From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757933AbaDWTfy (ORCPT ); Wed, 23 Apr 2014 15:35:54 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:58818 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754614AbaDWTfw (ORCPT ); Wed, 23 Apr 2014 15:35:52 -0400 Date: Wed, 23 Apr 2014 12:35:50 -0700 From: Andrew Morton To: Don Zickus Cc: LKML , x86@kernel.org, davem@davemloft.net, sparclinux@vger.kernel.org, mguzik@redhat.com Subject: Re: [PATCH 0/4 V3] Print traces on softlockup Message-Id: <20140423123550.1818553bcdff3ef058efd3f7@linux-foundation.org> In-Reply-To: <20140423192228.GY8488@redhat.com> References: <1398179848-197479-1-git-send-email-dzickus@redhat.com> <20140422112828.ea511cefa17affb99d9aa97f@linux-foundation.org> <20140423192228.GY8488@redhat.com> X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 23 Apr 2014 15:22:28 -0400 Don Zickus wrote: > On Tue, Apr 22, 2014 at 11:28:28AM -0700, Andrew Morton wrote: > > On Tue, 22 Apr 2014 11:17:24 -0400 Don Zickus wrote: > > > > > Added more patches to handle the 'uniprocessor' panic case by sending NMIs > > > to every cpu but self. Only affects x86, sparc. > > > > > > > Looks OK to me. A couple of things: > > > > - Patches 1-3 should be combined so we don't create bisection holes > > due to x86 and sparc build errors. > > > > - Patch 4 adds stuff which is unusable on uniprocessor, especially > > the presence of /proc/sys/kernel/softlockup_all_cpu_backtrace. We > > already have #ifdef CONFIG_SMP in kern_table, so do more of that? > > Are you suggesting just add CONFIG_SMP to kern_table entry or all the > pieces in kernel/watchdog.c too? I wasn't sure how messy I should make > this patch. Well, don't go nuts and be tasteful. /proc/sys/kernel/softlockup_all_cpu_backtrace should disappear. Look around for existing #ifdef CONFIG_SMP blocks to use. Making sysctl_softlockup_all_cpu_backtrace evaluate to literal zero will cause the compiler to remove unused code without ifdefs. This might require that watchdog_timer_fn:softlockup_all_cpu_backtrace (why does this local exist btw) be declared const - check the compiler output.