From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964820AbWBVTni (ORCPT ); Wed, 22 Feb 2006 14:43:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964824AbWBVTni (ORCPT ); Wed, 22 Feb 2006 14:43:38 -0500 Received: from smtp.osdl.org ([65.172.181.4]:58277 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S964820AbWBVTnh (ORCPT ); Wed, 22 Feb 2006 14:43:37 -0500 Date: Wed, 22 Feb 2006 11:39:33 -0800 (PST) From: Linus Torvalds To: Greg KH cc: Gabor Gombas , "Theodore Ts'o" , Andrew Morton , Kay Sievers , penberg@cs.helsinki.fi, bunk@stusta.de, rml@novell.com, linux-kernel@vger.kernel.org, johnstul@us.ibm.com Subject: Re: 2.6.16-rc4: known regressions In-Reply-To: <20060222191832.GA14638@suse.de> Message-ID: References: <20060221153305.5d0b123f.akpm@osdl.org> <20060222000429.GB12480@vrfy.org> <20060221162104.6b8c35b1.akpm@osdl.org> <20060222112158.GB26268@thunk.org> <20060222154820.GJ16648@ca-server1.us.oracle.com> <20060222162533.GA30316@thunk.org> <20060222173354.GJ14447@boogie.lpds.sztaki.hu> <20060222185923.GL16648@ca-server1.us.oracle.com> <20060222191832.GA14638@suse.de> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 22 Feb 2006, Greg KH wrote: > > RHEL is a very different kernel from mainline (just like SLES is). Have > you looked through their patches to see if they are including something > that causes this behavior? Quite apart from that, we have definitely had issues where pure timing makes a difference - the kernel does the same exact thing, but just switches the order of some driver initialization, so that when /sbin/init starts, some discovery is still on-going. It's _rare_, but it's one kind of bug that the kernel really can't do a lot about. For example, for the longest time we held off from the scheduler running child programs before returning to the parent after a fork(), simply because that triggered a real race condition in "bash". Eventually, we could say "screw it, it's a user-level timing bug", but the point being that sometimes timing changes, and while we _can_ try to keep even timing-related behaviour like that similar, sometimes it just isn't possible. It's quite possible that nothing has really "changed", and that some part of the kernel just finishes more quickly (or slowly), triggering this problem. Linus