From: Ming Lei ming.lei@redhat.com
[ 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@kernel.org Reported-by: Bruno Goncalves bgoncalv@redhat.com Link: https://lore.kernel.org/linux-block/CA+QYu4rzz6079ighEanS3Qq_Dmnczcf45ZoJoHK... Signed-off-by: Ming Lei ming.lei@redhat.com Acked-by: Tejun Heo tj@kernel.org Link: https://lore.kernel.org/r/20210803070608.1766400-1-ming.lei@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- 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 5fac3757e6e0..0e56557cacf2 100644 --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -3061,19 +3061,19 @@ 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; }