Introduce a per-memory-cgroup oom_priority setting: an integer number within the [-10000, 10000] range, which defines the order in which the OOM killer selects victim memory cgroups. OOM killer prefers memory cgroups with larger priority if they are populated with elegible tasks. The oom_priority value is compared within sibling cgroups. The root cgroup has the oom_priority 0, which cannot be changed. Signed-off-by: Roman Gushchin <guro@xxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Cc: kernel-team@xxxxxx Cc: cgroups@xxxxxxxxxxxxxxx Cc: linux-doc@xxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Cc: linux-mm@xxxxxxxxx --- include/linux/memcontrol.h | 3 +++ mm/memcontrol.c | 55 ++++++++++++++++++++++++++++++++++++++++++++-- 2 files changed, 56 insertions(+), 2 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index b21bbb0edc72..d31ac58e08ad 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -206,6 +206,9 @@ struct mem_cgroup { /* cached OOM score */ long oom_score; + /* OOM killer priority */ + short oom_priority; + /* handle for "memory.events" */ struct cgroup_file events_file; diff --git a/mm/memcontrol.c b/mm/memcontrol.c index ba72d1cf73d0..2c1566995077 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2710,12 +2710,21 @@ static void select_victim_memcg(struct mem_cgroup *root, struct oom_control *oc) for (;;) { struct cgroup_subsys_state *css; struct mem_cgroup *memcg = NULL; + short prio = SHRT_MIN; long score = LONG_MIN; css_for_each_child(css, &root->css) { struct mem_cgroup *iter = mem_cgroup_from_css(css); - if (iter->oom_score > score) { + if (iter->oom_score == 0) + continue; + + if (iter->oom_priority > prio) { + memcg = iter; + prio = iter->oom_priority; + score = iter->oom_score; + } else if (iter->oom_priority == prio && + iter->oom_score > score) { memcg = iter; score = iter->oom_score; } @@ -2782,7 +2791,15 @@ bool mem_cgroup_select_oom_victim(struct oom_control *oc) * For system-wide OOMs we should consider tasks in the root cgroup * with oom_score larger than oc->chosen_points. */ - if (!oc->memcg) { + if (!oc->memcg && !(oc->chosen_memcg && + oc->chosen_memcg->oom_priority > 0)) { + /* + * Root memcg has priority 0, so if chosen memcg has lower + * priority, any task in root cgroup is preferable. + */ + if (oc->chosen_memcg && oc->chosen_memcg->oom_priority < 0) + oc->chosen_points = 0; + select_victim_root_cgroup_task(oc); if (oc->chosen && oc->chosen_memcg) { @@ -5373,6 +5390,34 @@ static ssize_t memory_oom_kill_all_tasks_write(struct kernfs_open_file *of, return nbytes; } +static int memory_oom_priority_show(struct seq_file *m, void *v) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); + + seq_printf(m, "%d\n", memcg->oom_priority); + + return 0; +} + +static ssize_t memory_oom_priority_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_priority; + int err; + + err = kstrtoint(strstrip(buf), 0, &oom_priority); + if (err) + return err; + + if (oom_priority < -10000 || oom_priority > 10000) + return -EINVAL; + + memcg->oom_priority = (short)oom_priority; + + return nbytes; +} + static int memory_events_show(struct seq_file *m, void *v) { struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); @@ -5499,6 +5544,12 @@ static struct cftype memory_files[] = { .write = memory_oom_kill_all_tasks_write, }, { + .name = "oom_priority", + .flags = CFTYPE_NOT_ON_ROOT, + .seq_show = memory_oom_priority_show, + .write = memory_oom_priority_write, + }, + { .name = "events", .flags = CFTYPE_NOT_ON_ROOT, .file_offset = offsetof(struct mem_cgroup, events_file), -- 2.13.3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>