From owner-freebsd-current@FreeBSD.ORG Thu Dec 16 22:33:54 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 D508016A4CE for ; Thu, 16 Dec 2004 22:33:54 +0000 (GMT) Received: from mail4.speakeasy.net (mail4.speakeasy.net [216.254.0.204]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5E66E43D5E for ; Thu, 16 Dec 2004 22:33:52 +0000 (GMT) (envelope-from jhb@FreeBSD.org) Received: (qmail 6127 invoked from network); 16 Dec 2004 22:33:52 -0000 Received: from dsl027-160-063.atl1.dsl.speakeasy.net (HELO server.baldwin.cx) ([216.27.160.63]) (envelope-sender ) encrypted SMTP for ; 16 Dec 2004 22:33:51 -0000 Received: from [10.50.41.243] (gw1.twc.weather.com [216.133.140.1]) (authenticated bits=0) by server.baldwin.cx (8.12.11/8.12.11) with ESMTP id iBGMXjjd012891; Thu, 16 Dec 2004 17:33:46 -0500 (EST) (envelope-from jhb@FreeBSD.org) From: John Baldwin To: Peter Holm Date: Thu, 16 Dec 2004 16:45:05 -0500 User-Agent: KMail/1.6.2 References: <20041112123343.GA12048@peter.osted.lan> <200412161521.44026.jhb@FreeBSD.org> <20041216213157.GA41605@peter.osted.lan> In-Reply-To: <20041216213157.GA41605@peter.osted.lan> MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <200412161645.05379.jhb@FreeBSD.org> X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on server.baldwin.cx cc: jroberson@chesapeake.net cc: freebsd-current@FreeBSD.org cc: bmilekic@FreeBSD.org cc: jeffr@FreeBSD.org 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 22:33:55 -0000 On Thursday 16 December 2004 04:31 pm, Peter Holm wrote: > 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 was referring to my earlier patch that breaks out of the loop if M_WAITOK is set so that it shouldn't spin at all in that case. Do you have that hackish patch already applied and it's spinning anyway? -- John Baldwin <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org