From owner-freebsd-stable@FreeBSD.ORG Wed Feb 25 14:36:12 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 B251F106564A for ; Wed, 25 Feb 2009 14:36:12 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from cyrus.watson.org (cyrus.watson.org [65.122.17.42]) by mx1.freebsd.org (Postfix) with ESMTP id 821738FC0A for ; Wed, 25 Feb 2009 14:36:12 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from server.baldwin.cx (pool-98-109-39-197.nwrknj.fios.verizon.net [98.109.39.197]) by cyrus.watson.org (Postfix) with ESMTPSA id DEB3C46B09; Wed, 25 Feb 2009 09:36:11 -0500 (EST) Received: from localhost (john@localhost [127.0.0.1]) (authenticated bits=0) by server.baldwin.cx (8.14.3/8.14.3) with ESMTP id n1PEa59N033379; Wed, 25 Feb 2009 09:36:05 -0500 (EST) (envelope-from jhb@freebsd.org) From: John Baldwin To: freebsd-stable@freebsd.org Date: Wed, 25 Feb 2009 09:15:57 -0500 User-Agent: KMail/1.9.7 References: <49A46AB4.3080003@palisadesys.com> In-Reply-To: <49A46AB4.3080003@palisadesys.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200902250915.57562.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH authentication, not delayed by milter-greylist-2.0.2 (server.baldwin.cx [127.0.0.1]); Wed, 25 Feb 2009 09:36:05 -0500 (EST) X-Virus-Scanned: ClamAV 0.94.2/9047/Wed Feb 25 05:59:41 2009 on server.baldwin.cx X-Virus-Status: Clean X-Spam-Status: No, score=-4.4 required=4.2 tests=ALL_TRUSTED,AWL,BAYES_00 autolearn=ham version=3.1.3 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on server.baldwin.cx Cc: Guy Helmer 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 14:36:13 -0000 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. -- John Baldwin