From 9516a18a9a253a94292e74f11f92083126c5a237 Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Fri, 11 Dec 2015 13:40:24 -0800 Subject: [PATCH] memcg: fix memory.high target When the memory.high threshold is exceeded, try_charge() schedules a task_work to reclaim the excess. The reclaim target is set to the number of pages requested by try_charge(). This is wrong, because try_charge() usually charges more pages than requested (batch > nr_pages) in order to refill per cpu stocks. As a result, a process in a cgroup can easily exceed memory.high significantly when doing a lot of charges w/o returning to userspace (e.g. reading a file in big chunks). Fix this issue by assuring that when exceeding memory.high a process reclaims as many pages as were actually charged (i.e. batch). Signed-off-by: Vladimir Davydov Acked-by: Johannes Weiner Acked-by: Michal Hocko Cc: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index c92a65b2b4ab..32259e37a66b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2128,7 +2128,7 @@ done_restock: */ do { if (page_counter_read(&memcg->memory) > memcg->high) { - current->memcg_nr_pages_over_high += nr_pages; + current->memcg_nr_pages_over_high += batch; set_notify_resume(current); break; } -- 2.20.1