The patch titled
Subject: slub: kmem_cache_shrink: check if partial list is empty under list_lock
has been removed from the -mm tree. Its filename was
slub-kmem_cache_shrink-check-if-partial-list-is-empty-under-list_lock.patch
This patch was dropped because it was withdrawn
------------------------------------------------------
From: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Subject: slub: kmem_cache_shrink: check if partial list is empty under list_lock
SLUB's implementation of kmem_cache_shrink skips nodes that have
nr_partial=0, because they surely don't have any empty slabs to free.
This check is done w/o holding any locks, therefore it can race with
concurrent kfree adding an empty slab to a partial list. As a result, a
just shrinked cache can have empty slabs.
This is unacceptable for kmemcg, which needs to be sure that there will be
no empty slabs on dead memcg caches after kmem_cache_shrink was called,
because otherwise we may leak a dead cache.
Let's fix this race by checking if node partial list is empty under
node->list_lock. Since the nr_partial!=0 branch of kmem_cache_shrink does
nothing if the list is empty, we can simply remove the nr_partial=0 check.
Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Reported-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slub.c | 3 ---
1 file changed, 3 deletions(-)
diff -puN mm/slub.c~slub-kmem_cache_shrink-check-if-partial-list-is-empty-under-list_lock mm/slub.c
--- a/mm/slub.c~slub-kmem_cache_shrink-check-if-partial-list-is-empty-under-list_lock
+++ a/mm/slub.c
@@ -3395,9 +3395,6 @@ int __kmem_cache_shrink(struct kmem_cach
flush_all(s);
for_each_kmem_cache_node(s, node, n) {
- if (!n->nr_partial)
- continue;
-
for (i = 0; i < objects; i++)
INIT_LIST_HEAD(slabs_by_inuse + i);
_
Patches currently in -mm which might be from vdavydov@xxxxxxxxxxxxx are
mm-slabh-wrap-the-whole-file-with-guarding-macro.patch
memcg-cleanup-memcg_cache_params-refcnt-usage.patch
memcg-destroy-kmem-caches-when-last-slab-is-freed.patch
memcg-mark-caches-that-belong-to-offline-memcgs-as-dead.patch
slub-dont-fail-kmem_cache_shrink-if-slab-placement-optimization-fails.patch
slub-make-slab_free-non-preemptable.patch
memcg-wait-for-kfrees-to-finish-before-destroying-cache.patch
slub-make-dead-memcg-caches-discard-free-slabs-immediately.patch
slab-do-not-keep-free-objects-slabs-on-dead-memcg-caches.patch
slab-set-free_limit-for-dead-caches-to-0.patch
mm-memcontrol-fold-mem_cgroup_do_charge.patch
mm-memcontrol-rearrange-charging-fast-path.patch
mm-memcontrol-reclaim-at-least-once-for-__gfp_noretry.patch
mm-huge_memory-use-gfp_transhuge-when-charging-huge-pages.patch
mm-memcontrol-retry-reclaim-for-oom-disabled-and-__gfp_nofail-charges.patch
mm-memcontrol-remove-explicit-oom-parameter-in-charge-path.patch
mm-memcontrol-simplify-move-precharge-function.patch
mm-memcontrol-catch-root-bypass-in-move-precharge.patch
mm-memcontrol-use-root_mem_cgroup-res_counter.patch
mm-memcontrol-remove-ordering-between-pc-mem_cgroup-and-pagecgroupused.patch
mm-memcontrol-do-not-acquire-page_cgroup-lock-for-kmem-pages.patch
mm-memcontrol-rewrite-charge-api.patch
mm-memcontrol-rewrite-uncharge-api.patch
mm-memcontrol-rewrite-uncharge-api-fix-5.patch
mm-memcontrol-use-page-lists-for-uncharge-batching.patch
page-cgroup-trivial-cleanup.patch
page-cgroup-get-rid-of-nr_pcg_flags.patch
fork-exec-cleanup-mm-initialization.patch
fork-reset-mm-pinned_vm.patch
fork-copy-mms-vm-usage-counters-under-mmap_sem.patch
fork-make-mm_init_owner-static.patch
linux-next.patch
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