[PATCH v5 0/3] mm/khugepaged: fix khugepaged+shmem races

[David Stevens]

From: David Stevens <stevensd@xxxxxxxxxxxx>

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

v4 -> v5:
 - Rebase on mm-unstable (9caa15b8a499)
 - Gather acks
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                    | 259 ++++++++++++++++-------------
 2 files changed, 142 insertions(+), 120 deletions(-)

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2.40.0.rc0.216.gc4246ad0f0-goog