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authorJohannes Weiner <jweiner@redhat.com>2011-08-25 15:59:07 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-08-25 16:25:33 -0700
commit5af12d0efdbd9967cc71a0a10c4025c4255a6254 (patch)
treee5e036671dc7ae02bebaf201126d6c19104e02d1 /mm
parenta801876638c5ce650223476c4eb8f37cea32dc1c (diff)
downloadlinux-linaro-precise-5af12d0efdbd9967cc71a0a10c4025c4255a6254.tar.gz
memcg: pin execution to current cpu while draining stock
Commit d1a05b6973c7 ("memcg do not try to drain per-cpu caches without pages") added a drain_local_stock() call to a preemptible section. The draining task looks up the cpu-local stock twice to set the draining-flag, then to drain the stock and clear the flag again. If the task is migrated to a different CPU in between, noone will clear the flag on the first stock and it will be forever undrainable. Its charge can not be recovered and the cgroup can not be deleted anymore. Properly pin the task to the executing CPU while draining stocks. Signed-off-by: Johannes Weiner <jweiner@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com Acked-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/memcontrol.c9
1 files changed, 2 insertions, 7 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 930de943727..0e40f020573 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2169,13 +2169,7 @@ static void drain_all_stock(struct mem_cgroup *root_mem, bool sync)
/* Notify other cpus that system-wide "drain" is running */
get_online_cpus();
- /*
- * Get a hint for avoiding draining charges on the current cpu,
- * which must be exhausted by our charging. It is not required that
- * this be a precise check, so we use raw_smp_processor_id() instead of
- * getcpu()/putcpu().
- */
- curcpu = raw_smp_processor_id();
+ curcpu = get_cpu();
for_each_online_cpu(cpu) {
struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
struct mem_cgroup *mem;
@@ -2192,6 +2186,7 @@ static void drain_all_stock(struct mem_cgroup *root_mem, bool sync)
schedule_work_on(cpu, &stock->work);
}
}
+ put_cpu();
if (!sync)
goto out;