From owner-freebsd-current@FreeBSD.ORG  Wed Dec  3 10:36:39 2003
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
Delivered-To: freebsd-current@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP
	id BB0D616A4CE; Wed,  3 Dec 2003 10:36:39 -0800 (PST)
Received: from park.rambler.ru (park.rambler.ru [81.19.64.101])
	by mx1.FreeBSD.org (Postfix) with ESMTP
	id CEBA043FDF; Wed,  3 Dec 2003 10:36:37 -0800 (PST)
	(envelope-from is@rambler-co.ru)
Received: from is (is.park.rambler.ru [81.19.64.102])
	by park.rambler.ru (8.12.6/8.12.6) with ESMTP id hB3IaaWU014360;
	Wed, 3 Dec 2003 21:36:36 +0300 (MSK)
	(envelope-from is@rambler-co.ru)
Date: Wed, 3 Dec 2003 21:36:36 +0300 (MSK)
From: Igor Sysoev <is@rambler-co.ru>
X-Sender: is@is
To: John Baldwin <jhb@FreeBSD.org>
In-Reply-To: <XFMail.20031203130256.jhb@FreeBSD.org>
Message-ID: <Pine.BSF.4.21.0312032133500.24397-100000@is>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
cc: freebsd-current@FreeBSD.org
Subject: Re: A page fault in subr_turnstile.c:propogate_priority()
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
	<freebsd-current.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 03 Dec 2003 18:36:39 -0000

On Wed, 3 Dec 2003, John Baldwin wrote:

> On 03-Dec-2003 Igor Sysoev wrote:
> > On Wed, 3 Dec 2003, John Baldwin wrote:
> > 
> >> 
> >> On 03-Dec-2003 Igor Sysoev wrote:
> >> > On Wed, 3 Dec 2003, John Baldwin wrote:
> >> > 
> >> >> On 03-Dec-2003 Brian F. Feldman wrote:
> >> >> > Igor Sysoev <is@rambler-co.ru> wrote:
> >> >> >> I'd cvsup'ed 5.1-CURRENT from 2003.11.04.02.02.00 up to
> >> >> >> 2003.11.28.00.00.00 with the turnstile support and it can still
> >> >> >> causes sometimes a page fault in propogate_priority().
> >> >> >> I have core dump and can send debug output.

> Both faults are a trap 12 page fault with a faulting va of 0xe5
> because td1 is NULL in priority propagation.  Try this change to
> get a better cashdump that can be analyzed:
> 
> Index: subr_turnstile.c
> ===================================================================
> RCS file: /usr/cvs/src/sys/kern/subr_turnstile.c,v
> retrieving revision 1.134
> diff -u -r1.134 subr_turnstile.c
> --- subr_turnstile.c    12 Nov 2003 23:48:42 -0000      1.134
> +++ subr_turnstile.c    3 Dec 2003 17:48:02 -0000
> @@ -254,6 +254,7 @@
>                 }
>  
>                 td1 = TAILQ_PREV(td, threadqueue, td_lockq);
> +               MPASS(td1 != NULL);
>                 if (td1->td_priority <= pri) {
>                         mtx_unlock_spin(&tc->tc_lock);
>                         continue;
> 
> Then print 'td' and '*ts' in gdb from the priority_propagation()
> frame and mail the output.

With a patch from http://www.FreeBSD.org/~jhb/patches/turnstile.patch
I can not even rebuild kernel. Can I add MPASS to sources from
2003.11.28.00.00.00 ?


Igor Sysoev
http://sysoev.ru/en/