From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754052AbXD1TJL (ORCPT ); Sat, 28 Apr 2007 15:09:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754090AbXD1TJK (ORCPT ); Sat, 28 Apr 2007 15:09:10 -0400 Received: from warden-p.diginsite.com ([208.29.163.248]:35935 "HELO warden.diginsite.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with SMTP id S1754052AbXD1TJJ (ORCPT ); Sat, 28 Apr 2007 15:09:09 -0400 Date: Sat, 28 Apr 2007 11:32:52 -0700 (PDT) From: David Lang X-X-Sender: dlang@dlang.diginsite.com To: Pavel Machek cc: "Rafael J. Wysocki" , Linus Torvalds , Nigel Cunningham , Pekka J Enberg , LKML , Oleg Nesterov Subject: Re: Back to the future. In-Reply-To: <20070428085000.GA3293@elf.ucw.cz> Message-ID: References: <1177567481.5025.211.camel@nigel.suspend2.net> <200704280300.22604.rjw@sisk.pl> <200704280344.49674.rjw@sisk.pl> <20070428085000.GA3293@elf.ucw.cz> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 28 Apr 2007, Pavel Machek wrote: >> >> We freeze user space processes for the reasons that you have quoted above. >> >> Why we freeze kernel threads in there too is a good question, but not for me to >> answer. I don't know. Pavel should know, I think. > > We do not want kernel threads running: > > a) they may hold some locks and deadlock suspend > > b) they may do some writes to disk, leading to corruption > > We could solve a) by carefully auditing suspend lock usage to make > sure deadlocks are impossible even with kernel threads running. remember that we are doing suspend-to-disk, after we do the snapshot we will be doing a shutdown. that should simplify the locking issues David Lang