Re: kdevtmpfs oops since yesterdays vfs merge

Dave Jones
2011-07-25T01:56:15Z

On Sun, Jul 24, 2011 at 09:53:24PM -0400, Dave Jones wrote:
> On Mon, Jul 25, 2011 at 12:51:54AM +0100, Al Viro wrote:
> > On Sun, Jul 24, 2011 at 07:40:29PM -0400, Dave Jones wrote:
> > > On Mon, Jul 25, 2011 at 12:28:12AM +0100, Al Viro wrote:
> > > > On Sun, Jul 24, 2011 at 07:17:01PM -0400, Dave Jones wrote:
> > > > > I see an oops in handle_create when I try to boot current tree..
> > > > >
> > > > > full trace:
> > > > > https://s3.amazonaws.com/twitpic/photos/large/355006460.jpg?AWSAccessKeyId=AKIAJF3XCCKACR3QDMOA&Expires=1311550232&Signature=IIO%2Bya1uEDJzSXTD0DXh2%2BdZpoU%3D
> > > >
> > > > Where in handle_create() is that? At least dump objdump -d of your
> > > > devtmpfs.o someplace readable...
> > >
> > > http://codemonkey.org.uk/devtmpfs.s
> >
> > Smells like req->dev somehow managing to be NULL at that point, but that
> > doesn't make any sense - we get to devtmpfs_create_node() only from one
> > place, it sets req.dev to the argument it got from callers and that caller
> > would have oopsed itself before getting to that call with dev == NULL...
> >
> > Could you stick a BUG_ON(!dev) in the beginning of handle_create() to see
> > if that's what somehow manages to happen?
>
> So I built a kernel with this, and then couldn't reproduce it.
> Made a clean kernel again, and still nothing.. After a number of reboots,
> it finally triggered again, with that BUG_ON(). fwiw 'nodename' is pointing
> at garbage when that happens too.
>
> Either it only triggers occasionally, or it's dependent on how quickly
> I type my luks password in.

one more datapoint. On a succesful boot, I see ..

[ 7.760774] dracut: luksOpen /dev/sda2 luks-b5a1fb36-5672-4191-a260-e3f389eb0bb6
[ 14.787158] nodename: dm-0
[ 15.082391] nodename: dm-0

when it triggers the bug_on(), it's that second nodename that is garbage.

Dave