Re: CVS commit: src/sys/kern

[Reinoud Zandijk <reinoud%13thmonkey.org@localhost>]

Hiya Antti,

On Wed, Nov 12, 2008 at 03:59:32PM +0200, Antti Kantee wrote:
> On Tue Nov 04 2008 at 16:08:41 +0000, Reinoud Zandijk wrote:
> > 
> > Module Name:        src
> > Committed By:       reinoud
> > Date:               Tue Nov  4 16:08:41 UTC 2008
> > 
> > Modified Files:
> >     src/sys/kern: vfs_bio.c
> > 
> > Log Message:
> > Don't dereference bp->b_vp->v_mount if its vnode type is VT_VNON. I dont
> > know if this masks a bug but with a machine having a ffs+wapbl mount, NFS
> > mounts and a ntfs mount this paniced the machine on suspend.
> 
> Where's the PR describing the actual problem?

There is no PR (yet); On suspend, all buffers on the bufhashtbl are 
visited and if they are mounted with softdep an action is taken.

During this visit, a buffer came by that was NOT assigned to a particular 
FS i.e. bp->b_vp->v_tag == VT_VNON. This buffer's bp->b_vp->v_mount was NOT 
NULL though but rather typically 0x40 and so the bp->b_vp->v_mount check 
failed. The kernel then dereferenced bp->b_vp->b_mount->mnt_flag to check 
for the softdeps flag and it paniced.

The bug masking i am refering to that aparently in some cases 
bp->b_vp->v_mount is not allways NULL or valid even though its v_tag is 
VT_NON.

With regards,
Reinoud