On Mon, 2013-01-07 at 12:25 +0000, Mel Gorman wrote:

quoted

===> 28014[28017]/stack <===
[<ffffffff8129fc1d>] release_sock+0xe5/0x11b
[<ffffffff812a642c>] sk_stream_wait_memory+0x1f7/0x1fc
[<ffffffff81040d5e>] autoremove_wake_function+0x0/0x2a
[<ffffffff812d8fc3>] tcp_sendmsg+0x710/0x86d
[<ffffffff8129a33e>] sock_sendmsg+0x7b/0x93
[<ffffffff8129a642>] sys_sendto+0xee/0x145
[<ffffffff8129a3bc>] sockfd_lookup_light+0x1a/0x50
[<ffffffff8129a668>] sys_sendto+0x114/0x145
[<ffffffff81000e34>] __switch_to+0x235/0x3c5
[<ffffffff81322769>] system_call_fastpath+0x16/0x1b
[<ffffffffffffffff>] 0xffffffffffffffff

This seems to be the guy that's stuck. It's waiting for more memory for
the socket but who or what is allocating that memory? There are a few other
bugs from over the weekend that I want to take a look at so I did not dig
further or try to reproduce this bug yet. I'm adding Eric Dumazet back to
the cc in case he has the quick answer.

Thanks Mel

It would not surprise me if sk_stream_wait_memory() have plain bug(s) or
race(s).

In 2010, in commit 482964e56e132 Nagendra Tomar fixed a pretty severe
long standing bug.

This path is not taken very often on most machines.

I would try the following patch :

diff --git a/net/core/stream.c b/net/core/stream.c
index f5df85d..6f09979 100644
--- a/net/core/stream.c
+++ b/net/core/stream.c

@@ -126,6 +126,7 @@ int sk_stream_wait_memory(struct sock *sk, long *timeo_p)
 
 	while (1) {
 		set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
+		set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 
 		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
 

@@ -139,7 +140,6 @@ int sk_stream_wait_memory(struct sock *sk, long *timeo_p)
 		if (sk_stream_memory_free(sk) && !vm_wait)
 			break;
 
-		set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 		sk->sk_write_pending++;
 		sk_wait_event(sk, &current_timeo, sk->sk_err ||
 						  (sk->sk_shutdown & SEND_SHUTDOWN) ||




--

To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>