From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756449AbZEHX4a (ORCPT ); Fri, 8 May 2009 19:56:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753573AbZEHX4U (ORCPT ); Fri, 8 May 2009 19:56:20 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:47966 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752964AbZEHX4T (ORCPT ); Fri, 8 May 2009 19:56:19 -0400 From: "Rafael J. Wysocki" To: David Rientjes Subject: Re: [PATCH 1/5] mm: Add __GFP_NO_OOM_KILL flag Date: Sat, 9 May 2009 01:55:43 +0200 User-Agent: KMail/1.11.2 (Linux/2.6.30-rc4-rjw; KDE/4.2.2; x86_64; ; ) Cc: Andrew Morton , fengguang.wu@intel.com, linux-pm@lists.linux-foundation.org, pavel@ucw.cz, torvalds@linux-foundation.org, jens.axboe@oracle.com, alan-jenkins@tuffmail.co.uk, linux-kernel@vger.kernel.org, kernel-testers@vger.kernel.org References: <200905072218.50782.rjw@sisk.pl> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200905090155.44635.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 07 May 2009, David Rientjes wrote: > On Thu, 7 May 2009, Rafael J. Wysocki wrote: > > > OK, let's try with __GFP_NO_OOM_KILL first. If there's too much disagreement, > > I'll use the freezer-based approach instead. > > > > Third time I'm going to suggest this, and I'd like a response on why it's > not possible instead of being ignored. > > All of your tasks are in D state other than kthreads, right? That means > they won't be in the oom killer (thus no zones are oom locked), so you can > easily do this > > struct zone *z; > for_each_populated_zone(z) > zone_set_flag(z, ZONE_OOM_LOCKED); > > and then > > for_each_populated_zone(z) > zone_clear_flag(z, ZONE_OOM_LOCKED); > > The serialization is done with trylocks so this will never invoke the oom > killer because all zones in the allocator's zonelist will be oom locked. Well, that might have been a good idea if it actually had worked. :-( > Why does this not work for you? If I set image_size to something below "hard core working set" + totalreserve_pages, preallocate_image_memory() hangs the box (please refer to the last patch I sent, http://patchwork.kernel.org/patch/22423/). However, with the freezer-based disabling of the OOM killer it doesn't hang under the same test conditions. The difference appears to be that using your approach makes __alloc_pages_internal() loop forever between the !try_set_zone_oom() test and restart:, while it should go to nopage: in that situation. So, I think I'll stick to the Andrew's approach with using __GFP_NO_OOM_KILL. Thanks, Rafael From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH 1/5] mm: Add __GFP_NO_OOM_KILL flag Date: Sat, 9 May 2009 01:55:43 +0200 Message-ID: <200905090155.44635.rjw@sisk.pl> References: <200905072218.50782.rjw@sisk.pl> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Disposition: inline Sender: kernel-testers-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: Text/Plain; charset="us-ascii" To: David Rientjes Cc: Andrew Morton , fengguang.wu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, linux-pm-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, pavel-+ZI9xUNit7I@public.gmane.org, torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, jens.axboe-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, alan-jenkins-cCz0Lq7MMjm9FHfhHBbuYA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kernel-testers-u79uwXL29TY76Z2rM5mHXA@public.gmane.org On Thursday 07 May 2009, David Rientjes wrote: > On Thu, 7 May 2009, Rafael J. Wysocki wrote: > > > OK, let's try with __GFP_NO_OOM_KILL first. If there's too much disagreement, > > I'll use the freezer-based approach instead. > > > > Third time I'm going to suggest this, and I'd like a response on why it's > not possible instead of being ignored. > > All of your tasks are in D state other than kthreads, right? That means > they won't be in the oom killer (thus no zones are oom locked), so you can > easily do this > > struct zone *z; > for_each_populated_zone(z) > zone_set_flag(z, ZONE_OOM_LOCKED); > > and then > > for_each_populated_zone(z) > zone_clear_flag(z, ZONE_OOM_LOCKED); > > The serialization is done with trylocks so this will never invoke the oom > killer because all zones in the allocator's zonelist will be oom locked. Well, that might have been a good idea if it actually had worked. :-( > Why does this not work for you? If I set image_size to something below "hard core working set" + totalreserve_pages, preallocate_image_memory() hangs the box (please refer to the last patch I sent, http://patchwork.kernel.org/patch/22423/). However, with the freezer-based disabling of the OOM killer it doesn't hang under the same test conditions. The difference appears to be that using your approach makes __alloc_pages_internal() loop forever between the !try_set_zone_oom() test and restart:, while it should go to nopage: in that situation. So, I think I'll stick to the Andrew's approach with using __GFP_NO_OOM_KILL. Thanks, Rafael