From: Ming Lei <ming.lei@xxxxxxxxxx> [ Upstream commit 11431e26c9c43fa26f6b33ee1a90989f57b86024 ] blkcg->lock depends on q->queue_lock which may depend on another driver lock required in irq context, one example is dm-thin: Chain exists of: &pool->lock#3 --> &q->queue_lock --> &blkcg->lock Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&blkcg->lock); local_irq_disable(); lock(&pool->lock#3); lock(&q->queue_lock); <Interrupt> lock(&pool->lock#3); Fix the issue by using spin_lock_irq(&blkcg->lock) in ioc_weight_write(). Cc: Tejun Heo <tj@xxxxxxxxxx> Reported-by: Bruno Goncalves <bgoncalv@xxxxxxxxxx> Link: https://lore.kernel.org/linux-block/CA+QYu4rzz6079ighEanS3Qq_Dmnczcf45ZoJoHKVLVATTo1e4Q@xxxxxxxxxxxxxx/T/#u Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> Acked-by: Tejun Heo <tj@xxxxxxxxxx> Link: https://lore.kernel.org/r/20210803070608.1766400-1-ming.lei@xxxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- block/blk-iocost.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/block/blk-iocost.c b/block/blk-iocost.c index b7d8a954d99c..e95b93f72bd5 100644 --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -3039,19 +3039,19 @@ static ssize_t ioc_weight_write(struct kernfs_open_file *of, char *buf, if (v < CGROUP_WEIGHT_MIN || v > CGROUP_WEIGHT_MAX) return -EINVAL; - spin_lock(&blkcg->lock); + spin_lock_irq(&blkcg->lock); iocc->dfl_weight = v * WEIGHT_ONE; hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { struct ioc_gq *iocg = blkg_to_iocg(blkg); if (iocg) { - spin_lock_irq(&iocg->ioc->lock); + spin_lock(&iocg->ioc->lock); ioc_now(iocg->ioc, &now); weight_updated(iocg, &now); - spin_unlock_irq(&iocg->ioc->lock); + spin_unlock(&iocg->ioc->lock); } } - spin_unlock(&blkcg->lock); + spin_unlock_irq(&blkcg->lock); return nbytes; } -- 2.30.2
