Messages in this thread Patch in this message | | | From | zangchunxin@bytedanc ... | Subject | [PATCH v5] mm/vmscan: add a fatal signals check in drop_slab_node | Date | Wed, 16 Sep 2020 10:53:59 +0800 |
| |
From: Chunxin Zang <zangchunxin@bytedance.com>
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.
Signed-off-by: Chunxin Zang <zangchunxin@bytedance.com> Signed-off-by: Muchun Song <songmuchun@bytedance.com> --- changelogs in v5: 1) v4 patch used wrong branch, very apologies about that.
changelogs in v4: changelogs in v3: 1) Fix some descriptive problems pointed out by Michal Hocko. v2 named: mm/vmscan: fix infinite loop in drop_slab_node
changelogs in v2: 1) via check fatal signal break loop.
mm/vmscan.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/mm/vmscan.c b/mm/vmscan.c index b6d84326bdf2..c3ed8b45d264 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -704,6 +704,9 @@ void drop_slab_node(int nid) do { struct mem_cgroup *memcg = NULL; + if (fatal_signal_pending(current)) + return; + freed = 0; memcg = mem_cgroup_iter(NULL, NULL, NULL); do { -- 2.11.0
| |