2017-06-01 18:36:39

by Roman Gushchin

Subject: [RFC PATCH v2 4/7] mm, oom: introduce oom_kill_all_tasks option for memory cgroups

This option defines whether a cgroup should be treated
as a single entity by the OOM killer.

If set, the OOM killer will compare the whole cgroup with other
memory consumers (other cgroups and tasks in the root cgroup),
and in case of an OOM will kill all belonging tasks.

Disabled by default.

Signed-off-by: Roman Gushchin <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Li Zefan <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Vladimir Davydov <[email protected]>
Cc: Tetsuo Handa <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
include/linux/memcontrol.h | 3 +++
mm/memcontrol.c | 33 +++++++++++++++++++++++++++++++++
2 files changed, 36 insertions(+)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 899949b..8a308c9 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -195,6 +195,9 @@ struct mem_cgroup {
/* OOM-Killer disable */
int oom_kill_disable;

+ /* kill all tasks below in case of OOM */
+ bool oom_kill_all_tasks;
+
/* handle for "memory.events" */
struct cgroup_file events_file;

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c131f7e..d4ffa79 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5156,6 +5156,33 @@ static ssize_t memory_max_write(struct kernfs_open_file *of,
return nbytes;
}

+static int memory_oom_kill_all_tasks_show(struct seq_file *m, void *v)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+ bool oom_kill_all_tasks = memcg->oom_kill_all_tasks;
+
+ seq_printf(m, "%d\n", oom_kill_all_tasks);
+
+ return 0;
+}
+
+static ssize_t memory_oom_kill_all_tasks_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes,
+ loff_t off)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+ int oom_kill_all_tasks;
+ int err;
+
+ err = kstrtoint(strstrip(buf), 0, &oom_kill_all_tasks);
+ if (err)
+ return err;
+
+ memcg->oom_kill_all_tasks = !!oom_kill_all_tasks;
+
+ return nbytes;
+}
+
static int memory_events_show(struct seq_file *m, void *v)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
@@ -5265,6 +5292,12 @@ static struct cftype memory_files[] = {
.write = memory_max_write,
},
{
+ .name = "oom_kill_all_tasks",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = memory_oom_kill_all_tasks_show,
+ .write = memory_oom_kill_all_tasks_write,
+ },
+ {
.name = "events",
.flags = CFTYPE_NOT_ON_ROOT,
.file_offset = offsetof(struct mem_cgroup, events_file),
--
2.7.4

2017-06-04 19:30:15

by Vladimir Davydov

Subject: Re: [RFC PATCH v2 4/7] mm, oom: introduce oom_kill_all_tasks option for memory cgroups

On Thu, Jun 01, 2017 at 07:35:12PM +0100, Roman Gushchin wrote:
> This option defines whether a cgroup should be treated
> as a single entity by the OOM killer.
>
> If set, the OOM killer will compare the whole cgroup with other
> memory consumers (other cgroups and tasks in the root cgroup),
> and in case of an OOM will kill all belonging tasks.
>
> Disabled by default.
>
...
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> @@ -5265,6 +5292,12 @@ static struct cftype memory_files[] = {
> .write = memory_max_write,
> },
> {
> + .name = "oom_kill_all_tasks",
> + .flags = CFTYPE_NOT_ON_ROOT,
> + .seq_show = memory_oom_kill_all_tasks_show,
> + .write = memory_oom_kill_all_tasks_write,
> + },
> + {
> .name = "events",
> .flags = CFTYPE_NOT_ON_ROOT,
> .file_offset = offsetof(struct mem_cgroup, events_file),

I don't really like the name of the new knob, but can't come up with
anything better :-( May be, drop '_tasks' suffix and call it just
'oom_kill_all'? Or perhaps we should emphasize the fact that this
cgroup is treated as a single entity by the OOM killer by calling it
'oom_entity' or 'oom_unit'? Dunno...