Pass mp to kmem_alloc and friends?

[Eric Sandeen]

I had a request for the kmem_alloc deadlock warning to print the
filesystem involved.

Any objections to passing mp into kmem_alloc() and friends whenever
it's reasonably available from the caller?

It'd be a big mechanical change, don't want to embark on that unless
it seems acceptable & useful.

I think we generally know the root causes of the most common deadlock
warnings, but it's a warm fuzzy to give as much info as possible.

Heck, I almost wonder if passing a descriptive string in, for at
least the problematic cases we know about, i.e. "extent map realloc"
so we'd get something like:

XFS (sdb1): myprocess(123) possible memory allocation deadlock size 12345 during extent map realloc in kmem_alloc (mode:0x250)

I dunno ... too much? :)

-Eric