[rh7] mm: Add RCU read brackets into memcg_uncharge_kmem()

Submitted by Kirill Tkhai on May 7, 2020, 9:18 a.m.

Details

Message ID 158884312287.22459.13062185125232574472.stgit@localhost.localdomain
State New
Series "mm: Move memcg_uncharge_kmem() to bottom of __memcg_uncharge_slab()"
Headers show

Commit Message

Kirill Tkhai May 7, 2020, 9:18 a.m.
Potentially, here can be last css refcnt, so we should
have stable memory to access parent pointer.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
---
 mm/memcontrol.c |    2 ++
 1 file changed, 2 insertions(+)

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diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 797cb8e6df6d..d83908598ad1 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3518,6 +3518,7 @@  void memcg_uncharge_kmem(struct mem_cgroup *memcg,
 	if (kmem)
 		return;
 
+	rcu_read_lock();
 	/*
 	 * Releases a reference taken in memcg_deactivate_kmem in case
 	 * this last uncharge is racing with the offlining code or it is
@@ -3541,6 +3542,7 @@  void memcg_uncharge_kmem(struct mem_cgroup *memcg,
 		else
 			break;
 	}
+	rcu_read_unlock();
 }
 
 int __memcg_charge_slab(struct kmem_cache *s, gfp_t gfp, unsigned int nr_pages)