From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762333AbXGEUMz (ORCPT ); Thu, 5 Jul 2007 16:12:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757501AbXGEUMs (ORCPT ); Thu, 5 Jul 2007 16:12:48 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:55096 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758951AbXGEUMr convert rfc822-to-8bit (ORCPT ); Thu, 5 Jul 2007 16:12:47 -0400 From: "Rafael J. Wysocki" To: Miklos Szeredi Subject: Re: [linux-pm] Re: [PATCH] Remove process freezer from suspend to RAM pathway Date: Thu, 5 Jul 2007 22:19:59 +0200 User-Agent: KMail/1.9.5 Cc: oliver@neukum.org, pavel@ucw.cz, paulus@samba.org, stern@rowland.harvard.edu, johannes@sipsolutions.net, linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org, mjg59@srcf.ucam.org, benh@kernel.crashing.org References: <18059.10554.955290.148535@cargo.ozlabs.ibm.com> <200707052138.56920.oliver@neukum.org> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8BIT Content-Disposition: inline Message-Id: <200707052220.00555.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, 5 July 2007 21:44, Miklos Szeredi wrote: > > Am Donnerstag, 5. Juli 2007 schrieb Miklos Szeredi: > > > > > Actually fuse allows SIGKILL, because it's always fatal, and the > > > > > syscall may not be restarted. > > > > > > > > I think you want to stick try_to_freeze() at the same places where you > > > > do SIGKILL handling. That should solve the 'syslogd is unfreezeable' > > > > problem. > > > > > > I could, but it would not solve the general problem.  Namely, that the > > > presence of fuse imposes a certain ordering in which userspace tasks > > > have to be frozen.  And it is not possible to know this ordering. > > > > Actually, why do you need this? There is no absolute need that you > > finish the request. You must either finish the request or let yourself > > be frozen. > > > > A quick look through fuse reveals principally request_wait_answer() > > And maybe a few other places. Is there some hidden reason you cannot > > handle being frozen here? > > Yes, fuse could handle being frozen there. However that would only > solve part of the problem: an operation waiting for a reply could be > holding a VFS mutex and some other task may be blocked on that mutex. > > How would you solve freezing those tasks? How probable is this situation? Greetings, Rafael -- "Premature optimization is the root of all evil." - Donald Knuth