From owner-freebsd-stable@FreeBSD.ORG Wed Feb 25 15:02:20 2009 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 32A96106567A for ; Wed, 25 Feb 2009 15:02:20 +0000 (UTC) (envelope-from ghelmer@palisadesys.com) Received: from cetus.palisadesys.com (cetus.palisadesys.com [205.237.115.21]) by mx1.freebsd.org (Postfix) with ESMTP id 055D28FC14 for ; Wed, 25 Feb 2009 15:02:19 +0000 (UTC) (envelope-from ghelmer@palisadesys.com) Received: from cancer.palisadesys.com (serverwatch [172.16.1.98]) by cetus.palisadesys.com (8.14.3/8.14.3) with ESMTP id n1PF2JOC081656; Wed, 25 Feb 2009 09:02:19 -0600 (CST) (envelope-from ghelmer@palisadesys.com) Received: from [172.16.2.242] (cetus.palisadesys.com [205.237.115.21]) (authenticated bits=0) by cancer.palisadesys.com (8.14.2/8.14.2) with ESMTP id n1PF2JFf078732; Wed, 25 Feb 2009 09:02:19 -0600 (CST) (envelope-from ghelmer@palisadesys.com) Message-ID: <49A55D78.1070604@palisadesys.com> Date: Wed, 25 Feb 2009 09:02:16 -0600 From: Guy Helmer User-Agent: Thunderbird 2.0.0.19 (Windows/20081209) MIME-Version: 1.0 To: John Baldwin References: <49A46AB4.3080003@palisadesys.com> <200902250915.57562.jhb@freebsd.org> In-Reply-To: <200902250915.57562.jhb@freebsd.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH authentication, not delayed by milter-greylist-3.0 (cancer.palisadesys.com [205.237.115.20]); Wed, 25 Feb 2009 09:02:19 -0600 (CST) X-Palisade-MailScanner-Information: Please contact the ISP for more information X-Palisade-MailScanner: Found to be clean X-Palisade-MailScanner-SpamCheck: not spam (whitelisted), SpamAssassin (not cached, score=-3.799, required 6, ALL_TRUSTED -1.80, BAYES_00 -2.60, J_CHICKENPOX_48 0.60) X-Palisade-MailScanner-From: ghelmer@palisadesys.com Cc: freebsd-stable@freebsd.org Subject: Re: 7.1 hangs in cache_lookup mutex? X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 25 Feb 2009 15:02:20 -0000 John Baldwin wrote: > On Tuesday 24 February 2009 4:46:28 pm Guy Helmer wrote: > >> I think I may have found a clue regarding some of the hangs I'm seeing >> on FreeBSD 7.1. >> I have a program (kvoop), compiled under FreeBSD 6 and using >> compatibility libraries under FreeBSD 7, that seems to be consistently >> involved during these hangs. This time, I noticed that many processes >> are stopped, waiting on the ufs lock. I can't tell for certain, but I >> assume this kvoop process 33203 is blocking the other processes. The >> kvoop process looks to me like it is waiting for a mutex, but nothing >> shows up being deadlocked. Am I on the right track? Is there something >> else I should be looking for? >> >> (kgdb) proc 33203 >> [Switching to thread 129 (Thread 100241)]#0 sched_switch ( >> td=0xffffff0019109a50, newtd=0x0, flags=1) >> at ../../../kern/sched_ule.c:1944 >> 1944 cpuid = PCPU_GET(cpuid); >> (kgdb) where >> #0 sched_switch (td=0xffffff0019109a50, newtd=0x0, flags=1) >> at ../../../kern/sched_ule.c:1944 >> #1 0xffffffff803a573b in mi_switch (flags=1, newtd=0x0) >> at ../../../kern/kern_synch.c:440 >> #2 0xffffffff803d1214 in turnstile_wait (ts=Variable "ts" is not available. >> ) >> at ../../../kern/subr_turnstile.c:748 >> #3 0xffffffff80392db0 in _mtx_lock_sleep (m=0xffffffff8083c220, >> tid=18446742974618442320, opts=Variable "opts" is not available. >> ) at ../../../kern/kern_mutex.c:420 >> #4 0xffffffff80392ea6 in _mtx_lock_flags (m=0xffffffff8083c220, opts=0, >> file=0xffffffff805bd438 "../../../kern/vfs_cache.c", line=327) >> at ../../../kern/kern_mutex.c:186 >> #5 0xffffffff80403bc6 in cache_lookup (dvp=0xffffff00013e0dc8, >> vpp=0xffffffffa2d93a18, cnp=0xffffffffa2d93a40) >> at ../../../kern/vfs_cache.c:327 >> #6 0xffffffff80404093 in vfs_cache_lookup (ap=Variable "ap" is not >> available. >> ) >> at ../../../kern/vfs_cache.c:674 >> #7 0xffffffff805628a0 in VOP_LOOKUP_APV (vop=0xffffffff8076e440, >> a=0xffffffffa2d936b0) at vnode_if.c:99 >> #8 0xffffffff80409afd in lookup (ndp=0xffffffffa2d939f0) at vnode_if.h:57 >> #9 0xffffffff8040a824 in namei (ndp=0xffffffffa2d939f0) >> at ../../../kern/vfs_lookup.c:219 >> #10 0xffffffff8041dc4f in vn_open_cred (ndp=0xffffffffa2d939f0, >> flagp=0xffffffffa2d9393c, cmode=0, cred=0xffffff0001588600, >> fp=0xffffff0001964200) at ../../../kern/vfs_vnops.c:188 >> #11 0xffffffff8041ccc7 in kern_open (td=0xffffff0019109a50, >> path=0xffffac30
, pathseg=Variable >> "pathseg" is not available. >> ) >> at ../../../kern/vfs_syscalls.c:1032 >> #12 0xffffffff80544660 in ia32_syscall (frame=0xffffffffa2d93c80) >> at ../../../amd64/ia32/ia32_syscall.c:182 >> #13 0xffffffff805014d0 in Xint0x80_syscall () at ia32_exception.S:65 >> #14 0x0000000028284037 in ?? () >> >> (kgdb) frame 4 >> #4 0xffffffff80392ea6 in _mtx_lock_flags (m=0xffffffff8083c220, opts=0, >> file=0xffffffff805bd438 "../../../kern/vfs_cache.c", line=327) >> at ../../../kern/kern_mutex.c:186 >> 186 _get_sleep_lock(m, curthread, opts, file, line); >> (kgdb) list >> 181 ("mtx_lock() of spin mutex %s @ %s:%d", >> m->lock_object.lo_name, >> 182 file, line)); >> 183 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER >> | LOP_EXCLUSIVE, >> 184 file, line); >> 185 >> 186 _get_sleep_lock(m, curthread, opts, file, line); >> 187 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, >> m->mtx_recurse, file, >> 188 line); >> 189 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, >> file, line); >> 190 curthread->td_locks++; >> >> (kgdb) print *m >> $2 = {lock_object = {lo_name = 0xffffffff805bd5d2 "Name Cache", >> lo_type = 0xffffffff805bd5d2 "Name Cache", lo_flags = 16973824, >> lo_witness_data = {lod_list = {stqe_next = 0xffffffff807cd600}, >> lod_witness = 0xffffffff807cd600}}, mtx_lock = 4, mtx_recurse = 0} >> > > Is this from a coredump or while the system is live? mtx_lock = 4 indicates > the mutex is unlocked, so there shouldn't be any threads waiting on it. > > That was from running kgdb on a vmcore file. Would the state of the mutex be different than if I was running kgdb on a live kernel? Thanks, Guy