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authorYang Shi <yang.shi@linux.alibaba.com>2019-08-02 21:48:44 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-08-03 07:02:00 -0700
commitfa1e512fac717f34e7c12d7a384c46e90a647392 (patch)
treebe1f6e39f770aaeb27c6eb68e3e0d2ed2650a111 /mm/vmscan.c
parent7bc36e3ce91471b6377c8eadc0a2f220a2280083 (diff)
mm: vmscan: check if mem cgroup is disabled or not before calling memcg slab shrinker
Shakeel Butt reported premature oom on kernel with "cgroup_disable=memory" since mem_cgroup_is_root() returns false even though memcg is actually NULL. The drop_caches is also broken. It is because commit aeed1d325d42 ("mm/vmscan.c: generalize shrink_slab() calls in shrink_node()") removed the !memcg check before !mem_cgroup_is_root(). And, surprisingly root memcg is allocated even though memory cgroup is disabled by kernel boot parameter. Add mem_cgroup_disabled() check to make reclaimer work as expected. Link: http://lkml.kernel.org/r/1563385526-20805-1-git-send-email-yang.shi@linux.alibaba.com Fixes: aeed1d325d42 ("mm/vmscan.c: generalize shrink_slab() calls in shrink_node()") Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Reported-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Jan Hadrava <had@kam.mff.cuni.cz> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Roman Gushchin <guro@fb.com> Cc: Hugh Dickins <hughd@google.com> Cc: Qian Cai <cai@lca.pw> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: <stable@vger.kernel.org> [4.19+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmscan.c')
-rw-r--r--mm/vmscan.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 44df66a98f2a..dbdc46a84f63 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -699,7 +699,14 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
unsigned long ret, freed = 0;
struct shrinker *shrinker;
- if (!mem_cgroup_is_root(memcg))
+ /*
+ * The root memcg might be allocated even though memcg is disabled
+ * via "cgroup_disable=memory" boot parameter. This could make
+ * mem_cgroup_is_root() return false, then just run memcg slab
+ * shrink, but skip global shrink. This may result in premature
+ * oom.
+ */
+ if (!mem_cgroup_disabled() && !mem_cgroup_is_root(memcg))
return shrink_slab_memcg(gfp_mask, nid, memcg, priority);
if (!down_read_trylock(&shrinker_rwsem))