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: Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> Signed-off-by: Tao Su <tao1.su@xxxxxxxxxxxxxxx> --- v2: - change 'directly remove destroyed blkg' to 'skip destroyed blkg' v1: - https://lore.kernel.org/all/20230425075911.839539-1-tao1.su@xxxxxxxxxxxxxxx/ block/blk-cgroup.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index bd50b55bdb61..75bad5d60c9f 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -528,6 +528,9 @@ 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); -- 2.34.1
