[0/2] mm, thp: fix file-backed THP race in collapse_file

Message

Rongwei Wang Sept. 6, 2021, 12:11 p.m. UTC

Hi,
We found two bugs related to file-backed THP in our cases, recently.
The two bugs rough description as following:

1) in truncate_inode_pages_range, subpage(s) of file-backed THP can be
revealed by find_get_entry.

2) 'collapse_file' miss the pages which in writeback but no private.
This situation will be triggered in XFS when block size is set to
PAGESIZE.

These two patchs mainly fix the above mentioned bugs, and have been
tested in latest branch.

Rongwei Wang (2):
  mm, thp: check page mapping when truncating page cache
  mm, thp: bail out early in collapse_file for writeback page

 mm/filemap.c    |  7 ++++++-
 mm/khugepaged.c |  3 ++-
 mm/truncate.c   | 17 ++++++++++++++++-
 3 files changed, 24 insertions(+), 3 deletions(-)