From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id D21006000C5 for ; Tue, 19 Jan 2010 04:04:51 -0500 (EST) Received: by ey-out-1920.google.com with SMTP id 26so631264eyw.6 for ; Tue, 19 Jan 2010 01:04:49 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <1263871194.724.520.camel@pasglop> References: <20100118110324.AE30.A69D9226@jp.fujitsu.com> <201001182155.09727.rjw@sisk.pl> <20100119101101.5F2E.A69D9226@jp.fujitsu.com> <1263871194.724.520.camel@pasglop> Date: Tue, 19 Jan 2010 10:04:49 +0100 Message-ID: <195c7a901001190104x164381f9v4a58d1fce70b17b6@mail.gmail.com> Subject: Re: [RFC][PATCH] PM: Force GFP_NOIO during suspend/resume (was: Re: [linux-pm] Memory allocations in .suspend became very unreliable) From: Bastien ROUCARIES Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org To: Benjamin Herrenschmidt Cc: KOSAKI Motohiro , "Rafael J. Wysocki" , Maxim Levitsky , linux-pm@lists.linux-foundation.org, LKML , linux-mm , Andrew Morton List-ID: On Tue, Jan 19, 2010 at 4:19 AM, Benjamin Herrenschmidt wrote: > On Tue, 2010-01-19 at 10:19 +0900, KOSAKI Motohiro wrote: >> I think the race happen itself is bad. memory and I/O subsystem can't solve such race >> elegantly. These doesn't know enough suspend state knowlege. I think the practical >> solution is that higher level design prevent the race happen. >> >> >> > My patch attempts to avoid these two problems as well as the problem with >> > drivers using GFP_KERNEL allocations during suspend which I admit might be >> > solved by reworking the drivers. >> >> Agreed. In this case, only drivers change can solve the issue. > > As I explained earlier, this is near to impossible since the allocations > are too often burried deep down the call stack or simply because the > driver doesn't know that we started suspending -another- driver... > > I don't think trying to solve those problems at the driver level is > realistic to be honest. This is one of those things where we really just > need to make allocators 'just work' from a driver perspective. 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. My 2 cents. Bastien -- 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