Re: [PATCH memcg 2/3] memcg: remove charge forcinig for dying tasks

Michal Hocko
2021-10-20T12:41:49Z

On Wed 20-10-21 15:13:46, Vasily Averin wrote:
> ToDo: should we keep task_is_dying() in mem_cgroup_out_of_memory() ?
>
> Signed-off-by: Vasily Averin <vvs-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
> ---
> mm/memcontrol.c | 20 +++++++-------------
> 1 file changed, 7 insertions(+), 13 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 6da5020a8656..74a7379dbac1 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -239,7 +239,7 @@ enum res_type {
> iter != NULL; \
> iter = mem_cgroup_iter(NULL, iter, NULL))
>
> -static inline bool should_force_charge(void)
> +static inline bool task_is_dying(void)
> {
> return tsk_is_oom_victim(current) || fatal_signal_pending(current) ||
> (current->flags & PF_EXITING);
> @@ -1575,7 +1575,7 @@ static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
> * A few threads which were not waiting at mutex_lock_killable() can
> * fail to bail out. Therefore, check again after holding oom_lock.
> */
> - ret = should_force_charge() || out_of_memory(&oc);
> + ret = task_is_dying() || out_of_memory(&oc);

Why are you keeping the task_is_dying check here? IIRC I have already
pointed out that out_of_memory already has some means to do a bypass
when needed.
--
Michal Hocko
SUSE Labs