mm/mmu_notifier: kill invalidate_page

The invalidate_page callback suffered from two pitfalls.  First it used
to happen after the page table lock was release and thus a new page
might have setup before the call to invalidate_page() happened.

This is in a weird way fixed by commit c7ab0d2fdc84 ("mm: convert
try_to_unmap_one() to use page_vma_mapped_walk()") that moved the
callback under the page table lock but this also broke several existing
users of the mmu_notifier API that assumed they could sleep inside this
callback.

The second pitfall was invalidate_page() being the only callback not
taking a range of address in respect to invalidation but was giving an
address and a page.  Lots of the callback implementers assumed this
could never be THP and thus failed to invalidate the appropriate range
for THP.

By killing this callback we unify the mmu_notifier callback API to
always take a virtual address range as input.

Finally this also simplifies the end user life as there is now two clear
choices:
  - invalidate_range_start()/end() callback (which allow you to sleep)
  - invalidate_range() where you can not sleep but happen right after
    page table update under page table lock

Signed-off-by: Jérôme Glisse <[email protected]>
Cc: Bernhard Held <[email protected]>
Cc: Adam Borowski <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Radim Krčmář <[email protected]>
Cc: Wanpeng Li <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: Takashi Iwai <[email protected]>
Cc: Nadav Amit <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: axie <[email protected]>
Cc: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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