From owner-freebsd-current@FreeBSD.ORG Thu Dec 16 21:32:01 2004 Return-Path: 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 A3FA116A4D0 for ; Thu, 16 Dec 2004 21:32:01 +0000 (GMT) Received: from relay03.pair.com (relay03.pair.com [209.68.5.17]) by mx1.FreeBSD.org (Postfix) with SMTP id C1BBA43D54 for ; Thu, 16 Dec 2004 21:32:00 +0000 (GMT) (envelope-from pho@holm.cc) Received: (qmail 52283 invoked from network); 16 Dec 2004 21:31:58 -0000 Received: from unknown (HELO peter.osted.lan) (unknown) by unknown with SMTP; 16 Dec 2004 21:31:58 -0000 X-pair-Authenticated: 80.164.63.199 Received: from peter.osted.lan (localhost.osted.lan [127.0.0.1]) by peter.osted.lan (8.13.1/8.13.1) with ESMTP id iBGLVwES041677; Thu, 16 Dec 2004 22:31:58 +0100 (CET) (envelope-from pho@peter.osted.lan) Received: (from pho@localhost) by peter.osted.lan (8.13.1/8.13.1/Submit) id iBGLVvei041676; Thu, 16 Dec 2004 22:31:57 +0100 (CET) (envelope-from pho) Date: Thu, 16 Dec 2004 22:31:57 +0100 From: Peter Holm To: John Baldwin Message-ID: <20041216213157.GA41605@peter.osted.lan> References: <20041112123343.GA12048@peter.osted.lan> <200411191710.19215.jhb@FreeBSD.org> <20041206135934.GA24238@peter.osted.lan> <200412161521.44026.jhb@FreeBSD.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200412161521.44026.jhb@FreeBSD.org> User-Agent: Mutt/1.4.2.1i cc: freebsd-current@FreeBSD.org cc: bmilekic@FreeBSD.org cc: jeffr@FreeBSD.org cc: jroberson@chesapeake.net Subject: Re: Freeze X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 16 Dec 2004 21:32:01 -0000 On Thu, Dec 16, 2004 at 03:21:44PM -0500, John Baldwin wrote: > On Monday 06 December 2004 08:59 am, Peter Holm wrote: > > On Fri, Nov 19, 2004 at 05:10:19PM -0500, John Baldwin wrote: > > > On Friday 19 November 2004 02:59 am, Peter Holm wrote: > > > > On Mon, Nov 15, 2004 at 03:46:15PM -0500, John Baldwin wrote: > > > > > On Friday 12 November 2004 07:33 am, Peter Holm wrote: > > > > > > GENERIC HEAD from Nov 11 08:05 UTC > > > > > > > > > > > > The following stack traces etc. was done before my first > > > > > > cup of coffee, so it's not so informative as it could have been :-( > > > > > > > > > > > > The test box appeared to have been frozen for more than 6 hours, > > > > > > but was pingable. > > > > > > > > > > > > http://www.holm.cc/stress/log/cons86.html > > > > > > > > > > A weak guess is that you have the system in some sort of livelock due > > > > > to fork()? Have you tried running with 'debug.mpsafevm=1' set from > > > > > the loader? > > > > > > > > > > -- > > > > > John Baldwin <>< http://www.FreeBSD.org/~jhb/ > > > > > "Power Users Use the Power to Serve" = http://www.FreeBSD.org > > > > > > > > OK, I've got some more info: > > > > > > > > http://www.holm.cc/stress/log/cons88.html > > > > > > > > Looks like a spin in uma_zone_slab() when slab_zalloc() fails? > > > > > > Yes, I think if you specify M_WAITOK, then that might happen. > > > slab_zalloc() can fail if any of the init functions fail for example, in > > > which case it would loop forever. You can try this hack (though it may > > > very well be wrong) to return failure if that is what is triggering: > > > > > > Index: uma_core.c > > > =================================================================== > > > RCS file: /usr/cvs/src/sys/vm/uma_core.c,v > > > retrieving revision 1.110 > > > diff -u -r1.110 uma_core.c > > > --- uma_core.c 6 Nov 2004 11:43:30 -0000 1.110 > > > +++ uma_core.c 19 Nov 2004 22:08:26 -0000 > > > @@ -1998,6 +1998,10 @@ > > > */ > > > if (flags & M_NOWAIT) > > > flags |= M_NOVM; > > > + > > > + /* XXXHACK */ > > > + if (flags & M_WAITOK) > > > + break; > > > } > > > return (slab); > > > } > > > > > > -- > > > John Baldwin <>< http://www.FreeBSD.org/~jhb/ > > > "Power Users Use the Power to Serve" = http://www.FreeBSD.org > > > > I instrumented the code with this: > > $ cvs diff -u > > cvs diff: Diffing . > > Index: uma_core.c > > =================================================================== > > RCS file: /home/ncvs/src/sys/vm/uma_core.c,v > > retrieving revision 1.110 > > diff -u -r1.110 uma_core.c > > --- uma_core.c 6 Nov 2004 11:43:30 -0000 1.110 > > +++ uma_core.c 6 Dec 2004 13:49:36 -0000 > > @@ -1926,6 +1926,7 @@ > > { > > uma_slab_t slab; > > uma_keg_t keg; > > + int i; > > > > keg = zone->uz_keg; > > > > @@ -1943,7 +1944,8 @@ > > > > slab = NULL; > > > > - for (;;) { > > + for (i = 0;;i++) { > > + KASSERT(i < 10000, ("uma_zone_slab is looping")); > > /* > > * Find a slab with some space. Prefer slabs that are > > partially * used over those that are totally full. This helps to reduce > > > > and now during test of Jeff Roberson's "SMP FFS" patch the assert > > triggered: http://www.holm.cc/stress/log/cons92.html > > Hmm. Does the hack patch above make the hang go away or does it just break > things worse? > How would an assert make a problem go away? It was meant as a tool to figure out the source of the problem; The freeze. I still, rather seldom, see a freeze so would enabling SW_WATCHDOG be a better debugging tool? - Peter