mld: avoid unnecessary high order page allocation in mld_newpack()

If link mtu is too big, mld_newpack() allocates high-order page.
But most mld packets don't need high-order page.
So, it might waste unnecessary pages.
To avoid this, it makes mld_newpack() try to allocate order-0 page.

Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index d36ef9d..54ec163 100644 (file)
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1729,22 +1729,25 @@ static void ip6_mc_hdr(struct sock *sk, struct sk_buff *skb,
 
 static struct sk_buff *mld_newpack(struct inet6_dev *idev, unsigned int mtu)
 {
+       u8 ra[8] = { IPPROTO_ICMPV6, 0, IPV6_TLV_ROUTERALERT,
+                    2, 0, 0, IPV6_TLV_PADN, 0 };
        struct net_device *dev = idev->dev;
-       struct net *net = dev_net(dev);
-       struct sock *sk = net->ipv6.igmp_sk;
-       struct sk_buff *skb;
-       struct mld2_report *pmr;
-       struct in6_addr addr_buf;
-       const struct in6_addr *saddr;
        int hlen = LL_RESERVED_SPACE(dev);
        int tlen = dev->needed_tailroom;
-       unsigned int size = mtu + hlen + tlen;
+       struct net *net = dev_net(dev);
+       const struct in6_addr *saddr;
+       struct in6_addr addr_buf;
+       struct mld2_report *pmr;
+       struct sk_buff *skb;
+       unsigned int size;
+       struct sock *sk;
        int err;
-       u8 ra[8] = { IPPROTO_ICMPV6, 0,
-                    IPV6_TLV_ROUTERALERT, 2, 0, 0,
-                    IPV6_TLV_PADN, 0 };
 
-       /* we assume size > sizeof(ra) here */
+       sk = net->ipv6.igmp_sk;
+       /* we assume size > sizeof(ra) here
+        * Also try to not allocate high-order pages for big MTU
+        */
+       size = min_t(int, mtu, PAGE_SIZE / 2) + hlen + tlen;
        skb = sock_alloc_send_skb(sk, size, 1, &err);
        if (!skb)
                return NULL;