Commit e8c7d14ac6c3 ("block: revert back to synchronous request_queue removal")
stops to release request queue from wq context because that commit
supposed all blk_put_queue() is called in context which is allowed
to sleep. However, this assumption isn't true because we release disk's
reference in partition's percpu_ref's ->release() which doesn't allow
to sleep, because the ->release() is run via call_rcu().
Fixes this issue by moving put disk reference into hd_struct_free_work()
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
Fixes: e8c7d14ac6c3 ("block: revert back to synchronous request_queue removal")
Reported-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Tested-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Cc: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Bart Van Assche <bvanassche@xxxxxxx>
---
block/partitions/core.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/block/partitions/core.c b/block/partitions/core.c
index e62a98a8eeb7..51376f1de8f8 100644
--- a/block/partitions/core.c
+++ b/block/partitions/core.c
@@ -278,6 +278,15 @@ static void hd_struct_free_work(struct work_struct *work)
{
struct hd_struct *part =
container_of(to_rcu_work(work), struct hd_struct, rcu_work);
+ struct gendisk *disk = part_to_disk(part);
+
+ /*
+ * Release disk reference grabbed in delete_partition, and it should
+ * have been done in hd_struct_free(), however device's release
+ * handler can't be run in percpu_ref's ->release() callback because
+ * it is run via call_rcu().
+ */
+ put_device(disk_to_dev(disk));
part->start_sect = 0;
part->nr_sects = 0;
@@ -293,7 +302,6 @@ static void hd_struct_free(struct percpu_ref *ref)
rcu_dereference_protected(disk->part_tbl, 1);
rcu_assign_pointer(ptbl->last_lookup, NULL);
- put_device(disk_to_dev(disk));
INIT_RCU_WORK(&part->rcu_work, hd_struct_free_work);
queue_rcu_work(system_wq, &part->rcu_work);
--
2.25.2
