From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759383AbXGEKDL (ORCPT ); Thu, 5 Jul 2007 06:03:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754278AbXGEKDA (ORCPT ); Thu, 5 Jul 2007 06:03:00 -0400 Received: from smtp-out001.kontent.com ([81.88.40.215]:46197 "EHLO smtp-out.kontent.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754191AbXGEKDA (ORCPT ); Thu, 5 Jul 2007 06:03:00 -0400 From: Oliver Neukum To: Miklos Szeredi Subject: Re: [linux-pm] Re: [PATCH] Remove process freezer from suspend to RAM pathway Date: Thu, 5 Jul 2007 12:02:58 +0200 User-Agent: KMail/1.9.7 Cc: paulus@samba.org, stern@rowland.harvard.edu, johannes@sipsolutions.net, rjw@sisk.pl, linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org, pavel@ucw.cz, mjg59@srcf.ucam.org, benh@kernel.crashing.org References: <18059.10554.955290.148535@cargo.ozlabs.ibm.com> <200707051048.46202.oliver@neukum.org> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200707051202.59375.oliver@neukum.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Am Donnerstag, 5. Juli 2007 schrieb Miklos Szeredi: > > > And teach VFS to block suspension, while waiting on a mutex held by > > > another process performing a fuse operation. > > > > > > I can already hear the beautiful praise from Al Viro at the sight of > > > that ;) > > > > There is that. > > > > OK, bite the bullet. Tasks involved in fuse are special. Give them a flag > > and teach the freezer to put them on ice only after all other task are > > frozen. In a way they are kernel, there's no use denying that. > > And flag every other process, that the flagged process is > communicating with? How are you proposing to do that? > > Quoting Paul: > > "1. The freezer cannot be guaranteed deadlock-free without constructing > a dependency graph between tasks (both user and kernel), which is > virtually impossible since the dependencies are not externally > observable." A deadlock requires that the circular wait is uninterruptible. Normal IPC isn't. What are you doing in the userland portions of fuse? Some kind of IPC with other tasks? There is a limit to which you can push kernel functionality into user space. Regards Oliver