It's possible for the folio to either get marked for writeback or redirtied. Add a helper, filemap_end_dropbehind(), which guards the folio_unmap_invalidate() call behind check for the folio being both non-dirty and not under writeback AFTER the folio lock has been acquired. Use this helper folio_end_dropbehind_write().

Cc: stable@vger.kernel.org Reported-by: Al Viro viro@zeniv.linux.org.uk Fixes: fb7d3bc41493 ("mm/filemap: drop streaming/uncached pages when writeback completes") Link: https://lore.kernel.org/linux-fsdevel/20250525083209.GS2023217@ZenIV/ Signed-off-by: Jens Axboe axboe@kernel.dk --- mm/filemap.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c index 7b90cbeb4a1a..008a55290f34 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1589,6 +1589,16 @@ int folio_wait_private_2_killable(struct folio *folio) } EXPORT_SYMBOL(folio_wait_private_2_killable);

+static void filemap_end_dropbehind(struct folio *folio) +{ + struct address_space *mapping = folio->mapping; + + VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); + + if (mapping && !folio_test_writeback(folio) && !folio_test_dirty(folio)) + folio_unmap_invalidate(mapping, folio, 0); +} + /* * If folio was marked as dropbehind, then pages should be dropped when writeback * completes. Do that now. If we fail, it's likely because of a big folio - @@ -1604,8 +1614,7 @@ static void folio_end_dropbehind_write(struct folio *folio) * invalidation in that case. */ if (in_task() && folio_trylock(folio)) { - if (folio->mapping) - folio_unmap_invalidate(folio->mapping, folio, 0); + filemap_end_dropbehind(folio); folio_unlock(folio); } }