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authorJoonsoo Kim <iamjoonsoo.kim@lge.com>2016-10-28 03:46:18 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2016-10-28 04:43:42 +0300
commit86d9f48534e800e4d62cdc1b5aaf539f4c1d47d6 (patch)
tree0be877fe7dced4128efce07c15709deac322ca68 /mm/slab.c
parent18c2152d526e7956457fcdcbdf6d77ae2c663a26 (diff)
downloadlinux-86d9f48534e800e4d62cdc1b5aaf539f4c1d47d6.tar.xz
mm/slab: fix kmemcg cache creation delayed issue
There is a bug report that SLAB makes extreme load average due to over 2000 kworker thread. https://bugzilla.kernel.org/show_bug.cgi?id=172981 This issue is caused by kmemcg feature that try to create new set of kmem_caches for each memcg. Recently, kmem_cache creation is slowed by synchronize_sched() and futher kmem_cache creation is also delayed since kmem_cache creation is synchronized by a global slab_mutex lock. So, the number of kworker that try to create kmem_cache increases quietly. synchronize_sched() is for lockless access to node's shared array but it's not needed when a new kmem_cache is created. So, this patch rules out that case. Fixes: 801faf0db894 ("mm/slab: lockless decision to grow cache") Link: http://lkml.kernel.org/r/1475734855-4837-1-git-send-email-iamjoonsoo.kim@lge.com Reported-by: Doug Smythies <dsmythies@telus.net> Tested-by: Doug Smythies <dsmythies@telus.net> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/slab.c')
-rw-r--r--mm/slab.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/slab.c b/mm/slab.c
index 090fb26b3a39..c451e3f6bbf6 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -966,7 +966,7 @@ static int setup_kmem_cache_node(struct kmem_cache *cachep,
* guaranteed to be valid until irq is re-enabled, because it will be
* freed after synchronize_sched().
*/
- if (force_change)
+ if (old_shared && force_change)
synchronize_sched();
fail: