The patch titled
Subject: mm/vmscan: add a fatal signals check in drop_slab_node
has been added to the -mm tree. Its filename is
mm-vmscan-add-a-fatal-signals-check-in-drop_slab_node.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-vmscan-add-a-fatal-signals-check-in-drop_slab_node.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-vmscan-add-a-fatal-signals-check-in-drop_slab_node.patch
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------------------------------------------------------
From: Chunxin Zang <zangchunxin@xxxxxxxxxxxxx>
Subject: mm/vmscan: add a fatal signals check in drop_slab_node
On our server, there are about 10k memcg in one machine. They use memory
very frequently. We have observed that drop_caches can take a
considerable amount of time, and can't stop it.
There are two reasons:
1. There is somebody constantly generating more objects to reclaim
on drop_caches, result the 'freed' always bigger than 10.
2. The process has no chance to process signals.
We can get the following info through 'ps':
root:~# ps -aux | grep drop
root 357956 ... R Aug25 21119854:55 echo 3 > /proc/sys/vm/drop_caches
root 1771385 ... R Aug16 21146421:17 echo 3 > /proc/sys/vm/drop_caches
Add a bail out on the fatal signals in the main loop so that the
operation can be terminated by userspace.
Link: https://lkml.kernel.org/r/20200916025359.70203-1-zangchunxin@xxxxxxxxxxxxx
Signed-off-by: Chunxin Zang <zangchunxin@xxxxxxxxxxxxx>
Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Acked-by: Chris Down <chris@xxxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmscan.c | 3 +++
1 file changed, 3 insertions(+)
--- a/mm/vmscan.c~mm-vmscan-add-a-fatal-signals-check-in-drop_slab_node
+++ a/mm/vmscan.c
@@ -702,6 +702,9 @@ void drop_slab_node(int nid)
if (fatal_signal_pending(current))
return;
+ if (fatal_signal_pending(current))
+ return;
+
freed = 0;
memcg = mem_cgroup_iter(NULL, NULL, NULL);
do {
_
Patches currently in -mm which might be from zangchunxin@xxxxxxxxxxxxx are
mm-vmscan-fix-infinite-loop-in-drop_slab_node.patch
mm-vmscan-add-a-fatal-signals-check-in-drop_slab_node.patch
