Date: Tue, 2 May 2006 17:40:21 GMT From: Kris Kennaway <kris@obsecurity.org> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/96644: crash after mount/umount disturbance: fatal trap 12 Message-ID: <200605021740.k42HeLXY075077@freefall.freebsd.org>
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The following reply was made to PR kern/96644; it has been noted by GNATS. From: Kris Kennaway <kris@obsecurity.org> To: Arne Woerner <arne_woerner@yahoo.com> Cc: freebsd-gnats-submit@FreeBSD.org Subject: Re: kern/96644: crash after mount/umount disturbance: fatal trap 12 Date: Tue, 2 May 2006 13:37:04 -0400 --5/uDoXvLw7AC5HRs Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, May 02, 2006 at 06:38:19AM +0000, Arne Woerner wrote: >=20 > >Number: 96644 > >Category: kern > >Synopsis: crash after mount/umount disturbance: fatal trap 12 > >Confidential: no > >Severity: non-critical > >Priority: low > >Responsible: freebsd-bugs > >State: open > >Quarter: =20 > >Keywords: =20 > >Date-Required: > >Class: sw-bug > >Submitter-Id: current-users > >Arrival-Date: Tue May 02 06:40:13 GMT 2006 > >Closed-Date: > >Last-Modified: > >Originator: Arne Woerner > >Release: R6.0 > >Organization: > >Environment: > FreeBSD neo.riddick.homeunix.org 6.0-RELEASE FreeBSD 6.0-RELEASE #10: > Mon Apr 10 15:10:38 UTC 2006 > aw@neo.riddick.homeunix.org:/usr/src/sys/i386/compile/NEO i386 >=20 > >Description: > Once upon a time I looked through my self made DVDs. When I mounted a DVD > twice at the same mount point and read from that DVD and unmounted the DVD > once and read again from it, the system crashed. >=20 > This is not really bad, since I usually know, what is mounted... > But it might be nicer, if the kernel could cope with such things... > >How-To-Repeat: > cd /opt/tmp > dd if=3D/dev/zero of=3Da bs=3D1m count=3D200 > mdconfig -a -t vnode -f a > newfs /dev/md0 > mount /dev/md0 /mnt > dd if=3D/dev/zero of=3D/mnt/a bs=3D1m count=3D100 > umount /mnt > mount -r /dev/md0 /mnt > mount -r /dev/md0 /mnt > dd if=3D/mnt/a of=3D/dev/null bs=3D1m > umount /mnt > dd if=3D/mnt/a of=3D/dev/null bs=3D1m > *cloink* >=20 > kernel says: > fatal trap 12: page fault while in kernel mode > fault virtual address =3D 0x0 > fault code =3D supervisor read, page not present FYI, usually more details are required when submitting reports of panics, e.g. a full backtrace from kgdb (see the developers handbook chapter on kernel debugging). In this case, it's a known bug that mounting the same filesystem twice as you did can lead to panics. Kris --5/uDoXvLw7AC5HRs Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.3 (FreeBSD) iD8DBQFEV5jAWry0BWjoQKURAiArAKCOzs5ZdPbAQhI56gGDFI+Mp9mlhgCg18g4 wGW5iaOaVjKYMHUOQx4ZJWY= =clJB -----END PGP SIGNATURE----- --5/uDoXvLw7AC5HRs--
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