From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762350AbXGFHcj (ORCPT ); Fri, 6 Jul 2007 03:32:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755783AbXGFHcc (ORCPT ); Fri, 6 Jul 2007 03:32:32 -0400 Received: from smtp-out001.kontent.com ([81.88.40.215]:59295 "EHLO smtp-out.kontent.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753431AbXGFHcb convert rfc822-to-8bit (ORCPT ); Fri, 6 Jul 2007 03:32:31 -0400 From: Oliver Neukum To: Benjamin Herrenschmidt Subject: Re: [linux-pm] Re: [PATCH] Remove process freezer from suspend to RAM pathway Date: Fri, 6 Jul 2007 09:32:30 +0200 User-Agent: KMail/1.9.7 Cc: Miklos Szeredi , pavel@ucw.cz, paulus@samba.org, stern@rowland.harvard.edu, johannes@sipsolutions.net, rjw@sisk.pl, linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org, mjg59@srcf.ucam.org References: <18059.10554.955290.148535@cargo.ozlabs.ibm.com> <1183676751.3388.96.camel@localhost.localdomain> In-Reply-To: <1183676751.3388.96.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8BIT Content-Disposition: inline Message-Id: <200707060932.31345.oliver@neukum.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Am Freitag, 6. Juli 2007 schrieb Benjamin Herrenschmidt: > > 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? > > That task is implicitely frozen... but the kernel doesn't know it and > thus the freezer timeouts or fails or deadlocks or whatever. > > The freezer could be made to ignore tasks that are sleeping in the > kernel assuming that if they go out of it, they'll ultimately reach > do_signal and freeze, but that means they can potentially still issues > IOs which is what the freezer tries to avoid ... > > Or the kernel could start tracking dependencies, but then, good luck > implementing that crap. Do we need dependencies? Don't we know that fuse can deadlock only on a limited number of locks in VFS? Regards Oliver