Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754077AbYJTMOx (ORCPT ); Mon, 20 Oct 2008 08:14:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751240AbYJTMOn (ORCPT ); Mon, 20 Oct 2008 08:14:43 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:40686 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752092AbYJTMOm (ORCPT ); Mon, 20 Oct 2008 08:14:42 -0400 Date: Mon, 20 Oct 2008 14:13:39 +0200 From: Ingo Molnar To: Neil Horman Cc: kexec@lists.infradead.org, linux-kernel@vger.kernel.org, vgoyal@redhat.com, hbabu@us.ibm.com, ebiederm@xmission.com, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, akpm@linux-foundation.org, Alexander van Heukelum Subject: Re: [PATCH] kexec: fix hang on i386 when panic occurs while console_sem is held Message-ID: <20081020121339.GE10594@elte.hu> References: <20081017210013.GD23591@hmsreliant.think-freely.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20081017210013.GD23591@hmsreliant.think-freely.org> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00,DNS_FROM_SECURITYSAGE autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] 0.0 DNS_FROM_SECURITYSAGE RBL: Envelope sender in blackholes.securitysage.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1281 Lines: 31 * Neil Horman wrote: > Hey all- > Theres a corner case in 32 bit x86 kdump at the moment. When > the box panics via nmi, we call bust_spinlocks(1) to disable > sensitivity to the console_sem (allowing us to print to the console in > all cases), but we don't call crash_kexec, until after we call > bust_spinlocks(0), which re-enables console_sem sensitivity. The > result is that, if we get an nmi while the console_sem is held and > kdump is configured, and we try to print something to the console > during kdump shutdown (which we often do) we deadlock the box. The > fix is to simply do what 64 bit die_nmi does which is to not call > bust_spinlocks(0) until after we call crash_kexec. Patch below tested > successfully by me: applied to tip/x86/urgent, thanks Neil! > dumpstack_32.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) would be nice to unify this code some more - to create a new arch/x86/kernel/dumpstack.c and fill it in with die_nmi() as a beginning? Ingo -- 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/