[PATCH 4/5] mm, memcg: avoid possible NULL pointer dereferencing in mem_cgroup_init()

Miaohe Lin
2021-07-29T12:57:54Z

rtpn might be NULL in very rare case. We have better to check it before
dereferencing it. Since memcg can live with NULL rb_tree_per_node in
soft_limit_tree, warn this case and continue.

Signed-off-by: Miaohe Lin <linmiaohe-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
---
mm/memcontrol.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 5b4592d1e0f2..70a32174e7c4 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -7109,6 +7109,8 @@ static int __init mem_cgroup_init(void)
rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL,
node_online(node) ? node : NUMA_NO_NODE);

+ if (WARN_ON_ONCE(!rtpn))
+ continue;
rtpn->rb_root = RB_ROOT;
rtpn->rb_rightmost = NULL;
spin_lock_init(&rtpn->lock);
--
2.23.0