On Wed, Oct 04, 2017 at 04:46:35PM +0100, Roman Gushchin wrote: > Traditionally, the OOM killer is operating on a process level. > Under oom conditions, it finds a process with the highest oom score > and kills it. > > This behavior doesn't suit well the system with many running > containers: > > 1) There is no fairness between containers. A small container with > few large processes will be chosen over a large one with huge > number of small processes. > > 2) Containers often do not expect that some random process inside > will be killed. In many cases much safer behavior is to kill > all tasks in the container. Traditionally, this was implemented > in userspace, but doing it in the kernel has some advantages, > especially in a case of a system-wide OOM. > > To address these issues, the cgroup-aware OOM killer is introduced. > > Under OOM conditions, it looks for the biggest leaf memory cgroup > and kills the biggest task belonging to it. The following patches > will extend this functionality to consider non-leaf memory cgroups > as well, and also provide an ability to kill all tasks belonging > to the victim cgroup. > > The root cgroup is treated as a leaf memory cgroup, so it's score > is compared with leaf memory cgroups. > Due to memcg statistics implementation a special algorithm > is used for estimating it's oom_score: we define it as maximum > oom_score of the belonging tasks. > > Signed-off-by: Roman Gushchin <[email protected]> > Cc: Michal Hocko <[email protected]> > Cc: Vladimir Davydov <[email protected]> > Cc: Johannes Weiner <[email protected]> > Cc: Tetsuo Handa <[email protected]> > Cc: David Rientjes <[email protected]> > Cc: Andrew Morton <[email protected]> > Cc: Tejun Heo <[email protected]> > Cc: [email protected] > Cc: [email protected] > Cc: [email protected] > Cc: [email protected] > Cc: [email protected]
This looks good to me. Acked-by: Johannes Weiner <[email protected]> I just have one question: > @@ -828,6 +828,12 @@ static void __oom_kill_process(struct task_struct > *victim) > struct mm_struct *mm; > bool can_oom_reap = true; > > + if (is_global_init(victim) || (victim->flags & PF_KTHREAD) || > + victim->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) { > + put_task_struct(victim); > + return; > + } > + > p = find_lock_task_mm(victim); > if (!p) { > put_task_struct(victim); Is this necessary? The callers of this function use oom_badness() to find a victim, and that filters init, kthread, OOM_SCORE_ADJ_MIN.
