mm/hmm: Hold on to the mmget for the lifetime of the range

Range functions like hmm_range_snapshot() and hmm_range_fault() call
find_vma, which requires hodling the mmget() and the mmap_sem for the mm.

Make this simpler for the callers by holding the mmget() inside the range
for the lifetime of the range. Other functions that accept a range should
only be called if the range is registered.

This has the side effect of directly preventing hmm_release() from
happening while a range is registered. That means range->dead cannot be
false during the lifetime of the range, so remove dead and
hmm_mirror_mm_is_alive() entirely.

Signed-off-by: Jason Gunthorpe <[email protected]>
Reviewed-by: John Hubbard <[email protected]>
Reviewed-by: Ralph Campbell <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Tested-by: Philip Yang <[email protected]>

0 files changed, 0 insertions, 0 deletions