XFS memory allocation deadlock in 2.6.38

[Sean Noonan]

>> Could you test if you see the deadlock before
>> 5ecfda041e4b4bd858d25bbf5a16c2a6c06d7272 without MAP_POPULATE ?

> Built and tested 72ddc8f72270758951ccefb7d190f364d20215ab.
> Confirmed that the original bug does not present in this version.
> Confirmed that removing MAP_POPULATE does cause the deadlock to occur.

git bisect leads to this:

bdfb04301fa5fdd95f219539a9a5b9663b1e5fc2 is the first bad commit
commit bdfb04301fa5fdd95f219539a9a5b9663b1e5fc2
Author: Christoph Hellwig <hch at infradead.org>
Date:   Wed Jan 20 21:55:30 2010 +0000

    xfs: replace KM_LARGE with explicit vmalloc use
    
    We use the KM_LARGE flag to make kmem_alloc and friends use vmalloc
    if necessary.  As we only need this for a few boot/mount time
    allocations just switch to explicit vmalloc calls there.
    
    Signed-off-by: Christoph Hellwig <hch at lst.de>
    Signed-off-by: Alex Elder <aelder at sgi.com>

:040000 040000 1eed68ced17d8794fa842396c01c3b9677c6e709 d462932a318f8c823fa2a73156e980a688968cb2 M	fs