Re: btrfs GPF in read_extent_buffer() while scrubbing with kernel 3.4.2

[Chris Mason <chris.mason@fusionio.com>]

On Fri, Jul 06, 2012 at 08:33:51AM -0600, Sami Liedes wrote:
> On Fri, Jul 06, 2012 at 12:42:50PM +0200, Jan Schmidt wrote:
> > I've no good idea at the moment how to go on. It might help to get a feeling if
> > it's shifting around at least a little bit or really constant in the timing of
> > occurrence. So can you please apply the next patch on top of the other two and
> > give it some more failure tries? The "checksum mismatch [1234]" line will be of
> > most interest. I'm also curious what the additional debug variables will say in
> > the extended version of the very first printk. You can leave out the stack
> > traces if you like, they won't matter much anyway.
> 
> Ok. Also turned on CONFIG_DEBUG_PAGEALLOC and CONFIG_SLUB_DEBUG_ON as
> suggested by Chris Mason.
> 
> With those and the latest patch, there's an oops already at boot. I
> don't have netconsole yet at that point, but here's the important
> parts (sure I can capture it fully if you need).
> 
> By the way, something seems to be untabifying your patches. I don't
> know if it's on my side or yours, but at least some other patches I
> receive via linux-btrfs contain tabs. Doing a M-x tabify in emacs
> mostly makes them apply cleanly for me.
> 
> 	Sami
> 
> 
> ------------------------------------------------------------
> btrfs: disk space caching is enabled
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000150
> IP: [<ffffffffa0223568>] check_node+0x138/0x250 [btrfs]

This isn't from any of the new debugging.  Can you please try it on an
unpatched kernel?

-chris