From: Tao Su <tao1.su@xxxxxxxxxxxxxxx>
[ Upstream commit 8176080d59e6d4ff9fc97ae534063073b4f7a715 ]
Kernel hang in blkg_destroy_all() when total blkg greater than
BLKG_DESTROY_BATCH_SIZE, because of not removing destroyed blkg in
blkg_list. So the size of blkg_list is same after destroying a
batch of blkg, and the infinite 'restart' occurs.
Since blkg should stay on the queue list until blkg_free_workfn(),
skip destroyed blkg when restart a new round, which will solve this
kernel hang issue and satisfy the previous will to restart.
Reported-by: Xiangfei Ma <xiangfeix.ma@xxxxxxxxx>
Tested-by: Xiangfei Ma <xiangfeix.ma@xxxxxxxxx>
Tested-by: Farrah Chen <farrah.chen@xxxxxxxxx>
Signed-off-by: Tao Su <tao1.su@xxxxxxxxxxxxxxx>
Fixes: f1c006f1c685 ("blk-cgroup: synchronize pd_free_fn() from blkg_free_workfn() and blkcg_deactivate_policy()")
Suggested-and-reviewed-by: Yu Kuai <yukuai3@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230428045149.1310073-1-tao1.su@xxxxxxxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
block/blk-cgroup.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 7c91d9195da8d..60f366f98fa2b 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -468,6 +468,9 @@ static void blkg_destroy_all(struct gendisk *disk)
list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) {
struct blkcg *blkcg = blkg->blkcg;
+ if (hlist_unhashed(&blkg->blkcg_node))
+ continue;
+
spin_lock(&blkcg->lock);
blkg_destroy(blkg);
spin_unlock(&blkcg->lock);
--
2.39.2
