Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030186AbWARIZh (ORCPT ); Wed, 18 Jan 2006 03:25:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030188AbWARIZh (ORCPT ); Wed, 18 Jan 2006 03:25:37 -0500 Received: from smtp.osdl.org ([65.172.181.4]:42912 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1030186AbWARIZg (ORCPT ); Wed, 18 Jan 2006 03:25:36 -0500 Date: Wed, 18 Jan 2006 00:24:59 -0800 From: Andrew Morton To: Ingo Molnar Cc: ntl@pobox.com, anton@au1.ibm.com, linux-kernel@vger.kernel.org, michael@ellerman.id.au, linuxppc64-dev@ozlabs.org, serue@us.ibm.com, paulus@au1.ibm.com, torvalds@osdl.org Subject: Re: 2.6.15-mm4 failure on power5 Message-Id: <20060118002459.3bc8f75a.akpm@osdl.org> In-Reply-To: <20060118080828.GA2324@elte.hu> References: <20060116063530.GB23399@sergelap.austin.ibm.com> <200601180032.46867.michael@ellerman.id.au> <20060117140050.GA13188@elte.hu> <200601181119.39872.michael@ellerman.id.au> <20060118033239.GA621@cs.umn.edu> <20060118063732.GA21003@elte.hu> <20060117225304.4b6dd045.akpm@osdl.org> <20060118072815.GR2846@localhost.localdomain> <20060117233734.506c2f2e.akpm@osdl.org> <20060118080828.GA2324@elte.hu> X-Mailer: Sylpheed version 1.0.4 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1659 Lines: 39 Ingo Molnar wrote: > > > * Andrew Morton wrote: > > > > Yes, which would be why this code never triggered a warning when > > > cpucontrol was a semaphore. > > > > Yup. Perhaps a sane fix which preserves the unpleasant semantics is > > to do irqsave in the mutex debug code. > > i'd much rather remove that ugly hack from __might_sleep(). How many > other bugs does it hide? Gee, it was 2.6.0-test9. I don't remember, but I do recall the problems were really really nasty, and what's the point? We're only running one thread on one CPU at that time, so none of these things _will_ sleep. > Does it hide bugs that dont normally trigger > during bootups on real hardware, but which could trigger on e.g. UML or > on Xen? I really think such ugly workarounds are not justified, if other > arches can get their act together. Would you make such an exception for > other arches too, like ARM? Don't care really, as long as a) the problems don't hit -mm or mainline and b) someone else fixes them. Yes, it'd be nice to fix these things, and we might even find real bugs. Perhaps things are better now, but I suspect it's a can of worms. > an irqsave in the mutex debug code will uglify the kernel/mutex.c code - > i'd have to add extra "unsigned long flags" lines. [It will also slow > down the debug code a bit - an extra PUSHF has to be done.] Small cost, really... - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/