Re: It's back! (Re: [REGRESSION] NFS is creating a hidden port (left over from xs_bind() ))

[Trond Myklebust]

> On Jun 30, 2016, at 11:23, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> 
> On Thu, 30 Jun 2016 13:17:47 +0000
> Trond Myklebust <trondmy@xxxxxxxxxxxxxxx> wrote:
> 
>>> On Jun 30, 2016, at 08:59, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>>> 
>>> [ resending as a new email, as I'm assuming people do not sort their
>>> INBOX via last email on thread, thus my last email is sitting in the
>>> bottom of everyone's INBOX ]
>>> 
>>> I've hit this again. Not sure when it started, but I applied my old
>>> debug trace_printk() patch (attached) and rebooted (4.5.7). I just
>>> tested the latest kernel from Linus's tree (from last nights pull), and
>>> it still gives me the problem.
>>> 
>>> Here's the trace I have:
>>> 
>>>   kworker/3:1H-134   [003] ..s.    61.036129: inet_csk_get_port: snum 805
> 
> Here's were the port is taken
> 
>>>   kworker/3:1H-134   [003] ..s.    61.036135: <stack trace>  
>>> => sched_clock
>>> => inet_addr_type_table
>>> => security_capable
>>> => inet_bind
>>> => xs_bind
>>> => release_sock
>>> => sock_setsockopt
>>> => __sock_create
>>> => xs_create_sock.isra.19
>>> => xs_tcp_setup_socket
>>> => process_one_work
>>> => worker_thread
>>> => worker_thread
>>> => kthread
>>> => ret_from_fork
>>> => kthread    
>>>   kworker/3:1H-134   [003] ..s.    61.036136: inet_bind_hash: add 805
>>>   kworker/3:1H-134   [003] ..s.    61.036138: <stack trace>  
>>> => inet_csk_get_port
>>> => sched_clock
>>> => inet_addr_type_table
>>> => security_capable
>>> => inet_bind
>>> => xs_bind
>>> => release_sock
>>> => sock_setsockopt
>>> => __sock_create
>>> => xs_create_sock.isra.19
>>> => xs_tcp_setup_socket
>>> => process_one_work
>>> => worker_thread
>>> => worker_thread
>>> => kthread
>>> => ret_from_fork
>>> => kthread    
>>>   kworker/3:1H-134   [003] ....    61.036139: xs_bind: RPC:       xs_bind 4.136.255.255:805: ok (0)
> 
> Here's where it is bounded.
> 
>>>   kworker/3:1H-134   [003] ....    61.036140: xs_tcp_setup_socket: RPC:       worker connecting xprt ffff880407eca800 via tcp to 192.168.23.22 (port 43651)
>>>   kworker/3:1H-134   [003] ....    61.036162: xs_tcp_setup_socket: RPC:       ffff880407eca800 connect status 115 connected 0 sock state 2
>>>         <idle>-0     [001] ..s.    61.036450: xs_tcp_state_change: RPC:       xs_tcp_state_change client ffff880407eca800...
>>>         <idle>-0     [001] ..s.    61.036452: xs_tcp_state_change: RPC:       state 1 conn 0 dead 0 zapped 1 sk_shutdown 0
>>>   kworker/1:1H-136   [001] ....    61.036476: xprt_connect_status: RPC:    43 xprt_connect_status: retrying
>>>   kworker/1:1H-136   [001] ....    61.036478: xprt_prepare_transmit: RPC:    43 xprt_prepare_transmit
>>>   kworker/1:1H-136   [001] ....    61.036479: xprt_transmit: RPC:    43 xprt_transmit(72)
>>>   kworker/1:1H-136   [001] ....    61.036486: xs_tcp_send_request: RPC:       xs_tcp_send_request(72) = 0
>>>   kworker/1:1H-136   [001] ....    61.036487: xprt_transmit: RPC:    43 xmit complete
>>>         <idle>-0     [001] ..s.    61.036789: xs_tcp_data_ready: RPC:       xs_tcp_data_ready...
>>>   kworker/1:1H-136   [001] ....    61.036798: xs_tcp_data_recv: RPC:       xs_tcp_data_recv started
>>>   kworker/1:1H-136   [001] ....    61.036799: xs_tcp_data_recv: RPC:       reading TCP record fragment of length 24
>>>   kworker/1:1H-136   [001] ....    61.036799: xs_tcp_data_recv: RPC:       reading XID (4 bytes)
>>>   kworker/1:1H-136   [001] ....    61.036800: xs_tcp_data_recv: RPC:       reading request with XID 2f4c3f88
>>>   kworker/1:1H-136   [001] ....    61.036800: xs_tcp_data_recv: RPC:       reading CALL/REPLY flag (4 bytes)
>>>   kworker/1:1H-136   [001] ....    61.036801: xs_tcp_data_recv: RPC:       read reply XID 2f4c3f88
>>>   kworker/1:1H-136   [001] ..s.    61.036801: xs_tcp_data_recv: RPC:       XID 2f4c3f88 read 16 bytes
>>>   kworker/1:1H-136   [001] ..s.    61.036802: xs_tcp_data_recv: RPC:       xprt = ffff880407eca800, tcp_copied = 24, tcp_offset = 24, tcp_reclen = 24
>>>   kworker/1:1H-136   [001] ..s.    61.036802: xprt_complete_rqst: RPC:    43 xid 2f4c3f88 complete (24 bytes received)
>>>   kworker/1:1H-136   [001] ....    61.036803: xs_tcp_data_recv: RPC:       xs_tcp_data_recv done
>>>   kworker/1:1H-136   [001] ....    61.036812: xprt_release: RPC:    43 release request ffff88040b270800
>>> 
>>> 
>>> # unhide-tcp 
>>> Unhide-tcp 20130526
>>> Copyright  2013 Yago Jesus & Patrick Gouin
>>> License GPLv3+ : GNU GPL version 3 or later
>>> http://www.unhide-forensics.info
>>> Used options: 
>>> [*]Starting TCP checking
>>> 
>>> Found Hidden port that not appears in ss: 805
>>> 
>> 
>> What is a âHidden port that not appears in ss: 805â, and what does this report mean? Are we failing to close a socket?
> 
> I believe hidden ports are ports that are bound to no socket.
> Basically, a "port leak". Where they are in limbo and can never be
> reused.
> 
> I looked at my past report, and everthing is exactly like the issue
> before. When I first boot my box, the port is there, I have the above
> trace. I run netstat -tapn and grep for the port. And it shows that it
> is an established socket between my box and my wife's box (I have a nfs
> mounted file system for her to copy her pictures to my server). After a
> couple of minutes, the port turns from ESTABLISHED to TIME_WAIT, and
> after another minute it disappears. At that moment, the unhide-tcp
> shows the port as hidden.
> 
> When the socket goes away (without releasing the port) I see this in my
> trace:
> 
>    kworker/1:1H-131   [001] ..s.   364.762537: xs_tcp_state_change: RPC:       xs_tcp_state_change client ffff88040ad68800...
>    kworker/1:1H-131   [001] ..s.   364.762539: xs_tcp_state_change: RPC:       state 4 conn 1 dead 0 zapped 1 sk_shutdown 3
>          <idle>-0     [001] ..s.   364.762715: xs_tcp_state_change: RPC:       xs_tcp_state_change client ffff88040ad68800...
>          <idle>-0     [001] ..s.   364.762716: xs_tcp_state_change: RPC:       state 5 conn 0 dead 0 zapped 1 sk_shutdown 3
>          <idle>-0     [001] ..s.   364.762728: xs_tcp_state_change: RPC:       xs_tcp_state_change client ffff88040ad68800...
>          <idle>-0     [001] ..s.   364.762728: xs_tcp_state_change: RPC:       state 7 conn 0 dead 0 zapped 1 sk_shutdown 3
>          <idle>-0     [001] ..s.   364.762729: xprt_disconnect_done: RPC:       disconnected transport ffff88040ad68800
>          <idle>-0     [001] ..s.   364.762730: xs_tcp_state_change: RPC:       xs_tcp_state_change client ffff88040ad68800...
>          <idle>-0     [001] ..s.   364.762730: xs_tcp_state_change: RPC:       state 7 conn 0 dead 0 zapped 1 sk_shutdown 3
>          <idle>-0     [001] ..s.   364.762730: xprt_disconnect_done: RPC:       disconnected transport ffff88040ad68800
> 
> I can add more trace_printk()s if it would help.


Wait. So the NFS mount is still active, itâs just that the socket disconnected due to no traffic? That should be OK. Granted that the port canât be reused by another process, but you really donât want that: what if there are no other ports available and you start writing to a file on the NFS partition?

Cheers
  Trond