veth: try harder when allocating queue memory

struct veth_rq is pretty large, 832B total without debug
options enabled. Since commit under Fixes we try to pre-allocate
enough queues for every possible CPU. Miao Wang reports that
this may lead to order-5 allocations which will fail in production.

Let the allocation fallback to vmalloc() and try harder.
These are the same flags we pass to netdev queue allocation.

Reported-and-tested-by: Miao Wang <[e-mail]>
Fixes: 9d3684c24a52 ("veth: create by default nr_possible_cpus queues")
Link: https://lore.kernel.org/all/[e-mail]/
Signed-off-by: Jakub Kicinski <[e-mail]>
Reviewed-by: Eric Dumazet <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Paolo Abeni <[e-mail]>

drivers/net/veth.c

···
 	struct veth_priv *priv = netdev_priv(dev);
 	int i;
 
-	priv->rq = kcalloc(dev->num_rx_queues, sizeof(*priv->rq), GFP_KERNEL_ACCOUNT);
+	priv->rq = kvcalloc(dev->num_rx_queues, sizeof(*priv->rq),
+			    GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);
 	if (!priv->rq)
 		return -ENOMEM;
 
···
 {
 	struct veth_priv *priv = netdev_priv(dev);
 
-	kfree(priv->rq);
+	kvfree(priv->rq);
 }
 
 static int veth_dev_init(struct net_device *dev)