From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758962AbZEEXqt (ORCPT ); Tue, 5 May 2009 19:46:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757566AbZEEXqd (ORCPT ); Tue, 5 May 2009 19:46:33 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:39858 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754933AbZEEXqb (ORCPT ); Tue, 5 May 2009 19:46:31 -0400 Date: Tue, 5 May 2009 16:40:28 -0700 From: Andrew Morton To: "Rafael J. Wysocki" Cc: rientjes@google.com, 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 Subject: Re: [PATCH 1/5] mm: Add __GFP_NO_OOM_KILL flag Message-Id: <20090505164028.e9d807a1.akpm@linux-foundation.org> In-Reply-To: <200905060120.35698.rjw@sisk.pl> References: <200905060019.36542.rjw@sisk.pl> <20090505153739.2cc9d244.akpm@linux-foundation.org> <200905060120.35698.rjw@sisk.pl> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.20; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 6 May 2009 01:20:34 +0200 "Rafael J. Wysocki" wrote: > On Wednesday 06 May 2009, Andrew Morton wrote: > > On Wed, 6 May 2009 00:19:35 +0200 > > "Rafael J. Wysocki" wrote: > > > > > > > + && !processes_are_frozen()) { > > > > > if (!try_set_zone_oom(zonelist, gfp_mask)) { > > > > > schedule_timeout_uninterruptible(1); > > > > > goto restart; > > > > > > > > Cool, that looks like the semantics of __GFP_NO_OOM_KILL without requiring > > > > a new gfp flag. Thanks. > > > > > > Well, you're welcome. > > > > > > BTW, I think that Andrew was actually right when he asked if I checked whether > > > the existing __GFP_NORETRY would work as-is for __GFP_FS set and > > > __GFP_NORETRY unset. Namely, in that case we never reach the code before > > > nopage: that checks __GFP_NORETRY, do we? > > > > > > So I think we shouldn't modify the 'else if' condition above and check for > > > !processes_are_frozen() at the beginning of the block below. > > > > Confused. > > > > I'm suspecting that hibernation can allocate its pages with > > __GFP_FS|__GFP_WAIT|__GFP_NORETRY|__GFP_NOWARN, and the page allocator > > will dtrt: no oom-killings. > > > > In which case, processes_are_frozen() is not needed at all? > > __GFP_NORETRY alone causes it to fail relatively quickly, but I'll try with > the combination. OK. __GFP_WAIT is the big hammer. > Anyway, even if the hibernation code itself doesn't trigger the OOM killer, > but anyone else allocates memory in parallel or after we've preallocated the > image memory, that may still trigger it. So it seems processes_are_frozen() > may still be useful? Could be. But only kernel threads are active at this time (yes?), and they won't have much work to do because userspace is asleep. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [PATCH 1/5] mm: Add __GFP_NO_OOM_KILL flag Date: Tue, 5 May 2009 16:40:28 -0700 Message-ID: <20090505164028.e9d807a1.akpm@linux-foundation.org> References: <200905060019.36542.rjw@sisk.pl> <20090505153739.2cc9d244.akpm@linux-foundation.org> <200905060120.35698.rjw@sisk.pl> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200905060120.35698.rjw-KKrjLPT3xs0@public.gmane.org> Sender: kernel-testers-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: "Rafael J. Wysocki" Cc: rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, 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 Wed, 6 May 2009 01:20:34 +0200 "Rafael J. Wysocki" wrote: > On Wednesday 06 May 2009, Andrew Morton wrote: > > On Wed, 6 May 2009 00:19:35 +0200 > > "Rafael J. Wysocki" wrote: > > > > > > > + && !processes_are_frozen()) { > > > > > if (!try_set_zone_oom(zonelist, gfp_mask)) { > > > > > schedule_timeout_uninterruptible(1); > > > > > goto restart; > > > > > > > > Cool, that looks like the semantics of __GFP_NO_OOM_KILL without requiring > > > > a new gfp flag. Thanks. > > > > > > Well, you're welcome. > > > > > > BTW, I think that Andrew was actually right when he asked if I checked whether > > > the existing __GFP_NORETRY would work as-is for __GFP_FS set and > > > __GFP_NORETRY unset. Namely, in that case we never reach the code before > > > nopage: that checks __GFP_NORETRY, do we? > > > > > > So I think we shouldn't modify the 'else if' condition above and check for > > > !processes_are_frozen() at the beginning of the block below. > > > > Confused. > > > > I'm suspecting that hibernation can allocate its pages with > > __GFP_FS|__GFP_WAIT|__GFP_NORETRY|__GFP_NOWARN, and the page allocator > > will dtrt: no oom-killings. > > > > In which case, processes_are_frozen() is not needed at all? > > __GFP_NORETRY alone causes it to fail relatively quickly, but I'll try with > the combination. OK. __GFP_WAIT is the big hammer. > Anyway, even if the hibernation code itself doesn't trigger the OOM killer, > but anyone else allocates memory in parallel or after we've preallocated the > image memory, that may still trigger it. So it seems processes_are_frozen() > may still be useful? Could be. But only kernel threads are active at this time (yes?), and they won't have much work to do because userspace is asleep.