WARNING: CPU: 0 PID: 0 at net/ipv4/af_inet.c:155 inet_sock_destruct+0x1c4/0x1dc

[Eric Dumazet]

On Tue, 2016-07-12 at 11:53 +0200, Mason wrote:
> On 05/07/2016 17:28, Florian Fainelli wrote:
> 
> > Le 05/07/2016 07:50, Mason wrote:
> > 
> >> On 05/07/2016 15:33, Mason wrote:
> >> 
> >>> I was testing suspend/resume sequences where the suspend operation
> >>> fails and returns without having suspended the platform.
> 
> Please forget I ever mentioned suspend, that was a red herring.
> The warning is displayed even if I never suspend.
> (Dropping linux-pm from this discussion.)
> 
> >> I rebooted, tried the same operation, and hit the same warning
> >> still 310 seconds later:
> 
> However, the 310 seconds time span still seems to be relevant.
> 
> Steps to reproduce: I booted the system, logged in as root,
> mounted an NFS file system, then left the system idling at
> the prompt.
> 
> (I don't remember seeing this warning in v4.1 and v4.4)
> 
> What's going wrong here? Is it related to NFS?
> 
> Here is the defconfig I'm using
> http://pastebin.ubuntu.com/19160299/
> 
> Regards.
> 

Could you try this debug patch ?

diff --git a/net/core/sock.c b/net/core/sock.c
index b7f12639c26a..7fb1aeadbda7 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1465,6 +1465,7 @@ static void __sk_destruct(struct rcu_head *head)
 
 void sk_destruct(struct sock *sk)
 {
+	WARN_ON_ONCE(sk->sk_forward_alloc);
 	if (sock_flag(sk, SOCK_RCU_FREE))
 		call_rcu(&sk->sk_rcu, __sk_destruct);
 	else