From owner-freebsd-current@FreeBSD.ORG Mon Feb 8 15:08:34 2010 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 6741C106568F; Mon, 8 Feb 2010 15:08:34 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from mail.zoral.com.ua (mx0.zoral.com.ua [91.193.166.200]) by mx1.freebsd.org (Postfix) with ESMTP id E9CC48FC12; Mon, 8 Feb 2010 15:08:33 +0000 (UTC) Received: from deviant.kiev.zoral.com.ua (root@deviant.kiev.zoral.com.ua [10.1.1.148]) by mail.zoral.com.ua (8.14.2/8.14.2) with ESMTP id o18F8Ic7015017 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Mon, 8 Feb 2010 17:08:18 +0200 (EET) (envelope-from kostikbel@gmail.com) Received: from deviant.kiev.zoral.com.ua (kostik@localhost [127.0.0.1]) by deviant.kiev.zoral.com.ua (8.14.3/8.14.3) with ESMTP id o18F8I9W073021; Mon, 8 Feb 2010 17:08:18 +0200 (EET) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by deviant.kiev.zoral.com.ua (8.14.3/8.14.3/Submit) id o18F8IsS073020; Mon, 8 Feb 2010 17:08:18 +0200 (EET) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: deviant.kiev.zoral.com.ua: kostik set sender to kostikbel@gmail.com using -f Date: Mon, 8 Feb 2010 17:08:18 +0200 From: Kostik Belousov To: Attilio Rao Message-ID: <20100208150818.GL9991@deviant.kiev.zoral.com.ua> References: <20100207160031.GA27434@muon.cran.org.uk> <201002080900.44745.jhb@freebsd.org> <20100208145354.GJ9991@deviant.kiev.zoral.com.ua> <3bbf2fe11002080701u35a3e419ke562735f4f00ce97@mail.gmail.com> <3bbf2fe11002080706k11275a9evbf8a7fa1b14b447f@mail.gmail.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="Jbyekxk18hnEXT0m" Content-Disposition: inline In-Reply-To: <3bbf2fe11002080706k11275a9evbf8a7fa1b14b447f@mail.gmail.com> User-Agent: Mutt/1.4.2.3i X-Virus-Scanned: clamav-milter 0.95.2 at skuns.kiev.zoral.com.ua X-Virus-Status: Clean X-Spam-Status: No, score=-4.4 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 autolearn=ham version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on skuns.kiev.zoral.com.ua Cc: bzeeb+freebsd+lor@zabbadoz.net, Bruce Cran , freebsd-current@freebsd.org Subject: Re: LOR: vfs_mount.c (ufs) / msdosfs_vfsops.c (devfs) X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 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: Mon, 08 Feb 2010 15:08:34 -0000 --Jbyekxk18hnEXT0m Content-Type: text/plain; charset=koi8-r Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Feb 08, 2010 at 04:06:56PM +0100, Attilio Rao wrote: > 2010/2/8 Attilio Rao : > > 2010/2/8 Kostik Belousov : > >> On Mon, Feb 08, 2010 at 09:00:44AM -0500, John Baldwin wrote: > >>> On Sunday 07 February 2010 11:00:32 am Bruce Cran wrote: > >>> > Running -CURRENT from today, I unmounted the msdosfs filesystem on = my > >>> > phone and got the following LOR: > >>> > > >>> > lock order reversal: > >>> > =9A1st 0xffffff00c51279f8 ufs (ufs) @ /usr/src/sys/kern/vfs_mount.c= :1204 > >>> > =9A2nd 0xffffff010b892278 devfs (devfs) @ > >>> > /usr/src/sys/modules/msdosfs/../../fs/msdosfs/msdosfs_vfsops.c:944 > >>> > KDB: stack backtrace: > >>> > db_trace_self_wrapper() at db_trace_self_wrapper+0x2a > >>> > _witness_debugger() at witness_debugger+0x2e > >>> > witness_checkorder() at witness_checkorder+0x81e > >>> > __lockmgr_args() at __lockmgr_args+0xd11 > >>> > vop_stdlock() at vop_stdlock+0x39 > >>> > VOP_LOCK1_APV() VOP_LOCK1_APV+0x9b > >>> > _vn_lock() at _vn_lock+0x47 > >>> > msdosfs_sync() at msdosfs_sync+0x227 > >>> > dounmount() at dounmount+0x2ca > >>> > unmount() at unmount+0x216 > >>> > syscall() at syscall+0x2a2 > >>> > Xfast_syscall() at Xfast_syscall+0xe1 > >>> > --- syscall (22, FreeBSD ELF64, unmount), rip =3D 0x8006a1e3c, rsp = =3D > >>> > 0x7fffffffe3a8, rbp =3D 0x800c08010 --- > >>> > >>> This is due to holding a lock on the coveredvp vnode for most of unmo= unt(2). > >>> Probably it should not be held for all of that. =9APerhaps it is safe= to just > >>> keep the vnode referenced instead, or could the handling for coveredv= p just > >>> move to the end of the function where it is now vput? > >> > >> Among other things, holding vnode lock on covered vnode prevents paral= lel > >> unmounts of the same mount point. > > > > Uhm, I think that this should be hanlded by MNTK_UNMOUNT already (and > > thus stopping forced unmounts too). >=20 > In other words probabilly keeping coveredvnode held until MNTK_UNMOUNT > and then refcounting it should be fine. Actually, the coveredvp then might be reclaimed ? Failed unmount then cannot recover. --Jbyekxk18hnEXT0m Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (FreeBSD) iEYEARECAAYFAktwKOIACgkQC3+MBN1Mb4gN8ACfbyEy0RlFkxwuUEhLTVLcLB8W 6WYAn2amrTTHMvBTD2Gd1YD21OnqwDsN =tT1w -----END PGP SIGNATURE----- --Jbyekxk18hnEXT0m--