From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934697AbXGZTOZ (ORCPT ); Thu, 26 Jul 2007 15:14:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761239AbXGZTOQ (ORCPT ); Thu, 26 Jul 2007 15:14:16 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:37898 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761013AbXGZTOP (ORCPT ); Thu, 26 Jul 2007 15:14:15 -0400 From: "Rafael J. Wysocki" To: Linus Torvalds Subject: Re: [2.6.23-rc1 REGRESSION] CPU hotplug totally broken on HPC nx6325 (x86_64) Date: Thu, 26 Jul 2007 21:22:49 +0200 User-Agent: KMail/1.9.5 Cc: Andi Kleen , LKML , Andrew Morton , Pavel Machek , Michal Piotrowski References: <200707261440.50649.rjw@sisk.pl> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200707262122.50517.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, 26 July 2007 18:43, Linus Torvalds wrote: > > On Thu, 26 Jul 2007, Rafael J. Wysocki wrote: > > > > On my Turion64-based HPC nx6325 with the 2.6.23-rc1 x86_64 kernel doing > > > > # echo 0 > /sys/devices/system/cpu/cpu1/online > > > > causes the system to crash in a spectacular fashion (call traces going > > continuously on the console, no reaction to anything except for the power > > button). For this reason, suspend and hibernation don't work as well. > > Yeah, I really shouldn't have applied that patch. I didn't notice that it > not only cleaned up the direct memcpy's, it also re-introduced the damn > broken code that we fixed once already. > > Dammit, that read-only debug support IS NOT WORTH THIS CRAP. > > I absolutely *detest* it when "debugging features" end up being the thing > that causes crashes. I think it shows a total lack of taste and > understanding, and I'm totally tired of it. This has happened too many > times. > > Andi: please don't send this patch *ever* again. If a patch that is > supposed to help debugging just causes problems, that patch should be > thrown away FOREVER. > > Andrew - on that same note: please throw away the dwarf traceback crap > from your tree that Andi is still apparently pushing. Exact same issue. > > Debugging "helper" code that has historically only caused problems. We > could equally well just enable frame pointers for debugging and add the > trivial code to follow that instead, and it would work (the way it has > worked on x86 basically forever). > > Rafael, does reverting just this part (and leaving the "text_poke()" > cleanups) work for you? Yes, it does, with the appended fix on top. :-) Greetings, Rafael --- arch/i386/kernel/alternative.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: linux-2.6.23-rc1/arch/i386/kernel/alternative.c =================================================================== --- linux-2.6.23-rc1.orig/arch/i386/kernel/alternative.c +++ linux-2.6.23-rc1/arch/i386/kernel/alternative.c @@ -432,7 +432,7 @@ void __init alternative_instructions(voi */ void __kprobes text_poke(void *oaddr, unsigned char *opcode, int len) { - memcpy(addr, opcode, len); + memcpy(oaddr, opcode, len); sync_core(); /* Not strictly needed, but can speed CPU recovery up. Ignore cross cacheline case. */