[PATCH v4 0/3] mm/khugepaged: fix khugepaged+shmem races

[David Stevens <stevensd@chromium.org>]

From: David Stevens <stevensd@chromium.org>

Fix two races in khugepaged+shmem that cause issues with userfaultfd and
lseek, respectively.

v3 -> v4:
 - Base changes on mm-everything (fba720cb4dc0)
 - Add patch to refactor error handling control flow in collapse_file
 - Rebase userfaultfd patch with no significant logic changes
 - Different approach for fixing lseek race
v2 -> v3:
 - Use XA_RETRY_ENTRY to synchronize with reads from the page cache
   under the RCU read lock in userfaultfd fix
 - Add patch to fix lseek race
v1 -> v2:
 - Different approach for userfaultfd fix

David Stevens (3):
  mm/khugepaged: refactor collapse_file control flow
  mm/khugepaged: skip shmem with userfaultfd
  mm/khugepaged: maintain page cache uptodate flag

 include/trace/events/huge_memory.h |   3 +-
 mm/khugepaged.c                    | 263 ++++++++++++++++-------------
 2 files changed, 144 insertions(+), 122 deletions(-)

-- 
2.39.2.637.g21b0678d19-goog