Potentially, here can be last css refcnt, so we should have stable memory to access parent pointer.
Signed-off-by: Kirill Tkhai <[email protected]> --- mm/memcontrol.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 797cb8e6df6d..e82c59f6a984 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3525,7 +3525,13 @@ void memcg_uncharge_kmem(struct mem_cgroup *memcg, * * The memory barrier imposed by test&clear is paired with the * explicit one in memcg_kmem_mark_dead(). + * + * We take RCU to remain memcg memory stable for parent dereferencing. + * Parent's memory is stable even in case of page_counter_uncharge() + * has decremented its last charged memory, because child dentry owns + * parents's dentry refcnt. */ + rcu_read_lock(); if (memcg_kmem_test_and_clear_dead(memcg)) css_put(&memcg->css); @@ -3541,6 +3547,7 @@ 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) _______________________________________________ Devel mailing list [email protected] https://lists.openvz.org/mailman/listinfo/devel
