The patch titled
memcg: pin execution to current cpu while draining stock
has been added to the -mm tree. Its filename is
memcg-pin-execution-to-current-cpu-while-draining-stock.patch
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------------------------------------------------------
Subject: memcg: pin execution to current cpu while draining stock
From: Johannes Weiner <jweiner@xxxxxxxxxx>
Commit d1a05b6 ("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@xxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: <stable@xxxxxxxxxx> [3.0.x]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)
diff -puN mm/memcontrol.c~memcg-pin-execution-to-current-cpu-while-draining-stock mm/memcontrol.c
--- a/mm/memcontrol.c~memcg-pin-execution-to-current-cpu-while-draining-stock
+++ a/mm/memcontrol.c
@@ -2169,13 +2169,7 @@ static void drain_all_stock(struct mem_c
/* 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_c
schedule_work_on(cpu, &stock->work);
}
}
+ put_cpu();
if (!sync)
goto out;
_
Patches currently in -mm which might be from jweiner@xxxxxxxxxx are
memcg-pin-execution-to-current-cpu-while-draining-stock.patch
linux-next.patch
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