From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Date: Thu, 28 Feb 2008 19:12:14 +0000 Subject: Re: 2.6.25-rc2-mm1 - boot hangs on ia64 Message-Id: <20080228191214.GA17872@elte.hu> List-Id: References: <20080227103831.423F.KOSAKI.MOTOHIRO@jp.fujitsu.com> <20080227071118.GA4638@elte.hu> <20080228192509.BDCF.KOSAKI.MOTOHIRO@jp.fujitsu.com> <20080228115041.GA22082@elte.hu> <20080228101343.1b9548e6.akpm@linux-foundation.org> In-Reply-To: <20080228101343.1b9548e6.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Andrew Morton Cc: KOSAKI Motohiro , Steven Rostedt , Lee Schermerhorn , linux-ia64 , linux-kernel , Tony Luck , Ingo Molnar , Bob Picco , Eric Whitney * Andrew Morton wrote: > On Thu, 28 Feb 2008 12:50:41 +0100 Ingo Molnar wrote: > > > @@ -1000,7 +1001,7 @@ void release_console_sem(void) > > * If we try to wake up klogd while printing with the runqueue lock > > * held, this will deadlock. > > */ > > - if (wake_klogd && !runqueue_is_locked()) > > + if (wake_klogd) > > wake_up_klogd(); > > } > > I don't think we shoudl have added that hack in the first place. It > solves a problem which about three developers hit four times in five > years but it has made kernel logging less reliable for everyone. well, the problem was ia64, not a problem on x86 or other platforms. The problem here is ia64 not setting up percpu data structures soon enough. It has blown up in the past in other areas, and it will likely blow up in the future in other areas as well. It's just not robust to have init dependencies on such basic data structures like percpu areas like that. Ingo From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762468AbYB1TNr (ORCPT ); Thu, 28 Feb 2008 14:13:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762092AbYB1TMk (ORCPT ); Thu, 28 Feb 2008 14:12:40 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:43622 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761230AbYB1TMi (ORCPT ); Thu, 28 Feb 2008 14:12:38 -0500 Date: Thu, 28 Feb 2008 20:12:14 +0100 From: Ingo Molnar To: Andrew Morton Cc: KOSAKI Motohiro , Steven Rostedt , Lee Schermerhorn , linux-ia64 , linux-kernel , Tony Luck , Ingo Molnar , Bob Picco , Eric Whitney Subject: Re: 2.6.25-rc2-mm1 - boot hangs on ia64 Message-ID: <20080228191214.GA17872@elte.hu> References: <20080227103831.423F.KOSAKI.MOTOHIRO@jp.fujitsu.com> <20080227071118.GA4638@elte.hu> <20080228192509.BDCF.KOSAKI.MOTOHIRO@jp.fujitsu.com> <20080228115041.GA22082@elte.hu> <20080228101343.1b9548e6.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080228101343.1b9548e6.akpm@linux-foundation.org> User-Agent: Mutt/1.5.17 (2007-11-01) 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 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Andrew Morton wrote: > On Thu, 28 Feb 2008 12:50:41 +0100 Ingo Molnar wrote: > > > @@ -1000,7 +1001,7 @@ void release_console_sem(void) > > * If we try to wake up klogd while printing with the runqueue lock > > * held, this will deadlock. > > */ > > - if (wake_klogd && !runqueue_is_locked()) > > + if (wake_klogd) > > wake_up_klogd(); > > } > > I don't think we shoudl have added that hack in the first place. It > solves a problem which about three developers hit four times in five > years but it has made kernel logging less reliable for everyone. well, the problem was ia64, not a problem on x86 or other platforms. The problem here is ia64 not setting up percpu data structures soon enough. It has blown up in the past in other areas, and it will likely blow up in the future in other areas as well. It's just not robust to have init dependencies on such basic data structures like percpu areas like that. Ingo