On 23.11.24 00:23, Joanne Koong wrote:
For migrations called in MIGRATE_SYNC mode, skip migrating the folio if
it is under writeback and has the AS_WRITEBACK_INDETERMINATE flag set on its
mapping. If the AS_WRITEBACK_INDETERMINATE flag is set on the mapping, the
writeback may take an indeterminate amount of time to complete, and
waits may get stuck.
Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
Reviewed-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
---
mm/migrate.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index df91248755e4..fe73284e5246 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_indeterminate(src->mapping))
+ break;
+ fallthrough;
default:
rc = -EBUSY;
goto out;
Ehm, doesn't this mean that any fuse user can essentially completely
block CMA allocations, memory compaction, memory hotunplug, memory
poisoning... ?!
That sounds very bad.
--
Cheers,
David / dhildenb
