[PATCH] memcg: do not call reclaim if !__GFP_WAIT

[Vladimir Davydov]

When trimming memcg consumption excess (see memory.high), we call
try_to_free_mem_cgroup_pages without checking if we are allowed to sleep
in the current context, which can result in a deadlock. Fix this.

Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
---
 mm/memcontrol.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 14c2f2017e37..9da23a7ec4c0 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2323,6 +2323,8 @@ done_restock:
 	css_get_many(&memcg->css, batch);
 	if (batch > nr_pages)
 		refill_stock(memcg, batch - nr_pages);
+	if (!(gfp_mask & __GFP_WAIT))
+		goto done;
 	/*
 	 * If the hierarchy is above the normal consumption range,
 	 * make the charging task trim their excess contribution.
-- 
2.1.4

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