From owner-freebsd-fs@FreeBSD.ORG Thu May 28 19:25:49 2009 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 6014D1065678 for ; Thu, 28 May 2009 19:25:49 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from mail.terabit.net.ua (mail.terabit.net.ua [195.137.202.147]) by mx1.freebsd.org (Postfix) with ESMTP id 62E3C8FC16 for ; Thu, 28 May 2009 19:25:48 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from skuns.zoral.com.ua ([91.193.166.194] helo=mail.zoral.com.ua) by mail.terabit.net.ua with esmtps (TLSv1:AES256-SHA:256) (Exim 4.63 (FreeBSD)) (envelope-from ) id 1M9lEX-000NGd-Gs; Thu, 28 May 2009 22:25:45 +0300 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 n4SJPgqR063540 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 28 May 2009 22:25:42 +0300 (EEST) (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 n4SJPgiu003744; Thu, 28 May 2009 22:25:42 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by deviant.kiev.zoral.com.ua (8.14.3/8.14.3/Submit) id n4SJPgSQ003743; Thu, 28 May 2009 22:25:42 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: deviant.kiev.zoral.com.ua: kostik set sender to kostikbel@gmail.com using -f Date: Thu, 28 May 2009 22:25:42 +0300 From: Kostik Belousov To: Jaakko Heinonen Message-ID: <20090528192542.GB1927@deviant.kiev.zoral.com.ua> References: <20090527150258.GA3666@a91-153-125-115.elisa-laajakaista.fi> <20090527153543.GK1927@deviant.kiev.zoral.com.ua> <20090528172943.GA3859@a91-153-125-115.elisa-laajakaista.fi> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="p4lCLMlDzlgb3GqX" Content-Disposition: inline In-Reply-To: <20090528172943.GA3859@a91-153-125-115.elisa-laajakaista.fi> User-Agent: Mutt/1.4.2.3i X-Virus-Scanned: clamav-milter 0.95.1 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 X-Virus-Scanned: mail.terabit.net.ua 1M9lEX-000NGd-Gs 4cbb66d66d45541730408af5df625334 X-Terabit: YES Cc: freebsd-fs@freebsd.org Subject: Re: VOP_WRITE & read-only file system X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 28 May 2009 19:25:49 -0000 --p4lCLMlDzlgb3GqX Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, May 28, 2009 at 08:29:43PM +0300, Jaakko Heinonen wrote: >=20 > Hi, >=20 > On 2009-05-27, Kostik Belousov wrote: > > > 1) mmap(2) > > > - mmap(2) a file > > > - close(2) the file handle > > > - remount file-system as read-only > > > - modify mapped memory >=20 > > Yes, the issue is there. Real cause for the problem is that mmap() does > > not increment v_writecnt of the vnode that backs shared writable mappin= gs. > >=20 > > I have a patch that fixes this, see > > http://people.freebsd.org/~kib/misc/vm_map_delete.3.patch >=20 > The patch seems to have a problem with forced remount or unmount. After > a forced remount to read-only munmap(2) crashes in _vm_map_unlock() > due to NULL vp. >=20 > #12 0xc08f0cb3 in _vn_lock (vp=3D0x0, flags=3D525312,=20 > file=3D0xc0c55e8f "/home/jaakko/src/head/sys/vm/vm_map.c", line=3D494) > at vnode_if.h:830 > #13 0xc0a8cb4f in _vm_map_unlock (map=3D0xc634f000, process_freelist=3D1,= =20 > file=3D0xc0c56902 "/home/jaakko/src/head/sys/vm/vm_mmap.c", line=3D59= 7) > at /home/jaakko/src/head/sys/vm/vm_map.c:494 > #14 0xc0a91d98 in munmap (td=3D0xc5a996c0, uap=3D0xf480ecf8) > at /home/jaakko/src/head/sys/vm/vm_mmap.c:597 > #15 0xc0b637b3 in syscall (frame=3D0xf480ed38) > at /home/jaakko/src/head/sys/i386/i386/trap.c:1073 > #16 0xc0b46a10 in Xint0x80_syscall () > at /home/jaakko/src/head/sys/i386/i386/exception.s:261 I expect that http://people.freebsd.org/~kib/misc/vm_map_delete.4.patch fix the issue. --p4lCLMlDzlgb3GqX Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (FreeBSD) iEYEARECAAYFAkoe5TUACgkQC3+MBN1Mb4g6DQCeOBxmZ/zOeCtzdoApYGyTcSmM /N4AoLAfi4Sf1+CUZ7zDgLsaG2DvzNzC =MMtG -----END PGP SIGNATURE----- --p4lCLMlDzlgb3GqX--