net: tun: change tun_alloc_skb() to allow bigger paged allocations

tun_alloc_skb() is currently calling sock_alloc_send_pskb()
forcing order-0 page allocations.

Switch to PAGE_ALLOC_COSTLY_ORDER, to increase max allocation size by 8x.

Also add logic to increase the linear part if needed.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Tahsin Erdogan <trdgn@amazon.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20230801205254.400094-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index d75456a..8a48431 100644 (file)
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1526,8 +1526,10 @@ static struct sk_buff *tun_alloc_skb(struct tun_file *tfile,
        if (prepad + len < PAGE_SIZE || !linear)
                linear = len;
 
+       if (len - linear > MAX_SKB_FRAGS * (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER))
+               linear = len - MAX_SKB_FRAGS * (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER);
        skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,
-                                  &err, 0);
+                                  &err, PAGE_ALLOC_COSTLY_ORDER);
        if (!skb)
                return ERR_PTR(err);