virtio-mem: convert most offline_and_remove_memory() errors to -EBUSY

Just like we do with alloc_contig_range(), let's convert all unknown
errors to -EBUSY, but WARN so we can look into the issue. For example,
offline_pages() could fail with -EINTR, which would be unexpected in our
case.

Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20230713145551.2824980-3-david@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index ed15d2a..1a76ba2 100644 (file)
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -741,11 +741,15 @@ static int virtio_mem_offline_and_remove_memory(struct virtio_mem *vm,
                 * immediately instead of waiting.
                 */
                virtio_mem_retry(vm);
-       } else {
-               dev_dbg(&vm->vdev->dev,
-                       "offlining and removing memory failed: %d\n", rc);
+               return 0;
        }
-       return rc;
+       dev_dbg(&vm->vdev->dev, "offlining and removing memory failed: %d\n", rc);
+       /*
+        * We don't really expect this to fail, because we fake-offlined all
+        * memory already. But it could fail in corner cases.
+        */
+       WARN_ON_ONCE(rc != -ENOMEM && rc != -EBUSY);
+       return rc == -ENOMEM ? -ENOMEM : -EBUSY;
 }
 
 /*