For folios with mappings that have the AS_WRITEBACK_MAY_BLOCK flag set
on it, fail MIGRATE_SYNC mode migration with -EBUSY if the folio is
currently under writeback. If the AS_WRITEBACK_MAY_BLOCK flag is set on
the mapping, the writeback may take an indeterminate amount of time to
complete, so we cannot wait on writeback.
Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
---
mm/migrate.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index df91248755e4..1d038a4202ae 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1260,7 +1260,10 @@ static int migrate_folio_unmap(new_folio_t get_new_folio,
*/
switch (mode) {
case MIGRATE_SYNC:
- break;
+ if (!src->mapping ||
+ !mapping_writeback_may_block(src->mapping))
+ break;
+ fallthrough;
default:
rc = -EBUSY;
goto out;
--
2.43.5
