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SubjectRe: [PATCH] oom: OOM-Killed process don't invoke pagefault-oom
Hi,

I don't think this should be required, because the oom killer does not
kill a new task if there is already one in memdie state.

If you have any further tweaks to the heuristic (such as a fatal signal
pending), then it should probably go in select_bad_process() or
somewhere like that.

Thanks,
Nick

On Thu, Jan 14, 2010 at 07:22:34PM +0900, KOSAKI Motohiro wrote:
>
> Nick, I've found this issue by code review. I'm glad if you review this
> patch.
>
> Thanks.
>
> =============================
> commit 1c0fe6e3 (invoke oom-killer from page fault) created
> page fault specific oom handler.
>
> But If OOM occur, alloc_pages() in page fault might return
> NULL. It mean page fault return VM_FAULT_OOM. But OOM Killer
> itself sholdn't invoke next OOM Kill. it is obviously strange.
>
> Plus, process exiting itself makes some free memory. we
> don't need kill another process.
>
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> Cc: Nick Piggin <npiggin@suse.de>
> Cc: Jeff Dike <jdike@addtoit.com>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> ---
> mm/oom_kill.c | 9 +++++++++
> 1 files changed, 9 insertions(+), 0 deletions(-)
>
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index 4f167b8..86cecdf 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -596,6 +596,15 @@ void pagefault_out_of_memory(void)
> {
> unsigned long freed = 0;
>
> + /*
> + * If the task was received SIGKILL while memory allocation, alloc_pages
> + * might return NULL and it cause page fault return VM_FAULT_OOM. But
> + * in such case, the task don't need kill any another task, it need
> + * just die.
> + */
> + if (fatal_signal_pending(current))
> + return;
> +
> blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
> if (freed > 0)
> /* Got some memory back in the last second. */
> --
> 1.6.5.2
>
>


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