I would really suggest you to stick with the changelog I have suggested.
On Wed 01-11-17 20:54:27, Tetsuo Handa wrote:
[...]
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index 26add8a..118ecdb 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -870,6 +870,19 @@ static void oom_kill_process(struct oom_control *oc, const char *message)
> }
> task_unlock(p);
>
> + /*
> + * Try really last second allocation attempt after we selected an OOM
> + * victim, for somebody might have managed to free memory while we were
> + * selecting an OOM victim which can take quite some time.
> + */
> + if (oc->ac) {
> + oc->page = alloc_pages_before_oomkill(oc);
I would stick the oc->ac check inside alloc_pages_before_oomkill.
> + if (oc->page) {
> + put_task_struct(p);
> + return;
> + }
> + }
> +
> if (__ratelimit(&oom_rs))
> dump_header(oc, p);
>
> @@ -1081,6 +1094,16 @@ bool out_of_memory(struct oom_control *oc)
> select_bad_process(oc);
> /* Found nothing?!?! Either we hang forever, or we panic. */
> if (!oc->chosen && !is_sysrq_oom(oc) && !is_memcg_oom(oc)) {
> + /*
> + * Try really last second allocation attempt, for somebody
> + * might have managed to free memory while we were trying to
> + * find an OOM victim.
> + */
> + if (oc->ac) {
> + oc->page = alloc_pages_before_oomkill(oc);
> + if (oc->page)
> + return true;
> + }
> dump_header(oc, NULL);
> panic("Out of memory and no killable processes...\n");
> }
Also, is there any strong reason to not do the last allocation after
select_bad_process rather than having two call sites? I would understand
that if you wanted to catch for_each_thread inside oom_kill_process but
you are not doing that.
[...]
--
Michal Hocko
SUSE Labs
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