On Mon, Jul 06, 2009 at 06:52:16PM +0800, Herbert Xu wrote:
> Wu Fengguang <fengguang.wu@xxxxxxxxx> wrote:
> >
> > This lockdep warning appears when doing stress memory tests over NFS.
> >
> > page reclaim => nfs_writepage => tcp_sendmsg => lock sk_lock
> >
> > tcp_close => lock sk_lock => tcp_send_fin => alloc_skb_fclone => page reclaim
>
> Well perhaps not this particular path, but it is certainly possible
> if an existing NFS socket dies and NFS tries to reestablish it.
>
> I suggest that NFS should utilise the sk_allocation field and
> set an appropriate value. Note that you may have to patch TCP
> so that it uses sk_allocation everywhere necessary, e.g., in
> tcp_send_fin.
Good suggestion! NFS already sets sk_allocation to GFP_ATOMIC in
linux/net/sunrpc/xprtsock.c <<xs_tcp_finish_connecting>>.
To fix this warning and possible recursions, I converted some
GPF_KERNEL cases to sk_allocation in the tcp/ipv4 code:
---
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.
mount_root => nfs_root_data => tcp_close => lock sk_lock =>
tcp_send_fin => alloc_skb_fclone => page reclaim
page reclaim => nfs_writepage => tcp_sendmsg => lock sk_lock
CC: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxxxxxxx>
CC: David S. Miller <davem@xxxxxxxxxxxxx>
CC: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
---
net/ipv4/tcp.c | 4 ++--
net/ipv4/tcp_ipv4.c | 5 +++--
net/ipv4/tcp_output.c | 5 +++--
3 files changed, 8 insertions(+), 6 deletions(-)
--- linux.orig/net/ipv4/tcp_ipv4.c
+++ linux/net/ipv4/tcp_ipv4.c
@@ -970,8 +970,9 @@ static int tcp_v4_parse_md5_keys(struct
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;
@@ -979,7 +980,7 @@ static int tcp_v4_parse_md5_keys(struct
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,
--- linux.orig/net/ipv4/tcp_output.c
+++ linux/net/ipv4/tcp_output.c
@@ -2100,7 +2100,8 @@ void tcp_send_fin(struct sock *sk)
} else {
/* Socket is locked, keep trying until memory is available. */
for (;;) {
- skb = alloc_skb_fclone(MAX_TCP_HEADER, GFP_KERNEL);
+ skb = alloc_skb_fclone(MAX_TCP_HEADER,
+ sk->sk_allocation);
if (skb)
break;
yield();
@@ -2358,7 +2359,7 @@ int tcp_connect(struct sock *sk)
sk->sk_wmem_queued += buff->truesize;
sk_mem_charge(sk, buff->truesize);
tp->packets_out += tcp_skb_pcount(buff);
- tcp_transmit_skb(sk, buff, 1, GFP_KERNEL);
+ tcp_transmit_skb(sk, buff, 1, sk->sk_allocation);
/* We change tp->snd_nxt after the tcp_transmit_skb() call
* in order to make this packet get counted in tcpOutSegs.
--- linux.orig/net/ipv4/tcp.c
+++ linux/net/ipv4/tcp.c
@@ -1834,7 +1834,7 @@ void tcp_close(struct sock *sk, long tim
/* Unread data was tossed, zap the connection. */
NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPABORTONCLOSE);
tcp_set_state(sk, TCP_CLOSE);
- tcp_send_active_reset(sk, GFP_KERNEL);
+ tcp_send_active_reset(sk, sk->sk_allocation);
} else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
/* Check zero linger _after_ checking for unread data. */
sk->sk_prot->disconnect(sk, 0);
@@ -2666,7 +2666,7 @@ static struct tcp_md5sig_pool **__tcp_al
struct tcp_md5sig_pool *p;
struct crypto_hash *hash;
- p = kzalloc(sizeof(*p), GFP_KERNEL);
+ p = kzalloc(sizeof(*p), sk->sk_allocation);
if (!p)
goto out_free;
*per_cpu_ptr(pool, cpu) = p;
--
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