2017-06-01 18:36:33

by Roman Gushchin

Subject: [RFC PATCH v2 5/7] mm, oom: introduce oom_score_adj for memory cgroups

Introduce a per-memory-cgroup oom_score_adj setting.
A read-write single value file which exits on non-root
cgroups. The default is "0".

It will have a similar meaning to a per-process value,
available via /proc/<pid>/oom_score_adj.
Should be in a range [-1000, 1000].

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 | 36 ++++++++++++++++++++++++++++++++++++
2 files changed, 39 insertions(+)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 8a308c9..818a42e 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -198,6 +198,9 @@ struct mem_cgroup {
/* kill all tasks below in case of OOM */
bool oom_kill_all_tasks;

+ /* OOM kill score adjustment */
+ short oom_score_adj;
+
/* handle for "memory.events" */
struct cgroup_file events_file;

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d4ffa79..f979ac7 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5183,6 +5183,36 @@ static ssize_t memory_oom_kill_all_tasks_write(struct kernfs_open_file *of,
return nbytes;
}

+static int memory_oom_score_adj_show(struct seq_file *m, void *v)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+ short oom_score_adj = memcg->oom_score_adj;
+
+ seq_printf(m, "%d\n", oom_score_adj);
+
+ return 0;
+}
+
+static ssize_t memory_oom_score_adj_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_score_adj;
+ int err;
+
+ err = kstrtoint(strstrip(buf), 0, &oom_score_adj);
+ if (err)
+ return err;
+
+ if (oom_score_adj < OOM_SCORE_ADJ_MIN ||
+ oom_score_adj > OOM_SCORE_ADJ_MAX)
+ return -EINVAL;
+
+ memcg->oom_score_adj = (short)oom_score_adj;
+
+ return nbytes;
+}
+
static int memory_events_show(struct seq_file *m, void *v)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
@@ -5298,6 +5328,12 @@ static struct cftype memory_files[] = {
.write = memory_oom_kill_all_tasks_write,
},
{
+ .name = "oom_score_adj",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = memory_oom_score_adj_show,
+ .write = memory_oom_score_adj_write,
+ },
+ {
.name = "events",
.flags = CFTYPE_NOT_ON_ROOT,
.file_offset = offsetof(struct mem_cgroup, events_file),
--
2.7.4

2017-06-04 19:40:05

by Vladimir Davydov

Subject: Re: [RFC PATCH v2 5/7] mm, oom: introduce oom_score_adj for memory cgroups

On Thu, Jun 01, 2017 at 07:35:13PM +0100, Roman Gushchin wrote:
> Introduce a per-memory-cgroup oom_score_adj setting.
> A read-write single value file which exits on non-root
> cgroups. The default is "0".
>
> It will have a similar meaning to a per-process value,
> available via /proc/<pid>/oom_score_adj.
> Should be in a range [-1000, 1000].

IMHO OOM scoring (not only the user API, but the logic as well) should
be introduced by a separate patch following the main one (#6) in the
series. Rationale: we might want to commit the main patch right away,
while postponing OOM scoring for later, because some people might find
the API controversial and needing a further, deeper discussion.