kobject_uevent may allocate memory and it may be called while there are dm
devices suspended. The allocation may recurse into a suspended device,
causing a deadlock. We must set the noio flag when sending a uevent.

The observed deadlock was reported here:
https://www.redhat.com/archives/dm-devel/2020-March/msg00025.htmlReported-by: NKhazhismel Kumykov <khazhy@google.com>
Reported-by: NTahsin Erdogan <tahsin@google.com>
Reported-by: NGabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: NMike Snitzer <snitzer@redhat.com>