From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758374AbYESW6v (ORCPT ); Mon, 19 May 2008 18:58:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762029AbYESW60 (ORCPT ); Mon, 19 May 2008 18:58:26 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.31.123]:35903 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757785AbYESW6Z (ORCPT ); Mon, 19 May 2008 18:58:25 -0400 Date: Tue, 20 May 2008 00:59:11 +0200 From: Pavel Machek To: "Rafael J. Wysocki" Cc: Matthew Wilcox , pm list , Ingo Molnar , Len Brown , LKML , Matt Helsley , Cedric Le Goater , Paul Menage , Andrew Morton , Alan Stern , Liam Howlett Subject: Re: [RFC][PATCH 2/2] Freezer: Try to handle killable tasks Message-ID: <20080519225910.GC2315@elf.ucw.cz> References: <200805070003.56387.rjw@sisk.pl> <200805070007.56998.rjw@sisk.pl> <20080507135333.GS19219@parisc-linux.org> <200805072041.20210.rjw@sisk.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200805072041.20210.rjw@sisk.pl> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 2008-05-07 20:41:19, Rafael J. Wysocki wrote: > On Wednesday, 7 of May 2008, Matthew Wilcox wrote: > > On Wed, May 07, 2008 at 12:07:55AM +0200, Rafael J. Wysocki wrote: > > > The introduction of TASK_KILLABLE allows the freezer to work in some situation > > > that it could not handle before. > > > > > > Make the freezer handle killable tasks and add try_to_freeze() in some places > > > where it is safe to freeze a (killable) task. Introduce the > > > wait_event_killable_freezable() macro to be used wherever the freezing of > > > a waiting killable task is desirable. > > > > Why do you say that TASK_KILLABLE allows the freezer to work in some > > situations where it couldn't before? If something's using one of the > > killable functions, it means that it knows how to clean up and unwind > > gracefully if the task receives a fatal signal. I don't understand what > > connection there is to the freezer. > > The reason why we don't freeze uninterruptible tasks is that we don't know > why they are in that state. If one of tasks is uninterruptible for a > relatively long time, that may indicate a non-recoverable error making it > dangerous to put the system into a sleep state. If the task is killable, > though, the situation is recoverable. ....but the task may still hold some locks, so we can't "just freeze it". Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html