Re: vfs related crash in 2.6.33-rc2

Andrew Morton
2010-01-06T23:41:44Z

On Thu, 31 Dec 2009 05:59:32 +0900
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> wrote:

> Marvin <marvin24@gmx.de> writes:
>
> >> Marvin <marvin24@gmx.de> writes:
> >> > Hi,
> >> >
> >> > I'm getting a lot of these:
> >> >
> >> > kernel: general protection fault: 0000 [#1] SMP
> >> > kernel: last sysfs file: /sys/devices/pci0000:00/0000:00:18.3/modalias
> >> > kernel: CPU 0
> >> > kernel: Pid: 12177, comm: packagekitd Not tainted 2.6.33-rc2 #1
> >> > ...
> >> >
> >> > filesystem is ext4 (in case it matters).
> >>
> >> BTW, are you using nfs client on this machine?
> >>
> >
> > um - yes, now that I think about it... I killed a nfs umount process (because of an
> > offline server) shortly before the oopses started to fire.
>
> OK. Probably, this oops would be same with one which happened on my
> machine recently. That path in patch corrupts dcache hash, so it can be
> the cause of strange behavior or oops on dcache hash.
>
> If so, the attached patch would fix it.
>
> Thanks.
> --
> OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
>
>
> Recent change is missing to update "rehash". With that change, it will
> become the cause of adding dentry to hash twice.
>
> This explains the reason of Oops (dereference the freed dentry in
> __d_lookup()) on my machine.
>
> Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
> ---
>
> fs/nfs/dir.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff -puN fs/nfs/dir.c~nfs-d_rehash-fix fs/nfs/dir.c
> --- linux-2.6/fs/nfs/dir.c~nfs-d_rehash-fix 2009-12-28 06:18:09.000000000 +0900
> +++ linux-2.6-hirofumi/fs/nfs/dir.c 2009-12-28 06:18:16.000000000 +0900
> @@ -1615,6 +1615,7 @@ static int nfs_rename(struct inode *old_
> goto out;
>
> new_dentry = dentry;
> + rehash = NULL;
> new_inode = NULL;
> }
> }

Guys, what's the status of this fix? Did Marvin have a chance to test
it? Are the NFS developers aware of it?

Thanks.