linux-kernel - Re: [PATCH] oom: Make coredump interruptible

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Message-ID: <20100603140357.GB3548@redhat.com>
Date:	Thu, 3 Jun 2010 16:03:57 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Roland McGrath <roland@...hat.com>
Cc:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>,
	David Rientjes <rientjes@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Nick Piggin <npiggin@...e.de>
Subject: Re: [PATCH] oom: Make coredump interruptible

On 06/02, Oleg Nesterov wrote:
>
> On 06/02, Roland McGrath wrote:
> >
> > > when select_bad_process() finds the task P to kill it can participate
> > > in the core dump (sleep in exit_mm), but we should somehow inform the
> > > thread which actually dumps the core: P->mm->core_state->dumper.
> >
> > Perhaps it should simply do that: if you would choose P to oom-kill, and
> > P->mm->core_state!=NULL, then choose P->mm->core_state->dumper instead.
>
> ... to set TIF_MEMDIE which should be checked in elf_core_dump().
>
> Probably yes.

Well, nothing can protect mm->core_state, the dumper owns it. Of course
we can add the locking, but this is not nice.

And again, perhaps MMF_OOMKILLED can be useful anyway.

So, I think this would be the most quick/simple fix for now.

Oleg.

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