4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dongli Zhang <dongli.zhang@xxxxxxxxxx> commit 87557efc27f6a50140fb20df06a917f368ce3c66 upstream. While grant reference is of type uint32_t, xen-netfront erroneously casts it to signed short in BUG_ON(). This would lead to the xen domU panic during boot-up or migration when it is attached with lots of paravirtual devices. Signed-off-by: Dongli Zhang <dongli.zhang@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Cc: Blake Cooper <blake.cooper@xxxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/xen-netfront.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -304,7 +304,7 @@ static void xennet_alloc_rx_buffers(stru queue->rx_skbs[id] = skb; ref = gnttab_claim_grant_reference(&queue->gref_rx_head); - BUG_ON((signed short)ref < 0); + WARN_ON_ONCE(IS_ERR_VALUE((unsigned long)ref)); queue->grant_rx_ref[id] = ref; page = skb_frag_page(&skb_shinfo(skb)->frags[0]); @@ -437,7 +437,7 @@ static void xennet_tx_setup_grant(unsign id = get_id_from_freelist(&queue->tx_skb_freelist, queue->tx_skbs); tx = RING_GET_REQUEST(&queue->tx, queue->tx.req_prod_pvt++); ref = gnttab_claim_grant_reference(&queue->gref_tx_head); - BUG_ON((signed short)ref < 0); + WARN_ON_ONCE(IS_ERR_VALUE((unsigned long)ref)); gnttab_grant_foreign_access_ref(ref, queue->info->xbdev->otherend_id, gfn, GNTMAP_readonly);