From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753262Ab1KUSCI (ORCPT ); Mon, 21 Nov 2011 13:02:08 -0500 Received: from e28smtp09.in.ibm.com ([122.248.162.9]:53685 "EHLO e28smtp09.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752315Ab1KUSCG (ORCPT ); Mon, 21 Nov 2011 13:02:06 -0500 Message-ID: <4ECA9217.7020205@linux.vnet.ibm.com> Date: Mon, 21 Nov 2011 23:31:59 +0530 From: "Srivatsa S. Bhat" User-Agent: Mozilla/5.0 (X11; Linux i686; rv:7.0) Gecko/20110927 Thunderbird/7.0 MIME-Version: 1.0 To: Tejun Heo CC: "Rafael J. Wysocki" , pavel@ucw.cz, lenb@kernel.org, ak@linux.intel.com, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v3] PM/Memory-hotplug: Avoid task freezing failures References: <20111117083042.11419.19871.stgit@srivatsabhat.in.ibm.com> <201111192257.19763.rjw@sisk.pl> <4EC8984E.30005@linux.vnet.ibm.com> <201111201124.17528.rjw@sisk.pl> <4EC9D557.9090008@linux.vnet.ibm.com> <20111121164006.GB15314@google.com> <4ECA84A8.5030005@linux.vnet.ibm.com> <20111121175242.GE15314@google.com> In-Reply-To: <20111121175242.GE15314@google.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit x-cbid: 11112118-2674-0000-0000-000001CC7A73 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/21/2011 11:22 PM, Tejun Heo wrote: > Hello, > > On Mon, Nov 21, 2011 at 10:34:40PM +0530, Srivatsa S. Bhat wrote: >>>> I haven't tested this solution yet. Let me know if this solution looks >>>> good and I'll send it out as a patch after testing and analyzing some >>>> corner cases, if any. >> >> I tested this, and it works great! I'll send the patch in some time. > > Awesome. > >>> * I think it would be better to remove direct access to pm_mutex and >>> use [un]lock_system_sleep() universally. I don't think hinging it >>> on CONFIG_HIBERNATE_CALLBACKS buys us anything. >>> >> >> Which direct access to pm_mutex are you referring to? >> Other than suspend/hibernation call paths, I think mem-hotplug is the only >> subsystem trying to access pm_mutex. I haven't checked thoroughly though. >> >> But yes, using lock_system_sleep() for mutually excluding some code path >> from suspend/hibernation is good, and that is one reason why I wanted >> to fix this API ASAP. But as long as memory hotplug is the only direct user >> of pm_mutex, is it justified to remove the CONFIG_HIBERNATE_CALLBACKS >> restriction and make it generic? I don't know... >> >> Or, are you saying that we should use these APIs even in suspend/hibernate >> call paths? That's not such a bad idea either... > > Yeap, all. It's just confusing to have two different types of access > to a single lock and I don't believe CONFIG_HIBERNATE_CALLBACKS is a > meaningful optimization in this case. > Ok that sounds good, I'll send a separate patch for that. Rafael, do you also agree that this would be better? Thanks, Srivatsa S. Bhat