From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 7353D6B0082 for ; Wed, 20 Jan 2010 16:12:41 -0500 (EST) From: "Rafael J. Wysocki" Subject: Re: [RFC][PATCH] PM: Force GFP_NOIO during suspend/resume (was: Re: [linux-pm] Memory allocations in .suspend became very unreliable) Date: Wed, 20 Jan 2010 22:12:49 +0100 References: <20100118110324.AE30.A69D9226@jp.fujitsu.com> <1263943071.724.540.camel@pasglop> <201001201231.17540.oliver@neukum.org> In-Reply-To: <201001201231.17540.oliver@neukum.org> MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <201001202212.49925.rjw@sisk.pl> Sender: owner-linux-mm@kvack.org To: Oliver Neukum Cc: Benjamin Herrenschmidt , Bastien ROUCARIES , KOSAKI Motohiro , Maxim Levitsky , linux-pm@lists.linux-foundation.org, LKML , linux-mm , Andrew Morton List-ID: On Wednesday 20 January 2010, Oliver Neukum wrote: > Am Mittwoch, 20. Januar 2010 00:17:51 schrieb Benjamin Herrenschmidt: > > On Tue, 2010-01-19 at 10:04 +0100, Bastien ROUCARIES wrote: > > > Instead of masking bit could we only check if incompatible flags are > > > used during suspend, and warm deeply. Call stack will be therefore > > > identified, and we could have some metrics about such problem. > > > > > > It will be a debug option like lockdep but pretty low cost. > > > > I still believe it would just be a giant can of worms to require every > > call site of memory allocators to "know" whether suspend has been > > started or not.... Along the same reasons why we added that stuff for > > boot time allocs. > > But we have the freezer. So generally we don't require that knowledge. > We can expect no normal IO to happen. > The question is in the suspend paths. We never may use anything > but GFP_NOIO (and GFP_ATOMIC) in the suspend() path. We can > take care of that requirement in the allocator only if the whole system > is suspended. As soon as a driver does runtime power management, > it is on its own. If you start new kernel threads using the async framework, for example, GFP_KERNEL allocations are going to be used. As I said before, IMnshO , duplicating every piece of code that allocates memory and can be run during suspend/resume as well as in other circumstances doesn't make sense. Rafael -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org