| From 86d9f48534e800e4d62cdc1b5aaf539f4c1d47d6 Mon Sep 17 00:00:00 2001 |
| From: Joonsoo Kim <iamjoonsoo.kim@lge.com> |
| Date: Thu, 27 Oct 2016 17:46:18 -0700 |
| Subject: mm/slab: fix kmemcg cache creation delayed issue |
| |
| From: Joonsoo Kim <iamjoonsoo.kim@lge.com> |
| |
| commit 86d9f48534e800e4d62cdc1b5aaf539f4c1d47d6 upstream. |
| |
| 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> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| mm/slab.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/mm/slab.c |
| +++ b/mm/slab.c |
| @@ -964,7 +964,7 @@ static int setup_kmem_cache_node(struct |
| * 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: |
