lkml.org 
[lkml]   [2016]   [Oct]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] mm/slab: fix kmemcg cache creation delayed issue
Date
From: Joonsoo Kim <iamjoonsoo.kim@lge.com>

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 quitely.
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")
Cc: stable@vger.kernel.org
Reported-by: Doug Smythies <dsmythies@telus.net>
Tested-by: Doug Smythies <dsmythies@telus.net>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
---
mm/slab.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/slab.c b/mm/slab.c
index 6508b4d..3c83c29 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -961,7 +961,7 @@ 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:
--
1.9.1
\
 
 \ /
  Last update: 2016-10-06 08:21    [W:0.045 / U:0.128 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site