From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933903AbXCUXTH (ORCPT ); Wed, 21 Mar 2007 19:19:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933648AbXCUXTH (ORCPT ); Wed, 21 Mar 2007 19:19:07 -0400 Received: from ug-out-1314.google.com ([66.249.92.173]:19097 "EHLO ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933903AbXCUXTE (ORCPT ); Wed, 21 Mar 2007 19:19:04 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:from:to:subject:date:user-agent:cc:references:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:message-id; b=ABesS+D10ObMlysjhvx6WOEnrEK+fIB50iPlt5eP7d/57DAHbXrQCqXUVeDjGgJNAdvzaVOf3eLjWLU4GyQztQ0cTqyhXp1NWfsbURprQVz361DYWjRbbT36uN8uyXi3w/T4R181TOLANOTPVyH0Xc8U9WMvp2F6eXLlzY554sQ= From: Maxim To: "Rafael J. Wysocki" Subject: Re: [BUG] Code reordering in swsusp breaks suspend on SMP systems Date: Thu, 22 Mar 2007 01:18:56 +0200 User-Agent: KMail/1.9.6 Cc: linux-kernel@vger.kernel.org, Pavel Machek , nigel@nigel.suspend2.net References: <200703211840.53242.maximlevitsky@gmail.com> <200703212339.02972.rjw@sisk.pl> <200703220109.54719.maximlevitsky@gmail.com> In-Reply-To: <200703220109.54719.maximlevitsky@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200703220118.56503.maximlevitsky@gmail.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 22 March 2007 01:09:54 Maxim wrote: > On Thursday 22 March 2007 00:39:02 you wrote: > > On Wednesday, 21 March 2007 23:21, Pavel Machek wrote: > > > Hi! > > > > > > > Starting with 2.6.21-rc1 suspend to ram and disk doesn't work anymore on my system. > > > > > > > > I did a git-bisect and found that those commits break it: > > > > > > > > e3c7db621bed4afb8e231cb005057f2feb5db557 - [PATCH] [PATCH] PM: Change code ordering in main.c > > > > ed746e3b18f4df18afa3763155972c5835f284c5 - [PATCH] [PATCH] swsusp: Change code ordering in disk.c > > > > 259130526c267550bc365d3015917d90667732f1 - [PATCH] [PATCH] swsusp: Change code ordering in user.c > > > > > > > > > > (Yep, it was in my "to analyze" queue). > > > > > > > I already reported about it, but now i know the reason why suspend breaks. > > > > > > > > The problem is that both cpu_up/cpu_down were allowed to sleep until now, > > > > and it did work because those functions could be called only in process context > > > > (the one that writes to /sys/devices/system/cpu/cpu*/online) or idle thread that does smp_init()). > > > > > > > > But now they are called _after_ all tasks were suspended, so if cpu_down tries for example to take a lock > > > > that is taken by different process, it can't since the different proccess is frozen and can't release the lock. > > > > > > > > > > Thanks for detailed explanation. > > > > > > ...but, on my machine suspend works ok in -rc4. I'm not seeing this. > > > > > > ...by design, "frozen" tasks must not hold any locks. If frozen task > > > holds a lock, that's a bug. > > > > > > > Or, it is also possible to revert this change. > > > > > > Are you using xfs? > > > > Well, this is the only case that can trigger it. There are no other freezable > > workqueues. > > > > Greetings, > > Rafael > > > > Hello, > > Yes, you are right and it is XFS > > System suspends and resumes with xfs and your patch correctly, > > Of course I need to mention that I had to unload microcode update driver because it prevented resume, > because it calls firmware loader helper, and again sleeps on lock > > And also I noticed now that system oopses on second attempt to suspend ether to ram or disk > in pci_restore_msi_state which is called indirectly by ahci_pci_device_resume, I will investigate this soon. > > Thanks a lot, > Regards, > Maxim Levitsky > > And I forgot to cc here too, I didn't intend to send private email. Regards, Maxim Levitsky