Merge v7.1.4linux-rolling-stable

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 25 insertions, 14 deletions

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index b8452dbdb043..d6e04041f5dc 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -2094,32 +2094,43 @@ out_unlock:
 		goto xa_unlocked;
 	}
 
-	if (!is_shmem) {
+xa_locked:
+	xas_unlock_irq(&xas);
+xa_unlocked:
+
+	/*
+	 * If collapse is successful, flush must be done now before copying.
+	 * If collapse is unsuccessful, does flush actually need to be done?
+	 * Do it anyway, to clear the state.
+	 */
+	try_to_unmap_flush();
+
+	if (result == SCAN_SUCCEED && !is_shmem && !mapping_large_folio_support(mapping)) {
+		/*
+		 * invalidate_lock as shared excludes against concurrent opens
+		 * in do_dentry_open() truncating the page cache. This is
+		 * particularly important if there are dirty folios in transit.
+		 */
+		filemap_invalidate_lock_shared(mapping);
 		filemap_nr_thps_inc(mapping);
 		/*
 		 * Paired with the fence in do_dentry_open() -> get_write_access()
 		 * to ensure i_writecount is up to date and the update to nr_thps
 		 * is visible. Ensures the page cache will be truncated if the
-		 * file is opened writable.
+		 * file is opened writable. If collapse looks to be successful,
+		 * flush any dirty pages out the page cache. With the nr_thps
+		 * incremented, there won't be any new writers (nor new dirties).
 		 */
 		smp_mb();
-		if (inode_is_open_for_write(mapping->host)) {
+		if (inode_is_open_for_write(mapping->host) || filemap_write_and_wait(mapping)) {
 			result = SCAN_FAIL;
 			filemap_nr_thps_dec(mapping);
+			filemap_invalidate_unlock_shared(mapping);
+			goto rollback;
 		}
+		filemap_invalidate_unlock_shared(mapping);
 	}
 
-xa_locked:
-	xas_unlock_irq(&xas);
-xa_unlocked:
-
-	/*
-	 * If collapse is successful, flush must be done now before copying.
-	 * If collapse is unsuccessful, does flush actually need to be done?
-	 * Do it anyway, to clear the state.
-	 */
-	try_to_unmap_flush();
-
 	if (result == SCAN_SUCCEED && nr_none &&
 	    !shmem_charge(mapping->host, nr_none))
 		result = SCAN_FAIL;