nvme: fix nvme_ns_remove() deadlock
On receipt of a namespace attribute changed AER, we acquire the
namespace mutex lock before proceeding to scan and validate the
namespace list. In case of namespace detach/delete command,
nvme_ns_remove function deadlocks trying to acquire the already held
lock.
All callers, except nvme_remove_namespaces(), of nvme_ns_remove()
already held namespaces_mutex. So we can simply fix the deadlock by
not acquiring the mutex in nvme_ns_remove() and acquiring it in
nvme_remove_namespaces().
Reported-by: Sunad Bhandary S <sunad.s@samsung.com>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Sagi Grimerg <sagi@grimberg.me>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 3428c02..2de248b 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1452,6 +1452,8 @@
static void nvme_ns_remove(struct nvme_ns *ns)
{
+ lockdep_assert_held(&ns->ctrl->namespaces_mutex);
+
if (test_and_set_bit(NVME_NS_REMOVING, &ns->flags))
return;
@@ -1464,9 +1466,7 @@
blk_mq_abort_requeue_list(ns->queue);
blk_cleanup_queue(ns->queue);
}
- mutex_lock(&ns->ctrl->namespaces_mutex);
list_del_init(&ns->list);
- mutex_unlock(&ns->ctrl->namespaces_mutex);
synchronize_rcu();
nvme_put_ns(ns);
}
@@ -1580,8 +1580,10 @@
{
struct nvme_ns *ns, *next;
+ mutex_lock(&ctrl->namespaces_mutex);
list_for_each_entry_safe(ns, next, &ctrl->namespaces, list)
nvme_ns_remove(ns);
+ mutex_unlock(&ctrl->namespaces_mutex);
}
EXPORT_SYMBOL_GPL(nvme_remove_namespaces);