v3.13-rc6+ regression (ARM board)

On Tue, Dec 31, 2013 at 11:37:21AM +0100, Krzysztof Ha??asa wrote:

Hi,

There seems to be a regression in v3.13-rc6+ (up to current tip =
71ce176ee6ed1735b9a1160a5704a915d13849b1).

Board is Gateworks Cambria, CPU Intel IXP435 ARM big endian, gcc 4.7.3.
The board boots correctly and works (shell mostly, and SSHD) for about
50 seconds. After 52-54 seconds, it frozes dead without any console
(UART) output.

Bisecting shows 5e30025a319910695f5010dc0fb53a23299da14d as the first
bad commit. Interestingly it's a merge:

   Merge branch 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

    Pull core locking changes from Ingo Molnar:
     "The biggest changes:

       - add lockdep support for seqcount/seqlocks structures, this
         unearthed both bugs and required extra annotation.

       - move the various kernel locking primitives to the new
         kernel/locking/ directory"

Both parents of this merge consistently show no such problem. The merge
is basically automatic, I don't see any suspect there.

Any ideas?

No, but FWIW it works fine here on an armada370 (armv7). That doesn't
mean there's no bug, just that I'm not hitting it :-)

Willy