From: Tao Su tao1.su@linux.intel.com
[ 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@intel.com Tested-by: Xiangfei Ma xiangfeix.ma@intel.com Tested-by: Farrah Chen farrah.chen@intel.com Signed-off-by: Tao Su tao1.su@linux.intel.com Fixes: f1c006f1c685 ("blk-cgroup: synchronize pd_free_fn() from blkg_free_workfn() and blkcg_deactivate_policy()") Suggested-and-reviewed-by: Yu Kuai yukuai3@huawei.com Link: https://lore.kernel.org/r/20230428045149.1310073-1-tao1.su@linux.intel.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- 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);