Re: [patch 3/5] oom: less memdie

Andrew Morton
2006-10-12T22:04:00Z

On Thu, 12 Oct 2006 16:10:01 +0200 (CEST)
Nick Piggin <npiggin@suse.de> wrote:

> Don't cause all threads in all other thread groups to gain TIF_MEMDIE
> otherwise we'll get a thundering herd eating out memory reserve. This
> may not be the optimal scheme, but it fits our policy of allowing just
> one TIF_MEMDIE in the system at once.
>
> Signed-off-by: Nick Piggin <npiggin@suse.de>
>
> Index: linux-2.6/mm/oom_kill.c
> ===================================================================
> --- linux-2.6.orig/mm/oom_kill.c
> +++ linux-2.6/mm/oom_kill.c
> @@ -322,11 +322,12 @@ static int oom_kill_task(struct task_str
>
> /*
> * kill all processes that share the ->mm (i.e. all threads),
> - * but are in a different thread group.
> + * but are in a different thread group. Don't let them have access
> + * to memory reserves though, otherwise we might deplete all memory.
> */
> do_each_thread(g, q) {
> if (q->mm == mm && q->tgid != p->tgid)
> - __oom_kill_task(q, 1);
> + force_sig(SIGKILL, p);
> } while_each_thread(g, q);
>

Curious. How much testing did you do of this stuff? I assume there were
some observed problems. What were they, and what was the observed effect
of these changes?

Thanks.