Re: [RFC PATCH] mm/oom_kill: allow oom kill allocating task for non-global case

From: Michal Hocko
Date: Mon Jun 07 2021 - 15:01:34 EST


On Mon 07-06-21 17:31:03, Aaron Tomlin wrote:
> At the present time, in the context of memcg OOM, even when
> sysctl_oom_kill_allocating_task is enabled/or set, the "allocating"
> task cannot be selected, as a target for the OOM killer.
>
> This patch removes the restriction entirely.

This is a global oom policy not a memcg specific one so a historical
behavior would change. So I do not think we can change that. The policy
can be implemented on the memcg level but this would require a much more
detailed explanation of the usecase and the semantic (e.g. wrt.
hierarchical behavior etc).

> Signed-off-by: Aaron Tomlin <atomlin@xxxxxxxxxx>
> ---
> mm/oom_kill.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index eefd3f5fde46..3bae33e2d9c2 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -1089,9 +1089,9 @@ bool out_of_memory(struct oom_control *oc)
> oc->nodemask = NULL;
> check_panic_on_oom(oc);
>
> - if (!is_memcg_oom(oc) && sysctl_oom_kill_allocating_task &&
> - current->mm && !oom_unkillable_task(current) &&
> - oom_cpuset_eligible(current, oc) &&
> + if (sysctl_oom_kill_allocating_task && current->mm &&
> + !oom_unkillable_task(current) &&
> + oom_cpuset_eligible(current, oc) &&
> current->signal->oom_score_adj != OOM_SCORE_ADJ_MIN) {
> get_task_struct(current);
> oc->chosen = current;
> --
> 2.26.3

--
Michal Hocko
SUSE Labs