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 0B93A6B002D for ; Wed, 16 Nov 2011 13:42:04 -0500 (EST) Received: by iaek3 with SMTP id k3so1368903iae.14 for ; Wed, 16 Nov 2011 10:42:02 -0800 (PST) Date: Wed, 16 Nov 2011 10:41:57 -0800 From: Tejun Heo Subject: Re: [PATCH v2] PM/Memory-hotplug: Avoid task freezing failures Message-ID: <20111116184157.GA25497@google.com> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4EC3FFC4.2010904@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: "Srivatsa S. Bhat" 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 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. Maybe just throw in msleep(10) there with fat ugly comment explaining why the hack is necessary? Thanks. -- tejun -- 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