Date: Mon, 20 May 2013 10:34:26 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Antoine Brodin <antoine@FreeBSD.org> Cc: freebsd-fs@freebsd.org, pho@freebsd.org Subject: Re: Nullfs - Panic when umounting and lower fs has been removed Message-ID: <20130520073426.GY3047@kib.kiev.ua> In-Reply-To: <CAALwa8nrUbErf9hghdFBOD0Y6yGWD5wYPqQ1Ef4qx_pp7E3Z%2BA@mail.gmail.com> References: <CAALwa8nrUbErf9hghdFBOD0Y6yGWD5wYPqQ1Ef4qx_pp7E3Z%2BA@mail.gmail.com>
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On Sun, May 19, 2013 at 08:41:03PM +0000, Antoine Brodin wrote:
> Hi there,
>=20
> I encountered a panic on head today with nullfs using poudriere.
>=20
> It is quite easy to reproduce, the script is probably doing something
> wrong but panicking is not nice
>=20
> %%%
> mkdir /tmp/.new_packages /mnt/new_packages
> mount -t nullfs /tmp/.new_packages /mnt/new_packages
> dd if=3D/dev/zero of=3D/mnt/new_packages/bar count=3D20000
> mv /tmp/.new_packages/bar /tmp/
> rm -rf /tmp/.new_packages
> umount -f /mnt/new_packages
> %%%
>=20
> The panic:
>=20
> userret: returning with the following locks held:
> exclusive lockmgr ufs (ufs) r =3D 0 (0xfffffe0010a77548) locked @
> /usr/src/sys/modules/nullfs/../../fs/nullfs/null_vnops.c:615
> panic: witness_warn
> cpuid =3D 0
> KDB: enter: panic
This is strange, do you have witness enabled, but invariants not ?
Please try the following change.
diff --git a/sys/fs/nullfs/null_vfsops.c b/sys/fs/nullfs/null_vfsops.c
index ad02236..bece8c8 100644
--- a/sys/fs/nullfs/null_vfsops.c
+++ b/sys/fs/nullfs/null_vfsops.c
@@ -417,8 +417,13 @@ nullfs_unlink_lowervp(struct mount *mp, struct vnode *=
lowervp)
*/
if (vp->v_usecount =3D=3D 0) {
KASSERT((vp->v_iflag & VI_DOOMED) !=3D 0,
- ("not reclaimed %p", vp));
+ ("not reclaimed nullfs vnode %p", vp));
VOP_UNLOCK(vp, 0);
+ } else {
+ ASSERT_VOP_ELOCKED(vp, "unlink_lowervp");
+ KASSERT((vp->v_iflag & VI_DOOMED) =3D=3D 0,
+ ("reclaimed nullfs vnode %p", vp));
+ xp->null_flags &=3D ~NULLV_NOUNLOCK;
}
vdrop(vp);
}
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