From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id A36D76B002D for ; Wed, 16 Nov 2011 14:05:46 -0500 (EST) Received: from /spool/local by e28smtp05.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 17 Nov 2011 00:35:42 +0530 Received: from d28av01.in.ibm.com (d28av01.in.ibm.com [9.184.220.63]) by d28relay01.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id pAGJ5bHS4866088 for ; Thu, 17 Nov 2011 00:35:37 +0530 Received: from d28av01.in.ibm.com (loopback [127.0.0.1]) by d28av01.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id pAGJ5bij031215 for ; Thu, 17 Nov 2011 00:35:37 +0530 Message-ID: <4EC40980.90207@linux.vnet.ibm.com> Date: Thu, 17 Nov 2011 00:35:36 +0530 From: "Srivatsa S. Bhat" MIME-Version: 1.0 Subject: Re: [PATCH v2] PM/Memory-hotplug: Avoid task freezing failures References: <20111116115515.25945.35368.stgit@srivatsabhat.in.ibm.com> <20111116162601.GB18919@google.com> <4EC3F146.7050801@linux.vnet.ibm.com> <20111116174302.GD18919@google.com> <4EC3FFC4.2010904@linux.vnet.ibm.com> <20111116184157.GA25497@google.com> In-Reply-To: <20111116184157.GA25497@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: rjw@sisk.pl, 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 11/17/2011 12:11 AM, Tejun Heo wrote: > Hello, > > On Wed, Nov 16, 2011 at 11:54:04PM +0530, Srivatsa S. Bhat wrote: >> Ok, so by "proper solution", are you referring to a totally different >> method (than grabbing pm_mutex) to implement mutual exclusion between >> subsystems and suspend/hibernation, something like the suspend blockers >> stuff and friends? >> Or are you hinting at just the existing code itself being fixed more >> properly than what this patch does, to avoid having side effects like >> you pointed out? > > Oh, nothing fancy. Just something w/o busy looping would be fine. > The stinking thing is we don't have mutex_lock_freezable(). Lack of > proper freezable interface seems to be a continuing problem and I'm > not sure what the proper solution should be at this point. Maybe we > should promote freezable to a proper task state. Maybe freezable > kthread is a bad idea to begin with. Maybe instead of removing > freezable_with_signal() we should make that default, that way, > freezable can hitch on the pending signal handling (this creates > another set of problems tho - ie. who's responsible for clearing > TIF_SIGPENDING?). I don't know. > Thanks a lot for the explanation! I now get an idea about your thoughts on the fundamental issues with the freezer that are causing a broad range of problems... Hmm, definitely something to ponder over... > Maybe just throw in msleep(10) there with fat ugly comment explaining > why the hack is necessary? > Hehe, that surely sounds like the simplest of all the approaches you suggested ;-) I'll add this to the while loop in the patch and repost it, hoping we can solve the fundamental issues effectively at a later time. 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752891Ab1KPTFo (ORCPT ); Wed, 16 Nov 2011 14:05:44 -0500 Received: from e28smtp08.in.ibm.com ([122.248.162.8]:32822 "EHLO e28smtp08.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752567Ab1KPTFm (ORCPT ); Wed, 16 Nov 2011 14:05:42 -0500 Message-ID: <4EC40980.90207@linux.vnet.ibm.com> Date: Thu, 17 Nov 2011 00:35:36 +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: rjw@sisk.pl, 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 v2] PM/Memory-hotplug: Avoid task freezing failures References: <20111116115515.25945.35368.stgit@srivatsabhat.in.ibm.com> <20111116162601.GB18919@google.com> <4EC3F146.7050801@linux.vnet.ibm.com> <20111116174302.GD18919@google.com> <4EC3FFC4.2010904@linux.vnet.ibm.com> <20111116184157.GA25497@google.com> In-Reply-To: <20111116184157.GA25497@google.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit x-cbid: 11111619-2000-0000-0000-0000015200D8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/17/2011 12:11 AM, Tejun Heo wrote: > Hello, > > On Wed, Nov 16, 2011 at 11:54:04PM +0530, Srivatsa S. Bhat wrote: >> Ok, so by "proper solution", are you referring to a totally different >> method (than grabbing pm_mutex) to implement mutual exclusion between >> subsystems and suspend/hibernation, something like the suspend blockers >> stuff and friends? >> Or are you hinting at just the existing code itself being fixed more >> properly than what this patch does, to avoid having side effects like >> you pointed out? > > Oh, nothing fancy. Just something w/o busy looping would be fine. > The stinking thing is we don't have mutex_lock_freezable(). Lack of > proper freezable interface seems to be a continuing problem and I'm > not sure what the proper solution should be at this point. Maybe we > should promote freezable to a proper task state. Maybe freezable > kthread is a bad idea to begin with. Maybe instead of removing > freezable_with_signal() we should make that default, that way, > freezable can hitch on the pending signal handling (this creates > another set of problems tho - ie. who's responsible for clearing > TIF_SIGPENDING?). I don't know. > Thanks a lot for the explanation! I now get an idea about your thoughts on the fundamental issues with the freezer that are causing a broad range of problems... Hmm, definitely something to ponder over... > Maybe just throw in msleep(10) there with fat ugly comment explaining > why the hack is necessary? > Hehe, that surely sounds like the simplest of all the approaches you suggested ;-) I'll add this to the while loop in the patch and repost it, hoping we can solve the fundamental issues effectively at a later time. Thanks, Srivatsa S. Bhat