tcp: replace hard coded GFP_KERNEL with sk_allocation

This fixed a lockdep warning which appeared when doing stress
memory tests over NFS:

	inconsistent {RECLAIM_FS-ON-W} -> {IN-RECLAIM_FS-W} usage.

	page reclaim => nfs_writepage => tcp_sendmsg => lock sk_lock

	mount_root => nfs_root_data => tcp_close => lock sk_lock =>
			tcp_send_fin => alloc_skb_fclone => page reclaim

David raised a concern that if the allocation fails in tcp_send_fin(), and it's
GFP_ATOMIC, we are going to yield() (which sleeps) and loop endlessly waiting
for the allocation to succeed.

But fact is, the original GFP_KERNEL also sleeps. GFP_ATOMIC+yield() looks
weird, but it is no worse the implicit sleep inside GFP_KERNEL. Both could
loop endlessly under memory pressure.

CC: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
CC: David S. Miller <davem@davemloft.net>
CC: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 3 deletions

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index ce7d3b021ffc..0543561da999 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -886,7 +886,7 @@ int tcp_v4_md5_do_add(struct sock *sk, __be32 addr,
                         }
                         sk->sk_route_caps &= ~NETIF_F_GSO_MASK;
                 }
-                if (tcp_alloc_md5sig_pool() == NULL) {
+                if (tcp_alloc_md5sig_pool(sk) == NULL) {
                         kfree(newkey);
                         return -ENOMEM;
                 }
@@ -1007,8 +1007,9 @@ static int tcp_v4_parse_md5_keys(struct sock *sk, char __user *optval,
 
         if (!tcp_sk(sk)->md5sig_info) {
                 struct tcp_sock *tp = tcp_sk(sk);
-                struct tcp_md5sig_info *p = kzalloc(sizeof(*p), GFP_KERNEL);
+                struct tcp_md5sig_info *p;
 
+                p = kzalloc(sizeof(*p), sk->sk_allocation);
                 if (!p)
                         return -EINVAL;
 
@@ -1016,7 +1017,7 @@ static int tcp_v4_parse_md5_keys(struct sock *sk, char __user *optval,
                 sk->sk_route_caps &= ~NETIF_F_GSO_MASK;
         }
 
-        newkey = kmemdup(cmd.tcpm_key, cmd.tcpm_keylen, GFP_KERNEL);
+        newkey = kmemdup(cmd.tcpm_key, cmd.tcpm_keylen, sk->sk_allocation);
         if (!newkey)
                 return -ENOMEM;
         return tcp_v4_md5_do_add(sk, sin->sin_addr.s_addr,