Commit b6bf9abb authored by Dan Schatzberg's avatar Dan Schatzberg Committed by Linus Torvalds

mm/memcg: add oom_group_kill memory event

Our container agent wants to know when a container exits if it was OOM
killed or not to report to the user.  We use memory.oom.group = 1 to
ensure that OOM kills within the container's cgroup kill everything.
Existing memory.events are insufficient for knowing if this triggered:

1) Our current approach reads memory.events oom_kill and reports the
   container was killed if the value is non-zero. This is erroneous in
   some cases where containers create their children cgroups with
   memory.oom.group=1 as such OOM kills will get counted against the
   container cgroup's oom_kill counter despite not actually OOM killing
   the entire container.

2) Reading memory.events.local will fail to identify OOM kills in leaf
   cgroups (that don't set memory.oom.group) within the container
   cgroup.

This patch adds a new oom_group_kill event when memory.oom.group
triggers to allow userspace to cleanly identify when an entire cgroup is
oom killed.

[schatzberg.dan@gmail.com: changes from Johannes and Chris]
  Link: https://lkml.kernel.org/r/20211213162511.2492267-1-schatzberg.dan@gmail.com

Link: https://lkml.kernel.org/r/20211203162426.3375036-1-schatzberg.dan@gmail.comSigned-off-by: default avatarDan Schatzberg <schatzberg.dan@gmail.com>
Reviewed-by: default avatarRoman Gushchin <guro@fb.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarChris Down <chris@chrisdown.name>
Reviewed-by: default avatarShakeel Butt <shakeelb@google.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan.x@bytedance.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 46a53371
...@@ -1268,6 +1268,9 @@ PAGE_SIZE multiple when read back. ...@@ -1268,6 +1268,9 @@ PAGE_SIZE multiple when read back.
The number of processes belonging to this cgroup The number of processes belonging to this cgroup
killed by any kind of OOM killer. killed by any kind of OOM killer.
oom_group_kill
The number of times a group OOM has occurred.
memory.events.local memory.events.local
Similar to memory.events but the fields in the file are local Similar to memory.events but the fields in the file are local
to the cgroup i.e. not hierarchical. The file modified event to the cgroup i.e. not hierarchical. The file modified event
......
...@@ -42,6 +42,7 @@ enum memcg_memory_event { ...@@ -42,6 +42,7 @@ enum memcg_memory_event {
MEMCG_MAX, MEMCG_MAX,
MEMCG_OOM, MEMCG_OOM,
MEMCG_OOM_KILL, MEMCG_OOM_KILL,
MEMCG_OOM_GROUP_KILL,
MEMCG_SWAP_HIGH, MEMCG_SWAP_HIGH,
MEMCG_SWAP_MAX, MEMCG_SWAP_MAX,
MEMCG_SWAP_FAIL, MEMCG_SWAP_FAIL,
......
...@@ -6318,6 +6318,8 @@ static void __memory_events_show(struct seq_file *m, atomic_long_t *events) ...@@ -6318,6 +6318,8 @@ static void __memory_events_show(struct seq_file *m, atomic_long_t *events)
seq_printf(m, "oom %lu\n", atomic_long_read(&events[MEMCG_OOM])); seq_printf(m, "oom %lu\n", atomic_long_read(&events[MEMCG_OOM]));
seq_printf(m, "oom_kill %lu\n", seq_printf(m, "oom_kill %lu\n",
atomic_long_read(&events[MEMCG_OOM_KILL])); atomic_long_read(&events[MEMCG_OOM_KILL]));
seq_printf(m, "oom_group_kill %lu\n",
atomic_long_read(&events[MEMCG_OOM_GROUP_KILL]));
} }
static int memory_events_show(struct seq_file *m, void *v) static int memory_events_show(struct seq_file *m, void *v)
......
...@@ -994,6 +994,7 @@ static void oom_kill_process(struct oom_control *oc, const char *message) ...@@ -994,6 +994,7 @@ static void oom_kill_process(struct oom_control *oc, const char *message)
* If necessary, kill all tasks in the selected memory cgroup. * If necessary, kill all tasks in the selected memory cgroup.
*/ */
if (oom_group) { if (oom_group) {
memcg_memory_event(oom_group, MEMCG_OOM_GROUP_KILL);
mem_cgroup_print_oom_group(oom_group); mem_cgroup_print_oom_group(oom_group);
mem_cgroup_scan_tasks(oom_group, oom_kill_memcg_member, mem_cgroup_scan_tasks(oom_group, oom_kill_memcg_member,
(void *)message); (void *)message);
......
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