From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id F2B906B002D for ; Mon, 21 Nov 2011 13:02:10 -0500 (EST) Received: from /spool/local by e28smtp02.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 21 Nov 2011 23:32:06 +0530 Received: from d28av05.in.ibm.com (d28av05.in.ibm.com [9.184.220.67]) by d28relay01.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id pALI21kM4632652 for ; Mon, 21 Nov 2011 23:32:01 +0530 Received: from d28av05.in.ibm.com (loopback [127.0.0.1]) by d28av05.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id pALI20dv011085 for ; Tue, 22 Nov 2011 05:02:01 +1100 Message-ID: <4ECA9217.7020205@linux.vnet.ibm.com> Date: Mon, 21 Nov 2011 23:31:59 +0530 From: "Srivatsa S. Bhat" MIME-Version: 1.0 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 Sender: owner-linux-mm@kvack.org List-ID: 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 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 -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org