_size while holding quarantine_lock. A KUnit reproducer used during testing observed the over-count grow by 4698864 bytes after one kasan_quarantine_remove_cache() call with the fix reverted. With this change applied, the over-count did not grow. Link: https://lore.kernel.org/20260811073332.1351893-1-sh_def@163.com Fixes: 64abdcb24351 ("kasan: eliminate long stalls during quarantine reduction") Signed-off-by: Hui Su Reported-by: Sashiko Closes: https://sashiko.dev/#/patchset/20260808031459.3032812-1-sh_def%40163.com Reviewed-by: Andrey Ryabinin Cc: Alexander Potapenko Cc: Andrey Konovalov Cc: Dmitry Vyukov Cc: Vincenzo Frascino Signed-off-by: Andrew Morton

kasan: fix cache shrink race with CPU hotplug

2026-08-25T01:43:16+00:00

kasan_quarantine_remove_cache() first invokes per_cpu_remove_cache() on all online CPUs. Each callback moves objects belonging to the cache from cpu_quarantine to the CPU's shrink_qlist, where they can later be freed from task context. kmem_cache_destroy() invokes the quarantine removal path while holding cpus_read_lock(), but kmem_cache_shrink() does not. The latter can therefore race with CPU offlining as follows: kmem_cache_shrink() CPU hotplug ------------------- ----------- on_each_cpu() CPU1 moves objects to CPU1's shrink_qlist on_each_cpu() returns CPU1 goes offline kasan_cpu_offline() drains cpu_quarantine leaves shrink_qlist untouched for_each_online_cpu() skips CPU1 The objects left on CPU1's shrink_qlist are not returned to the slab allocator. This may prevent kmem_cache_shrink() from releasing slabs that would otherwise become empty. If CPU1 remains offline, a later kmem_cache_destroy() also skips the list and can report that the cache still contains objects. An intermittent occurrence was observed with a virtio-9p filesystem. The mount and umount commands both returned 0, but the kernel logged the following during the userspace-triggered teardown: [ 2994.380134][ T111] BUG 9p-fcall-cache-1 (Tainted: G B ): Objects remaining on __kmem_cache_shutdown() [ 2994.381140][ T111] Object 0xff11000004361118 @offset=4376 [ 2994.381607][ T111] Allocated in p9_fcall_init+0x201/0x400 age=19564 cpu=1 pid=104 [ 2994.382591][ T111] p9_fcall_init+0x201/0x400 [ 2994.382810][ T111] p9_tag_alloc+0x12f/0x700 [ 2994.382982][ T111] p9_client_prepare_req+0x102/0x3e0 [ 2994.383165][ T111] p9_client_rpc+0x1ab/0xa50 [ 2994.383334][ T111] p9_client_getattr_dotl+0xb0/0x1a0 [ 2994.383515][ T111] v9fs_vfs_getattr_dotl+0x115/0x360 [ 2994.383719][ T111] vfs_getattr_nosec+0x22c/0x3a0 [ 2994.383910][ T111] vfs_statx+0xd7/0x170 [ 2994.384062][ T111] vfs_fstatat+0x45/0x80 [ 2994.384215][ T111] __do_sys_newfstatat+0x84/0xe0 [ 2994.384386][ T111] do_syscall_64+0x115/0x6a0 [ 2994.384566][ T111] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 2994.399720][ T111] WARNING: mm/slub.c:1244 at __kmem_cache_shutdown+0x363/0x500, CPU#0: busybox/111 [ 2994.405655][ T111] Call Trace: [ 2994.406325][ T111] kmem_cache_destroy+0x73/0x1b0 [ 2994.406630][ T111] p9_client_destroy+0x271/0x3c0 [ 2994.407210][ T111] v9fs_session_close+0x3c/0x260 [ 2994.407409][ T111] v9fs_kill_super+0x48/0x90 [ 2994.407584][ T111] deactivate_locked_super+0xa3/0x160 [ 2994.407778][ T111] cleanup_mnt+0x1dd/0x3e0 Thus, a successful umount left objects in the 9p fcall cache and prevented the cache from being destroyed cleanly. Per-CPU shrink_qlist storage exists for every possible CPU, and each list is protected by its own raw spinlock. Iterate over possible CPUs so that a list populated before its CPU went offline is drained as well. for_each_possible_cpu() can do more work than for_each_online_cpu(), but this change only affects CONFIG_KASAN_GENERIC kernels. The extra work is limited to cache shrink and cache destruction paths and does not affect the normal allocation/free fast path. It adds one raw-spinlock-protected scan of each possible CPU's shrink list. These lists are normally empty; a non-empty list is traversed to remove objects belonging to the cache being shrunk or destroyed. Link: https://lore.kernel.org/20260808031459.3032812-1-sh_def@163.com Fixes: 07d067e4f2ce ("kasan: fix sleeping function called from invalid context on RT kernel") Signed-off-by: Hui Su Reviewed-by: Andrey Ryabinin Cc: Alexander Potapenko Cc: Andrey Konovalov Cc: Dmitry Vyukov Cc: Vincenzo Frascino Cc: "Zhang, Qiang1" Cc: Signed-off-by: Andrew Morton

kasan: revert eviction of stack traces in generic mode

2024-02-24T01:27:12+00:00

This partially reverts commits cc478e0b6bdf, 63b85ac56a64, 08d7c94d9635, a414d4286f34, and 773688a6cb24 to make use of variable-sized stack depot records, since eviction of stack entries from stack depot forces fixed- sized stack records. Care was taken to retain the code cleanups by the above commits. Eviction was added to generic KASAN as a response to alleviating the additional memory usage from fixed-sized stack records, but this still uses more memory than previously. With the re-introduction of variable-sized records for stack depot, we can just switch back to non-evictable stack records again, and return back to the previous performance and memory usage baseline. Before (observed after a KASAN kernel boot): pools: 597 refcounted_allocations: 17547 refcounted_frees: 6477 refcounted_in_use: 11070 freelist_size: 3497 persistent_count: 12163 persistent_bytes: 1717008 After: pools: 319 refcounted_allocations: 0 refcounted_frees: 0 refcounted_in_use: 0 freelist_size: 0 persistent_count: 29397 persistent_bytes: 5183536 As can be seen from the counters, with a generic KASAN config, refcounted allocations and evictions are no longer used. Due to using variable-sized records, I observe a reduction of 278 stack depot pools (saving 4448 KiB) with my test setup. Link: https://lkml.kernel.org/r/20240129100708.39460-2-elver@google.com Fixes: cc478e0b6bdf ("kasan: avoid resetting aux_lock") Fixes: 63b85ac56a64 ("kasan: stop leaking stack trace handles") Fixes: 08d7c94d9635 ("kasan: memset free track in qlink_free") Fixes: a414d4286f34 ("kasan: handle concurrent kasan_record_aux_stack calls") Fixes: 773688a6cb24 ("kasan: use stack_depot_put for Generic mode") Signed-off-by: Marco Elver Reviewed-by: Andrey Konovalov Tested-by: Mikhail Gavrilov Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Andrey Ryabinin Cc: Vincenzo Frascino Cc: Vlastimil Babka Signed-off-by: Andrew Morton

Merge tag 'mm-stable-2024-01-08-15-31' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2024-01-09T19:18:47+00:00

Pull MM updates from Andrew Morton: "Many singleton patches against the MM code. The patch series which are included in this merge do the following: - Peng Zhang has done some mapletree maintainance work in the series 'maple_tree: add mt_free_one() and mt_attr() helpers' 'Some cleanups of maple tree' - In the series 'mm: use memmap_on_memory semantics for dax/kmem' Vishal Verma has altered the interworking between memory-hotplug and dax/kmem so that newly added 'device memory' can more easily have its memmap placed within that newly added memory. - Matthew Wilcox continues folio-related work (including a few fixes) in the patch series 'Add folio_zero_tail() and folio_fill_tail()' 'Make folio_start_writeback return void' 'Fix fault handler's handling of poisoned tail pages' 'Convert aops->error_remove_page to ->error_remove_folio' 'Finish two folio conversions' 'More swap folio conversions' - Kefeng Wang has also contributed folio-related work in the series 'mm: cleanup and use more folio in page fault' - Jim Cromie has improved the kmemleak reporting output in the series 'tweak kmemleak report format'. - In the series 'stackdepot: allow evicting stack traces' Andrey Konovalov to permits clients (in this case KASAN) to cause eviction of no longer needed stack traces. - Charan Teja Kalla has fixed some accounting issues in the page allocator's atomic reserve calculations in the series 'mm: page_alloc: fixes for high atomic reserve caluculations'. - Dmitry Rokosov has added to the samples/ dorectory some sample code for a userspace memcg event listener application. See the series 'samples: introduce cgroup events listeners'. - Some mapletree maintanance work from Liam Howlett in the series 'maple_tree: iterator state changes'. - Nhat Pham has improved zswap's approach to writeback in the series 'workload-specific and memory pressure-driven zswap writeback'. - DAMON/DAMOS feature and maintenance work from SeongJae Park in the series 'mm/damon: let users feed and tame/auto-tune DAMOS' 'selftests/damon: add Python-written DAMON functionality tests' 'mm/damon: misc updates for 6.8' - Yosry Ahmed has improved memcg's stats flushing in the series 'mm: memcg: subtree stats flushing and thresholds'. - In the series 'Multi-size THP for anonymous memory' Ryan Roberts has added a runtime opt-in feature to transparent hugepages which improves performance by allocating larger chunks of memory during anonymous page faults. - Matthew Wilcox has also contributed some cleanup and maintenance work against eh buffer_head code int he series 'More buffer_head cleanups'. - Suren Baghdasaryan has done work on Andrea Arcangeli's series 'userfaultfd move option'. UFFDIO_MOVE permits userspace heap compaction algorithms to move userspace's pages around rather than UFFDIO_COPY'a alloc/copy/free. - Stefan Roesch has developed a 'KSM Advisor', in the series 'mm/ksm: Add ksm advisor'. This is a governor which tunes KSM's scanning aggressiveness in response to userspace's current needs. - Chengming Zhou has optimized zswap's temporary working memory use in the series 'mm/zswap: dstmem reuse optimizations and cleanups'. - Matthew Wilcox has performed some maintenance work on the writeback code, both code and within filesystems. The series is 'Clean up the writeback paths'. - Andrey Konovalov has optimized KASAN's handling of alloc and free stack traces for secondary-level allocators, in the series 'kasan: save mempool stack traces'. - Andrey also performed some KASAN maintenance work in the series 'kasan: assorted clean-ups'. - David Hildenbrand has gone to town on the rmap code. Cleanups, more pte batching, folio conversions and more. See the series 'mm/rmap: interface overhaul'. - Kinsey Ho has contributed some maintenance work on the MGLRU code in the series 'mm/mglru: Kconfig cleanup'. - Matthew Wilcox has contributed lruvec page accounting code cleanups in the series 'Remove some lruvec page accounting functions'" * tag 'mm-stable-2024-01-08-15-31' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (361 commits) mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER mm, treewide: introduce NR_PAGE_ORDERS selftests/mm: add separate UFFDIO_MOVE test for PMD splitting selftests/mm: skip test if application doesn't has root privileges selftests/mm: conform test to TAP format output selftests: mm: hugepage-mmap: conform to TAP format output selftests/mm: gup_test: conform test to TAP format output mm/selftests: hugepage-mremap: conform test to TAP format output mm/vmstat: move pgdemote_* out of CONFIG_NUMA_BALANCING mm: zsmalloc: return -ENOSPC rather than -EINVAL in zs_malloc while size is too large mm/memcontrol: remove __mod_lruvec_page_state() mm/khugepaged: use a folio more in collapse_file() slub: use a folio in __kmalloc_large_node slub: use folio APIs in free_large_kmalloc() slub: use alloc_pages_node() in alloc_slab_page() mm: remove inc/dec lruvec page state functions mm: ratelimit stat flush from workingset shrinker kasan: stop leaking stack trace handles mm/mglru: remove CONFIG_TRANSPARENT_HUGEPAGE mm/mglru: add dummy pmd_dirty() ...

kasan: stop leaking stack trace handles

2024-01-05T18:17:45+00:00

Commit 773688a6cb24 ("kasan: use stack_depot_put for Generic mode") added support for stack trace eviction for Generic KASAN. However, that commit didn't evict stack traces when the object is not put into quarantine. As a result, some stack traces are never evicted from the stack depot. In addition, with the "kasan: save mempool stack traces" series, the free stack traces for mempool objects are also not properly evicted from the stack depot. Fix both issues by: 1. Evicting all stack traces when an object if freed if it was not put into quarantine; 2. Always evicting an existing free stack trace when a new one is saved. Also do a few related clean-ups: - Do not zero out free track when initializing/invalidating free meta: set a value in shadow memory instead; - Rename KASAN_SLAB_FREETRACK to KASAN_SLAB_FREE_META; - Drop the kasan_init_cache_meta function as it's not used by KASAN; - Add comments for the kasan_alloc_meta and kasan_free_meta structs. [akpm@linux-foundation.org: make release_free_meta() and release_alloc_meta() static] Link: https://lkml.kernel.org/r/20231226225121.235865-1-andrey.konovalov@linux.dev Fixes: 773688a6cb24 ("kasan: use stack_depot_put for Generic mode") Signed-off-by: Andrey Konovalov Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Marco Elver Signed-off-by: Andrew Morton

kasan: memset free track in qlink_free

2023-12-29T19:58:42+00:00

Instead of only zeroing out the stack depot handle when evicting the free stack trace in qlink_free, zero out the whole track. Do this just to produce a similar effect for alloc and free meta. The other fields of the free track besides the stack trace handle are considered invalid at this point anyway, so no harm in zeroing them out. Link: https://lkml.kernel.org/r/db987c1cd011547e85353b0b9997de190c97e3e6.1703020707.git.andreyknvl@google.com Fixes: 773688a6cb24 ("kasan: use stack_depot_put for Generic mode") Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Tetsuo Handa Cc: Vlastimil Babka Signed-off-by: Andrew Morton

kasan: use stack_depot_put for Generic mode

2023-12-11T00:51:48+00:00

Evict alloc/free stack traces from the stack depot for Generic KASAN once they are evicted from the quaratine. For auxiliary stack traces, evict the oldest stack trace once a new one is saved (KASAN only keeps references to the last two). Also evict all saved stack traces on krealloc. To avoid double-evicting and mis-evicting stack traces (in case KASAN's metadata was corrupted), reset KASAN's per-object metadata that stores stack depot handles when the object is initialized and when it's evicted from the quarantine. Note that stack_depot_put is no-op if the handle is 0. Link: https://lkml.kernel.org/r/5cef104d9b842899489b4054fe8d1339a71acee0.1700502145.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Oscar Salvador Cc: Vlastimil Babka Signed-off-by: Andrew Morton

KASAN: remove code paths guarded by CONFIG_SLAB

2023-12-05T10:17:51+00:00

With SLAB removed and SLUB the only remaining allocator, we can clean up some code that was depending on the choice. Reviewed-by: Kees Cook Reviewed-by: Marco Elver Reviewed-by: Andrey Konovalov Acked-by: David Rientjes Tested-by: David Rientjes Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Signed-off-by: Vlastimil Babka

kasan: unify printk prefixes

2023-10-18T21:34:15+00:00

Unify prefixes for printk messages in mm/kasan/. Link: https://lkml.kernel.org/r/35589629806cf0840e5f01ec9d8011a7bad648df.1696605143.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Dmitry Vyukov Cc: kernel test robot Signed-off-by: Andrew Morton

kasan: fix lockdep report invalid wait context

2023-04-21T21:51:59+00:00

For kernels built with the following options and booting CONFIG_SLUB=y CONFIG_DEBUG_LOCKDEP=y CONFIG_PROVE_LOCKING=y CONFIG_PROVE_RAW_LOCK_NESTING=y [ 0.523115] [ BUG: Invalid wait context ] [ 0.523315] 6.3.0-rc1-yocto-standard+ #739 Not tainted [ 0.523649] ----------------------------- [ 0.523663] swapper/0/0 is trying to lock: [ 0.523663] ffff888035611360 (&c->lock){....}-{3:3}, at: put_cpu_partial+0x2e/0x1e0 [ 0.523663] other info that might help us debug this: [ 0.523663] context-{2:2} [ 0.523663] no locks held by swapper/0/0. [ 0.523663] stack backtrace: [ 0.523663] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.3.0-rc1-yocto-standard+ #739 [ 0.523663] Call Trace: [ 0.523663] [ 0.523663] dump_stack_lvl+0x64/0xb0 [ 0.523663] dump_stack+0x10/0x20 [ 0.523663] __lock_acquire+0x6c4/0x3c10 [ 0.523663] lock_acquire+0x188/0x460 [ 0.523663] put_cpu_partial+0x5a/0x1e0 [ 0.523663] __slab_free+0x39a/0x520 [ 0.523663] ___cache_free+0xa9/0xc0 [ 0.523663] qlist_free_all+0x7a/0x160 [ 0.523663] per_cpu_remove_cache+0x5c/0x70 [ 0.523663] __flush_smp_call_function_queue+0xfc/0x330 [ 0.523663] generic_smp_call_function_single_interrupt+0x13/0x20 [ 0.523663] __sysvec_call_function+0x86/0x2e0 [ 0.523663] sysvec_call_function+0x73/0x90 [ 0.523663] [ 0.523663] [ 0.523663] asm_sysvec_call_function+0x1b/0x20 [ 0.523663] RIP: 0010:default_idle+0x13/0x20 [ 0.523663] RSP: 0000:ffffffff83e07dc0 EFLAGS: 00000246 [ 0.523663] RAX: 0000000000000000 RBX: ffffffff83e1e200 RCX: ffffffff82a83293 [ 0.523663] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8119a6b1 [ 0.523663] RBP: ffffffff83e07dc8 R08: 0000000000000001 R09: ffffed1006ac0d66 [ 0.523663] R10: ffff888035606b2b R11: ffffed1006ac0d65 R12: 0000000000000000 [ 0.523663] R13: ffffffff83e1e200 R14: ffffffff84a7d980 R15: 0000000000000000 [ 0.523663] default_idle_call+0x6c/0xa0 [ 0.523663] do_idle+0x2e1/0x330 [ 0.523663] cpu_startup_entry+0x20/0x30 [ 0.523663] rest_init+0x152/0x240 [ 0.523663] arch_call_rest_init+0x13/0x40 [ 0.523663] start_kernel+0x331/0x470 [ 0.523663] x86_64_start_reservations+0x18/0x40 [ 0.523663] x86_64_start_kernel+0xbb/0x120 [ 0.523663] secondary_startup_64_no_verify+0xe0/0xeb [ 0.523663] The local_lock_irqsave() is invoked in put_cpu_partial() and happens in IPI context, due to the CONFIG_PROVE_RAW_LOCK_NESTING=y (the LD_WAIT_CONFIG not equal to LD_WAIT_SPIN), so acquire local_lock in IPI context will trigger above calltrace. This commit therefore moves qlist_free_all() from hard-irq context to task context. Link: https://lkml.kernel.org/r/20230327120019.1027640-1-qiang1.zhang@intel.com Signed-off-by: Zqiang Acked-by: Marco Elver Cc: Alexander Potapenko Cc: Andrey Konovalov Cc: Andrey Ryabinin Cc: Dmitry Vyukov Signed-off-by: Andrew Morton