Unverified Commit 095f627a authored by Jens Axboe's avatar Jens Axboe Committed by Christian Brauner
Browse files

mm/filemap: gate dropbehind invalidate on folio !dirty && !writeback 



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: default avatarAl Viro <viro@zeniv.linux.org.uk>
Fixes: fb7d3bc4 ("mm/filemap: drop streaming/uncached pages when writeback completes")
Link: https://lore.kernel.org/linux-fsdevel/20250525083209.GS2023217@ZenIV/


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/20250527133255.452431-2-axboe@kernel.dk


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 015a99fa

mm/filemap.c

+11 −2
Original line number Diff line number Diff line
@@ -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);

	}

}