Previously on the cpu hot-unplug, the kernel would call
drain_obj_stock() with objcg local lock. However local lock was not
neede as the stock which was accessed belongs to a dead cpu but we kept
it there to disable irqs as drain_obj_stock() may call
mod_objcg_mlstate() which required irqs disabled. However there is no
need to disable irqs now for mod_objcg_mlstate(), so we can remove the
lcoal lock altogether from cpu hot-unplug path.
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
---
mm/memcontrol.c | 10 +---------
1 file changed, 1 insertion(+), 9 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index af7df675d733..539cd76e1492 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2060,16 +2060,8 @@ void drain_all_stock(struct mem_cgroup *root_memcg)
static int memcg_hotplug_cpu_dead(unsigned int cpu)
{
- struct obj_stock_pcp *obj_st;
-
- obj_st = &per_cpu(obj_stock, cpu);
-
- /* drain_obj_stock requires objstock.lock */
- local_lock(&obj_stock.lock);
- drain_obj_stock(obj_st);
- local_unlock(&obj_stock.lock);
-
/* no need for the local lock */
+ drain_obj_stock(&per_cpu(obj_stock, cpu));
drain_stock_fully(&per_cpu(memcg_stock, cpu));
return 0;
--
2.47.1