From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751510Ab1HYNuJ (ORCPT ); Thu, 25 Aug 2011 09:50:09 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:49995 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751030Ab1HYNuH (ORCPT ); Thu, 25 Aug 2011 09:50:07 -0400 Date: Thu, 25 Aug 2011 15:49:56 +0200 From: Pavel Machek To: "Rafael J. Wysocki" Cc: Dave Chinner , Jan Kara , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, LKML Subject: Re: [PATCH] fs / ext3: Always unlock updates in ext3_freeze() Message-ID: <20110825134956.GA10476@ucw.cz> References: <201108112329.23043.rjw@sisk.pl> <20110822130045.GC11264@atrey.karlin.mff.cuni.cz> <20110822231348.GS3162@dastard> <201108240018.32189.rjw@sisk.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201108240018.32189.rjw@sisk.pl> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi! > > > > The problem really isn't XFS specific, nor is it new - the fact is > > > > that any filesystem that has registered a shrinker or can do async > > > > work in the background post-sync is vulnerable to this problem. It's > > > > > > Should we avoid calling shrinkers while hibernating? > > > > If you like getting random OOM problems when hibernating, then go > > for it. Besides, shrinkers are used for more than just filesystems, > > so you might find you screw entire classes of users by doing this > > (eg everyone using intel graphics and 3D). > > > > > Or put BUG_ON()s into filesystem shrinkers so that this can not > > > happen? > > > > Definitely not. If your concern is filesystem shrinkers and you want > > a large hammer to hit the problem with then do your hibernate > > image allocation wih GFP_NOFS and the filesystem shrinkers will > > abort without doing anything. > > I think we can do that, actually. I believe we should, yes. Question is if it helps much, because various drivers (and userspace in case uswsusp?) will still trigger GFP_KERNEL allocations. Something like this? --- snapshot.c.ofic 2011-08-25 15:48:41.000000000 +0200 +++ snapshot.c 2011-08-25 15:49:07.000000000 +0200 @@ -1107,7 +1107,7 @@ /* Helper functions used for the shrinking of memory. */ -#define GFP_IMAGE (GFP_KERNEL | __GFP_NOWARN) +#define GFP_IMAGE (GFP_NODS | __GFP_NOWARN) /** * preallocate_image_pages - Allocate a number of pages for hibernation image -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html