mm/shmem: fix race in shmem_undo_range w/THP

Split folios during the second loop of shmem_undo_range.  It's not
sufficient to only split folios when dealing with partial pages, since
it's possible for a THP to be faulted in after that point.  Calling
truncate_inode_folio in that situation can result in throwing away data
outside of the range being targeted.

[[email protected]: tidy up comment layout]
Link: https://lkml.kernel.org/r/[email protected]
Fixes: b9a8a4195c7d ("truncate,shmem: Handle truncates that split large folios")
Signed-off-by: David Stevens <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Suleiman Souhlal <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions