From owner-freebsd-current  Thu Mar  1 18:35:52 2001
Delivered-To: freebsd-current@freebsd.org
Received: from cr66388-a.rchrd1.on.wave.home.com (cr66388-a.rchrd1.on.wave.home.com [24.114.165.24])
	by hub.freebsd.org (Postfix) with ESMTP id 0FE2B37B718
	for <current@FreeBSD.ORG>; Thu,  1 Mar 2001 18:35:49 -0800 (PST)
	(envelope-from jburkholder0829@home.com)
Received: from cr66388-a.rchrd1.on.wave.home.c (localhost [127.0.0.1])
	by cr66388-a.rchrd1.on.wave.home.com (Postfix) with ESMTP
	id 4F733BACC; Thu,  1 Mar 2001 21:35:48 -0500 (EST)
X-Mailer: exmh version 2.3.1 01/18/2001 with nmh-1.0.4
To: Kris Kennaway <kris@obsecurity.org>
Cc: current@FreeBSD.ORG
Subject: Re: Scheduler panic 
In-Reply-To: Message from Jake Burkholder <jburkholder0829@home.com> 
   of "Mon, 26 Feb 2001 09:25:01 EST." <20010226142501.7D1A5BACB@cr66388-a.rchrd1.on.wave.home.com> 
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Date: Thu, 01 Mar 2001 21:35:47 -0500
From: Jake Burkholder <jburkholder0829@home.com>
Message-Id: <20010302023548.4F733BACC@cr66388-a.rchrd1.on.wave.home.com>
Sender: owner-freebsd-current@FreeBSD.ORG
Precedence: bulk
X-Loop: FreeBSD.ORG

> > On Sun, Feb 25, 2001 at 10:29:42PM -0800, Kris Kennaway wrote:
> > > This is on a UP system.
> > 
> > Had another one of these, under the same conditions.  Both times I was
> > running more(1) on a stdin stream which was generated by a "find |
> > grep | more" operation, and I suspended the process with ^Z,
> > triggering the panic.  Perhaps this will help in tracking down the
> > root cause.
> 
> I'm pretty sure I know what this is; I'll work up a patch tonight.
> 

Sorry this is taking so long.  Its turned out to be a little more
complex to fix properly than I originally thought.  We're going to
have to change the way one of the fields of struct proc (p_pptr)
is locked.  The problem is that a process is getting preempted
when its not SRUN, which should be protected by the scheduler
lock so that the preemption can't occur.

This is the best workaround I can think of:

Index: kern/kern_intr.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/kern_intr.c,v
retrieving revision 1.47
diff -u -r1.47 kern_intr.c
--- kern/kern_intr.c    2001/02/28 02:53:43     1.47
+++ kern/kern_intr.c    2001/03/02 02:28:08
@@ -366,7 +366,7 @@
         */
        ithread->it_need = 1;
        mtx_lock_spin(&sched_lock);
-       if (p->p_stat == SWAIT) {
+       if (p->p_stat == SWAIT && curproc->p_stat == SRUN) {
                CTR1(KTR_INTR, __func__ ": setrunqueue %d", p->p_pid);
                p->p_stat = SRUN;
                setrunqueue(p);

Jake


To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-current" in the body of the message