[Trusty] Hang and corruption in dcache_shrink_list

[Dave Chiluk]

BugLink: http://bugs.launchpad.net/bugs/1354157

The patchset described here and committed to upstream
https://lkml.org/lkml/2014/5/4/7
can be cleanly cherry-picked, and has been applied to
git://kernel.ubuntu.com/chiluk/ubuntu-trusty.git branch 70318
The end user reports that the above patch set fixes the issue.

I'd like to get some additional review on this patchset before
submitting it for actual inclusion.

That all being said, I think we should strongly consider pulling in
046b961b4
b2b80195d
9f12600fe
and b2b80195d88
as well, as these look to be more related to a possible lock starvation
case.

Open for discussion.
Dave.