Re: [patch 06/18] oom: avoid sending exiting tasks a SIGKILL

[Andrew Morton <akpm@linux-foundation.org>]

On Sun, 6 Jun 2010 15:34:22 -0700 (PDT)
David Rientjes <rientjes@google.com> wrote:

> It's unnecessary to SIGKILL a task that is already PF_EXITING and can
> actually cause a NULL pointer dereference of the sighand if it has already
> been detached.  Instead, simply set TIF_MEMDIE so it has access to memory
> reserves and can quickly exit as the comment implies.
> 
> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Signed-off-by: David Rientjes <rientjes@google.com>
> ---
>  mm/oom_kill.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -458,7 +458,7 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
>  	 * its children or threads, just set TIF_MEMDIE so it can die quickly
>  	 */
>  	if (p->flags & PF_EXITING) {
> -		__oom_kill_task(p, 0);
> +		set_tsk_thread_flag(p, TIF_MEMDIE);
>  		return 0;
>  	}

Well, we lose a lot of other stuff here.  We can set TIF_MEMDIE on the
is_global_init() task (how can that get PF_EXITING?).  We don't print
the "Killed process %d" info.  We don't bump the task's timeslice.

These are unchangelogged alterations and I for one can't tell whether
or not they were deliberate.

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