From def0fdae813dbbbbb588bfc5f52856be2e842b35 Mon Sep 17 00:00:00 2001
From: Johannes Weiner <hannes@cmpxchg.org>
Date: Tue, 14 May 2019 15:47:15 -0700
Subject: [PATCH] mm: memcontrol: fix NUMA round-robin reclaim at intermediate
level
When a cgroup is reclaimed on behalf of a configured limit, reclaim
needs to round-robin through all NUMA nodes that hold pages of the memcg
in question. However, when assembling the mask of candidate NUMA nodes,
the code only consults the *local* cgroup LRU counters, not the
recursive counters for the entire subtree. Cgroup limits are frequently
configured against intermediate cgroups that do not have memory on their
own LRUs. In this case, the node mask will always come up empty and
reclaim falls back to scanning only the current node.
If a cgroup subtree has some memory on one node but the processes are
bound to another node afterwards, the limit reclaim will never age or
reclaim that memory anymore.
To fix this, use the recursive LRU counts for a cgroup subtree to
determine which nodes hold memory of that cgroup.
The code has been broken like this forever, so it doesn't seem to be a
problem in practice. I just noticed it while reviewing the way the LRU
counters are used in general.
Link: http://lkml.kernel.org/r/20190412151507.2769-5-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/memcontrol.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 7a764cbf84952..e50a2db5b4ff0 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1507,13 +1507,13 @@ static bool test_mem_cgroup_node_reclaimable(struct mem_cgroup *memcg,
{
struct lruvec *lruvec = mem_cgroup_lruvec(NODE_DATA(nid), memcg);
- if (lruvec_page_state_local(lruvec, NR_INACTIVE_FILE) ||
- lruvec_page_state_local(lruvec, NR_ACTIVE_FILE))
+ if (lruvec_page_state(lruvec, NR_INACTIVE_FILE) ||
+ lruvec_page_state(lruvec, NR_ACTIVE_FILE))
return true;
if (noswap || !total_swap_pages)
return false;
- if (lruvec_page_state_local(lruvec, NR_INACTIVE_ANON) ||
- lruvec_page_state_local(lruvec, NR_ACTIVE_ANON))
+ if (lruvec_page_state(lruvec, NR_INACTIVE_ANON) ||
+ lruvec_page_state(lruvec, NR_ACTIVE_ANON))
return true;
return false;
--
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