Commit 425bec00 authored by David Hildenbrand's avatar David Hildenbrand Committed by Linus Torvalds
Browse files

virtio-mem: fix sleeping in RCU read side section in virtio_mem_online_page_cb() 



virtio_mem_set_fake_offline() might sleep now, and we call it under
rcu_read_lock(). To fix it, simply move the rcu_read_unlock() further
up, as we're done with the device.

Reported-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Fixes: 6cc26d77: "virtio-mem: use page_offline_(start|end) when setting PageOffline()
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5a61b7a2

drivers/virtio/virtio_mem.c

+8 −1
Original line number Diff line number Diff line
@@ -1242,12 +1242,19 @@ static void virtio_mem_online_page_cb(struct page *page, unsigned int order) 
			do_online = virtio_mem_bbm_get_bb_state(vm, id) !=

				    VIRTIO_MEM_BBM_BB_FAKE_OFFLINE;

		}



		/*

		 * virtio_mem_set_fake_offline() might sleep, we don't need

		 * the device anymore. See virtio_mem_remove() how races

		 * between memory onlining and device removal are handled.

		 */

		rcu_read_unlock();



		if (do_online)

			generic_online_page(page, order);

		else

			virtio_mem_set_fake_offline(PFN_DOWN(addr), 1 << order,

						    false);

		rcu_read_unlock();

		return;

	}

	rcu_read_unlock();