Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755697Ab1CLVU4 (ORCPT ); Sat, 12 Mar 2011 16:20:56 -0500 Received: from mx1.redhat.com ([209.132.183.28]:39664 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755004Ab1CLVUz (ORCPT ); Sat, 12 Mar 2011 16:20:55 -0500 Date: Sat, 12 Mar 2011 22:11:43 +0100 From: Oleg Nesterov To: Andrew Vagin Cc: Pavel Emelyanov , Andrey Vagin , Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Andrew Morton , David Rientjes , KAMEZAWA Hiroyuki , KOSAKI Motohiro , linux-kernel@vger.kernel.org, Nick Piggin Subject: Re: + x86-mm-handle-mm_fault_error-in-kernel-space.patch added to -mm tree Message-ID: <20110312211143.GA27460@redhat.com> References: <20110310142812.GA25224@redhat.com> <4D7926C9.9070206@parallels.com> <20110311111931.GA16052@redhat.com> <4D7A2FED.3060200@gmail.com> <20110311165700.GA30929@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110311165700.GA30929@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1517 Lines: 46 On 03/11, Oleg Nesterov wrote: > > On 03/11, Andrew Vagin wrote: > > > > > The point is, if current was _NOT_ killed we should follow the current > pagefault_out_of_memory() logic or remove pagefault_out_of_memory() > completely. Yes, and I still think this is valid. And thus I still think the patch should be changed (btw, this problem is not x86 specific). However, > >> Why do you think the current task should be killed? In this case we > >> do not need oom-killer at all, we could always kill the caller of > >> alloc_page/etc. > > > > You don't understand. alloc_page calls oom-killer himself, then try > > allocate memory again. Pls look at __alloc_pages_slowpath(). > > __alloc_pages_slowpat may fail if order > 3 || gfp_mask & __GFP_NOFAIL > > || test_thread_flag(TIF_MEMDIE) > > Andrew, please, I know this. Hmm. It turns out I do not ;) I thought I can find the case when handle_mm_fault() returns VM_FAULT_OOM and the caller is not killed, but I can't. I do not really understand mem_cgroup_handle_oom/etc, but it seems we always retry indefinitely even with mem_cgroup's. mm/hugetlb.c looks fine too... So, I have to apologize, I am starting to think you are right. Maybe someone could explain why pagefault_out_of_memory() is still needed? Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/