Re: kdevtmpfs oops since yesterdays vfs merge

[Dave Jones <davej@redhat.com>]

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.

	Dave