The patch titled Subject: slub: kmem_cache_shrink: fix crash due to uninitialized discard list has been removed from the -mm tree. Its filename was slub-never-fail-to-shrink-cache-init-discard-list-after-freeing-slabs.patch This patch was dropped because it was folded into slub-never-fail-to-shrink-cache.patch ------------------------------------------------------ From: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> Subject: slub: kmem_cache_shrink: fix crash due to uninitialized discard list Currently, the discard list is only initialized at the beginning of the function. As a result, if there are > 1 nodes, we can get use-after-free while processing the second or higher node: WARNING: CPU: 60 PID: 1 at lib/list_debug.c:29 __list_add+0x3c/0xa9() list_add corruption. next->prev should be prev (ffff881ff0a6bb98), but was ffffea007ff57020. (next=ffffea007fbf7320). Modules linked in: CPU: 60 PID: 1 Comm: swapper/0 Not tainted 3.19.0-rc7-next-20150203-gb50cadf #2178 Hardware name: Intel Corporation BRICKLAND/BRICKLAND, BIOS BIVTSDP1.86B.0038.R02.1307231126 07/23/2013 0000000000000009 ffff881ff0a6ba88 ffffffff81c2e096 ffffffff810e2d03 ffff881ff0a6bad8 ffff881ff0a6bac8 ffffffff8108b320 ffff881ff0a6bb18 ffffffff8154bbc7 ffff881ff0a6bb98 ffffea007fbf7320 ffffea00ffc3c220 Call Trace: [<ffffffff81c2e096>] dump_stack+0x4c/0x65 [<ffffffff810e2d03>] ? console_unlock+0x398/0x3c7 [<ffffffff8108b320>] warn_slowpath_common+0xa1/0xbb [<ffffffff8154bbc7>] ? __list_add+0x3c/0xa9 [<ffffffff8108b380>] warn_slowpath_fmt+0x46/0x48 [<ffffffff8154bbc7>] __list_add+0x3c/0xa9 [<ffffffff811bf5aa>] __kmem_cache_shrink+0x12b/0x24c [<ffffffff81190ca9>] kmem_cache_shrink+0x26/0x38 [<ffffffff815848b4>] acpi_os_purge_cache+0xe/0x12 [<ffffffff815c6424>] acpi_purge_cached_objects+0x32/0x7a [<ffffffff825f70f1>] acpi_initialize_objects+0x17e/0x1ae [<ffffffff825f5177>] ? acpi_sleep_proc_init+0x2a/0x2a [<ffffffff825f5209>] acpi_init+0x92/0x25e [<ffffffff810002bd>] ? do_one_initcall+0x90/0x17f [<ffffffff811bdfcd>] ? kfree+0x1fc/0x2d5 [<ffffffff825f5177>] ? acpi_sleep_proc_init+0x2a/0x2a [<ffffffff8100031a>] do_one_initcall+0xed/0x17f [<ffffffff825ae0e2>] kernel_init_freeable+0x1f0/0x278 [<ffffffff81c1f31a>] ? rest_init+0x13e/0x13e [<ffffffff81c1f328>] kernel_init+0xe/0xda [<ffffffff81c3ca7c>] ret_from_fork+0x7c/0xb0 [<ffffffff81c1f31a>] ? rest_init+0x13e/0x13e Fix this by initializing the discard list at each iteration of the for_each_kmem_cache_node loop. Also, move promote lists initialization to the beginning of the loop to conform. fixes: slub-never-fail-to-shrink-cache Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> Reported-by: Huang Ying <ying.huang@xxxxxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: Pekka Enberg <penberg@xxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/slub.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff -puN mm/slub.c~slub-never-fail-to-shrink-cache-init-discard-list-after-freeing-slabs mm/slub.c --- a/mm/slub.c~slub-never-fail-to-shrink-cache-init-discard-list-after-freeing-slabs +++ a/mm/slub.c @@ -3376,18 +3376,19 @@ int __kmem_cache_shrink(struct kmem_cach struct kmem_cache_node *n; struct page *page; struct page *t; - LIST_HEAD(discard); + struct list_head discard; struct list_head promote[SHRINK_PROMOTE_MAX]; unsigned long flags; - for (i = 0; i < SHRINK_PROMOTE_MAX; i++) - INIT_LIST_HEAD(promote + i); - flush_all(s); for_each_kmem_cache_node(s, node, n) { if (!n->nr_partial) continue; + INIT_LIST_HEAD(&discard); + for (i = 0; i < SHRINK_PROMOTE_MAX; i++) + INIT_LIST_HEAD(promote + i); + spin_lock_irqsave(&n->list_lock, flags); /* @@ -3417,7 +3418,7 @@ int __kmem_cache_shrink(struct kmem_cach * partial list. */ for (i = SHRINK_PROMOTE_MAX - 1; i >= 0; i--) - list_splice_init(promote + i, &n->partial); + list_splice(promote + i, &n->partial); spin_unlock_irqrestore(&n->list_lock, flags); _ Patches currently in -mm which might be from vdavydov@xxxxxxxxxxxxx are origin.patch list_lru-introduce-list_lru_shrink_countwalk.patch fs-consolidate-nrfree_cached_objects-args-in-shrink_control.patch vmscan-per-memory-cgroup-slab-shrinkers.patch memcg-rename-some-cache-id-related-variables.patch memcg-add-rwsem-to-synchronize-against-memcg_caches-arrays-relocation.patch list_lru-get-rid-of-active_nodes.patch list_lru-organize-all-list_lrus-to-list.patch list_lru-introduce-per-memcg-lists.patch fs-make-shrinker-memcg-aware.patch fs-shrinker-always-scan-at-least-one-object-of-each-type.patch slab-embed-memcg_cache_params-to-kmem_cache.patch slab-link-memcg-caches-of-the-same-kind-into-a-list.patch cgroup-release-css-id-after-css_free.patch slab-use-css-id-for-naming-per-memcg-caches.patch memcg-free-memcg_caches-slot-on-css-offline.patch list_lru-add-helpers-to-isolate-items.patch memcg-reparent-list_lrus-and-free-kmemcg_id-on-css-offline.patch slub-never-fail-to-shrink-cache.patch slub-fix-kmem_cache_shrink-return-value.patch slub-make-dead-caches-discard-free-slabs-immediately.patch memcg-cleanup-static-keys-decrement.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html