wait_split_huge_page() dependence on rmap.h

[Dave Hansen <dave@linux.vnet.ibm.com>]

wait_split_huge_page() is really only used in a few spots at the moment.
I was trying to use it in fs/proc/task_mmu.c, but simply including
huge_mm.h gets this:

fs/proc/task_mmu.c: In function a??smaps_pte_rangea??:
fs/proc/task_mmu.c:392: error: dereferencing pointer to incomplete type

I think it's due to the __anon_vma dereference below.  #including rmap.h
makes it go away, but I don't think it's really the correct thing to do
here.  Directly including rmap.h in huge_mm.h ends up with some really
interesting header dependencies and does not work either.

Any ideas?  Should we move the existing huge_mm.h stuff to a private
header and have a more public one that also brings in rmap.h?

#define wait_split_huge_page(__anon_vma, __pmd)                         \
        do {                                                            \
                pmd_t *____pmd = (__pmd);                               \
                spin_unlock_wait(&(__anon_vma)->root->lock);            \
                /*                                                      \
                 * spin_unlock_wait() is just a loop in C and so the    \
                 * CPU can reorder anything around it.                  \
                 */                                                     \
                smp_mb();                                               \
                BUG_ON(pmd_trans_splitting(*____pmd) ||                 \
                       pmd_trans_huge(*____pmd));                       \
        } while (0)


-- Dave

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