Re: [Bug #16306] 2.6.35-rc3 BUG: unable to handle kernel NULL pointer dereference at 0000000000000048 cifs_show_options

Jeff Layton
2010-07-09T00:49:45Z

On Fri, 9 Jul 2010 01:41:39 +0200 (CEST)
"Rafael J. Wysocki" <rjw-KKrjLPT3xs0@public.gmane.org> wrote:

> This message has been generated automatically as a part of a summary report
> of recent regressions.
>
> The following bug entry is on the current list of known regressions
> from 2.6.34. Please verify if it still should be listed and let the tracking team
> know (either way).
>
>
> Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=16306
> Subject : 2.6.35-rc3 BUG: unable to handle kernel NULL pointer dereference at 0000000000000048 cifs_show_options
> Submitter : Andrew Hendry <andrew.hendry-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> Date : 2010-06-26 10:46 (13 days old)
> Message-ID : <AANLkTilhTrEBYZd4HxeXQk8B6-yV8rCJ2C0jXsEREgIR-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
> References : http://marc.info/?l=linux-kernel&m=127754922110501&w=2
> Handled-By : Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>
>

Not sure if this is a new bug or not...

I don't think this is really a CIFS bug, per-se. It seems like the
problem may be that the iterator for /proc/pid/mountinfo is not
sufficiently protected against removal from the vfsmount list.

Filesystems don't seem to be expected to do any locking in their
show_options routines though so I'm guessing that something is borked
in the generic vfs layer.

Either that or this is some sort of generic mem corruption? I'm open to
input from others that have a better grasp of this stuff at the VFS
layer...

--
Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>