Subject: Re: linux-next: Tree for Dec 4

From: Jeremiah Mahler <[email-masked]>
Date: Thu, 4 Dec 2014 16:54:01 -0800

all,

On Thu, Dec 04, 2014 at 03:34:11PM -0800, Jeremiah Mahler wrote:
> all,
> 
> On Thu, Dec 04, 2014 at 07:59:28PM +1100, Stephen Rothwell wrote:
> > Hi all,
> > 
> > Changes since 20141203:
> > 
[...]
> > 
> > -- 
> > Cheers,
> > Stephen Rothwell                    [email-masked]
> > 
> [...]
> 
> linux-next 20141204 is broken on all my machines, 20141203 worked fine.
> 
> They fail very early in the boot process and are unable to mount root.
> There are lots of "ext4_check_descriptors: Checksum for group ...
> failed" messages.
> 
> Any suggestions for where to start looking?
> 
> -- 
> - Jeremiah Mahler

I ran a bisect and found this patch to be faulty.

  commit fdfe073987619ec375da8d8a2701ab271d1b1339
  Author: Dmitry Monakhov <[email-masked]>
  Date:   Tue Dec 2 16:09:16 2014 -0500
  
      ext4: fix potential use after free during resize
      
      We need some sort of synchronization while updating ->s_group_desc
      because there are a lot of users which can access old ->s_group_desc
      array after it was released.
      
      Signed-off-by: Dmitry Monakhov <[email-masked]>
      Signed-off-by: Theodore Ts'o <[email-masked]>

-- 
- Jeremiah Mahler