From: Chuck Lever <chuck.lever@oracle.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Andy Chittenden <andyc@bluearc.com>,
"Linux Kernel Mailing List (linux-kernel@vger.kernel.org)"
<linux-kernel@vger.kernel.org>,
Trond Myklebust <trond.myklebust@fys.uio.no>,
netdev <netdev@vger.kernel.org>,
Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Subject: Re: nfs client hang
Date: Tue, 27 Jul 2010 13:28:44 -0400 [thread overview]
Message-ID: <4C4F174C.2000308@oracle.com> (raw)
In-Reply-To: <1280233276.2827.175.camel@edumazet-laptop>
Add CC: linux-nfs@vger.kernel.org
On 07/27/10 08:21 AM, Eric Dumazet wrote:
> Le mardi 27 juillet 2010 à 11:53 +0100, Andy Chittenden a écrit :
>>>>> IE the client starts a connection and then closes it again without sending data.
>>>> Once this happens, here's some rpcdebug info for the rpc module using 2.6.34.1 kernel:
>>>>
>>>> ... lots of the following nfsv3 WRITE requests:
>>>> [ 7670.026741] 57793 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7670.026759] 57794 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7670.026778] 57795 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7670.026797] 57796 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7670.026815] 57797 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7670.026834] 57798 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7670.026853] 57799 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7670.026871] 57800 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7670.026890] 57801 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7670.026909] 57802 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7680.520042] RPC: worker connecting xprt ffff88013e62d800 via tcp to 10.1.6.102 (port 2049)
>>>> [ 7680.520066] RPC: ffff88013e62d800 connect status 99 connected 0 sock state 7
>>>> [ 7680.520074] RPC: 33550 __rpc_wake_up_task (now 4296812426)
>>>> [ 7680.520079] RPC: 33550 disabling timer
>>>> [ 7680.520084] RPC: 33550 removed from queue ffff88013e62db20 "xprt_pending"
>>>> [ 7680.520089] RPC: __rpc_wake_up_task done
>>>> [ 7680.520094] RPC: 33550 __rpc_execute flags=0x1
>>>> [ 7680.520098] RPC: 33550 xprt_connect_status: retrying
>>>> [ 7680.520103] RPC: 33550 call_connect_status (status -11)
>>>> [ 7680.520108] RPC: 33550 call_transmit (status 0)
>>>> [ 7680.520112] RPC: 33550 xprt_prepare_transmit
>>>> [ 7680.520118] RPC: 33550 rpc_xdr_encode (status 0)
>>>> [ 7680.520123] RPC: 33550 marshaling UNIX cred ffff88012e002300
>>>> [ 7680.520130] RPC: 33550 using AUTH_UNIX cred ffff88012e002300 to wrap rpc data
>>>> [ 7680.520136] RPC: 33550 xprt_transmit(32920)
>>>> [ 7680.520145] RPC: xs_tcp_send_request(32920) = -32
>>>> [ 7680.520151] RPC: xs_tcp_state_change client ffff88013e62d800...
>>>> [ 7680.520156] RPC: state 7 conn 0 dead 0 zapped 1
>>
>>> I changed that debug to output sk_shutdown too. That has a value of 2
>>> (IE SEND_SHUTDOWN). Looking at tcp_sendmsg(), I see this:
>>
>>> err = -EPIPE;
>>> if (sk->sk_err || (sk->sk_shutdown& SEND_SHUTDOWN))
>>> goto out_err;
>>
>>> which correlates with the trace "xs_tcp_send_request(32920) = -32". So,
>>> this looks like a problem in the sockets/tcp layer. The rpc layer issues
>>> a shutdown and then reconnects using the same socket. So either
>>> sk_shutdown needs zeroing once the shutdown completes or should be
>>> zeroed on subsequent connect. The latter sounds safer.
>> This patch for 2.6.34.1 fixes the issue:
>>
>> --- /home/company/software/src/linux-2.6.34.1/net/ipv4/tcp_output.c 2010-07-27 08:46:46.917000000 +0100
>> +++ net/ipv4/tcp_output.c 2010-07-27 09:19:16.000000000 +0100
>> @@ -2522,6 +2522,13 @@
>> struct tcp_sock *tp = tcp_sk(sk);
>> __u8 rcv_wscale;
>>
>> + /* clear down any previous shutdown attempts so that
>> + * reconnects on a socket that's been shutdown leave the
>> + * socket in a usable state (otherwise tcp_sendmsg() returns
>> + * -EPIPE).
>> + */
>> + sk->sk_shutdown = 0;
>> +
>> /* We'll fix this up when we get a response from the other end.
>> * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT.
>> */
>>
>> As I mentioned in my first message, we first saw this issue in 2.6.32 as supplied by debian (linux-image-2.6.32-5-amd64 Version: 2.6.32-17). It looks like the same patch would fix the problem there too.
>>
>
> CC netdev
>
> This reminds me a similar problem we had in the past, fixed with commit
> 1fdf475a (tcp: tcp_disconnect() should clear window_clamp)
>
> But tcp_disconnect() already clears sk->sk_shutdown
>
> If NFS calls tcp_disconnect(), then shutdown(), there is a problem.
If tcp_disconnect() was called at some point, I would expect to see a
message from xs_error_report() in the debugging output. Perhaps
tcp_disconnect() is not being invoked at all?
> Maybe xs_tcp_shutdown() should make some sanity tests ?
>
> Following sequence is legal, and your patch might break it.
>
> fd = socket(...);
> shutdown(fd, SHUT_WR);
> ...
> connect(fd, ...);
I looked closely at some of Andy's debugging output from the
linux-kernel mailing list archive. I basically agree that the network
layer is returning -EPIPE from tcp_sendmsg(), which the RPC client logic
does not expect. But it's not clear to me how it gets into this state.
> [ 7728.520042] RPC: worker connecting xprt ffff88013e62d800 via tcp to 10.1.6.102 (port 2049)
> [ 7728.520093] RPC: ffff88013e62d800 connect status 115
connected 0 sock state 2
"sock state 2" => sk->sk_state == TCP_SYN_SENT
> [ 7728.520884] RPC: xs_tcp_state_change client ffff88013e62d800...
> [ 7728.520889] RPC: state 1 conn 0 dead 0 zapped 1
"state 1" => sk->sk_state == TCP_ESTABLISHED
RPC client wakes up this RPC task now that the connection is established.
> [ 7728.520896] RPC: 33550 __rpc_wake_up_task (now 4296824426)
> [ 7728.520900] RPC: 33550 disabling timer
> [ 7728.520906] RPC: 33550 removed from queue ffff88013e62db20 "xprt_pending"
> [ 7728.520912] RPC: __rpc_wake_up_task done
> [ 7728.520932] RPC: 33550 __rpc_execute flags=0x1
> [ 7728.520937] RPC: 33550 xprt_connect_status: retrying
> [ 7728.520942] RPC: 33550 call_connect_status (status -11)
The awoken RPC task's status is -EAGAIN, which prevents a reconnection
attempt.
> [ 7728.520947] RPC: 33550 call_transmit (status 0)
> [ 7728.520951] RPC: 33550 xprt_prepare_transmit
> [ 7728.520957] RPC: 33550 rpc_xdr_encode (status 0)
> [ 7728.520962] RPC: 33550 marshaling UNIX cred ffff88012e002300
> [ 7728.520969] RPC: 33550 using AUTH_UNIX cred ffff88012e002300 to wrap rpc data
> [ 7728.520976] RPC: 33550 xprt_transmit(32920)
RPC client encodes the request and attempts to send it.
> [ 7728.520984] RPC: xs_tcp_send_request(32920) = -32
Network layer says -EPIPE, for some reason. RPC client calls
kernel_sock_shutdown(SHUT_WR).
> [ 7728.520997] RPC: xs_tcp_state_change client ffff88013e62d800...
> [ 7728.521007] RPC: state 4 conn 1 dead 0 zapped 1
"state 4" => sk->sk_state == TCP_FIN_WAIT1
The RPC client sets up a linger timeout.
> [ 7728.521013] RPC: 33550 call_status (status -32)
> [ 7728.521018] RPC: 33550 call_bind (status 0)
> [ 7728.521023] RPC: 33550 call_connect xprt ffff88013e62d800 is not connected
> [ 7728.521028] RPC: 33550 xprt_connect xprt ffff88013e62d800 is not connected
> [ 7728.521035] RPC: 33550 sleep_on(queue "xprt_pending" time 4296824426)
> [ 7728.521040] RPC: 33550 added to queue ffff88013e62db20 "xprt_pending"
> [ 7728.521045] RPC: 33550 setting alarm for 60000 ms
RPC client puts this RPC task to sleep.
> [ 7728.521439] RPC: xs_tcp_state_change client ffff88013e62d800...
> [ 7728.521444] RPC: state 5 conn 0 dead 0 zapped 1
"state 5" => sk->sk_state == TCP_FIN_WAIT2
> [ 7728.521602] RPC: xs_tcp_state_change client ffff88013e62d800...
> [ 7728.521608] RPC: state 7 conn 0 dead 0 zapped 1
> [ 7728.521612] RPC: disconnected transport ffff88013e62d800
"state 7" => sk->sk_state == TCP_CLOSE
The RPC client marks the socket closed. and the linger timeout is
cancelled. At this point, sk_shutdown should be set to zero, correct?
I don't see an xs_error_report() call here, which would confirm that the
socket took a trip through tcp_disconnect().
> [ 7728.521617] RPC: 33550 __rpc_wake_up_task (now 4296824426)
> [ 7728.521621] RPC: 33550 disabling timer
> [ 7728.521626] RPC: 33550 removed from queue ffff88013e62db20 "xprt_pending"
> [ 7728.521631] RPC: __rpc_wake_up_task done
RPC client wakes up the RPC task. Meanwhile...
> [ 7728.521636] RPC: xs_tcp_state_change client ffff88013e62d800...
> [ 7728.521641] RPC: state 7 conn 0 dead 0 zapped 1
> [ 7728.521645] RPC: disconnected transport ffff88013e62d800
> [ 7728.521649] RPC: xs_tcp_data_ready...
... network layer calls closed socket's data_ready method... while the
awoken RPC task gets underway.
> [ 7728.521662] RPC: 33550 __rpc_execute flags=0x1
> [ 7728.521666] RPC: 33550 xprt_connect_status: retrying
> [ 7728.521671] RPC: 33550 call_connect_status (status -11)
The awoken RPC task's status is -EAGAIN, which prevents a reconnection
attempt, even though there is no established connection.
RPC client barrels on to send the request again.
> [ 7728.521675] RPC: 33550 call_transmit (status 0)
> [ 7728.521679] RPC: 33550 xprt_prepare_transmit
> [ 7728.521683] RPC: 33550 rpc_xdr_encode (status 0)
> [ 7728.521688] RPC: 33550 marshaling UNIX cred ffff88012e002300
> [ 7728.521694] RPC: 33550 using AUTH_UNIX cred ffff88012e002300 to wrap rpc data
> [ 7728.521699] RPC: 33550 xprt_transmit(32920)
> [ 7728.521704] RPC: xs_tcp_send_request(32920) = -32
RPC client attempts to send again, gets -EPIPE, and calls
kernel_sock_shutdown(SHUT_WR). If there is no connection established,
the RPC client expects -ENOTCONN, in which case it will attempt to
reconnect here.
> [ 7728.521709] RPC: xs_tcp_state_change client ffff88013e62d800...
> [ 7728.521714] RPC: state 7 conn 0 dead 0 zapped 1
> [ 7728.521718] RPC: disconnected transport ffff88013e62d800
"state 7" => sk->sk_state == TCP_CLOSE
Following this, the RPC client attempts to retransmit the request
repeatedly, but the socket remains in the TCP_CLOSE state.
WARNING: multiple messages have this Message-ID (diff)
From: Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
To: Eric Dumazet <eric.dumazet-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Andy Chittenden <andyc-Pe6u2o1+k2hBDgjK7y7TUQ@public.gmane.org>,
"Linux Kernel Mailing List
(linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org)"
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Trond Myklebust
<trond.myklebust-41N18TsMXrtuMpJDpNschA@public.gmane.org>,
netdev <netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Linux NFS Mailing List
<linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: nfs client hang
Date: Tue, 27 Jul 2010 13:28:44 -0400 [thread overview]
Message-ID: <4C4F174C.2000308@oracle.com> (raw)
In-Reply-To: <1280233276.2827.175.camel@edumazet-laptop>
Add CC: linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
On 07/27/10 08:21 AM, Eric Dumazet wrote:
> Le mardi 27 juillet 2010 à 11:53 +0100, Andy Chittenden a écrit :
>>>>> IE the client starts a connection and then closes it again without sending data.
>>>> Once this happens, here's some rpcdebug info for the rpc module using 2.6.34.1 kernel:
>>>>
>>>> ... lots of the following nfsv3 WRITE requests:
>>>> [ 7670.026741] 57793 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7670.026759] 57794 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7670.026778] 57795 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7670.026797] 57796 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7670.026815] 57797 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7670.026834] 57798 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7670.026853] 57799 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7670.026871] 57800 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7670.026890] 57801 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7670.026909] 57802 0001 -11 ffff88012e32b000 (null) 0 ffffffffa03beb10 nfsv3 WRITE a:call_reserveresult q:xprt_backlog
>>>> [ 7680.520042] RPC: worker connecting xprt ffff88013e62d800 via tcp to 10.1.6.102 (port 2049)
>>>> [ 7680.520066] RPC: ffff88013e62d800 connect status 99 connected 0 sock state 7
>>>> [ 7680.520074] RPC: 33550 __rpc_wake_up_task (now 4296812426)
>>>> [ 7680.520079] RPC: 33550 disabling timer
>>>> [ 7680.520084] RPC: 33550 removed from queue ffff88013e62db20 "xprt_pending"
>>>> [ 7680.520089] RPC: __rpc_wake_up_task done
>>>> [ 7680.520094] RPC: 33550 __rpc_execute flags=0x1
>>>> [ 7680.520098] RPC: 33550 xprt_connect_status: retrying
>>>> [ 7680.520103] RPC: 33550 call_connect_status (status -11)
>>>> [ 7680.520108] RPC: 33550 call_transmit (status 0)
>>>> [ 7680.520112] RPC: 33550 xprt_prepare_transmit
>>>> [ 7680.520118] RPC: 33550 rpc_xdr_encode (status 0)
>>>> [ 7680.520123] RPC: 33550 marshaling UNIX cred ffff88012e002300
>>>> [ 7680.520130] RPC: 33550 using AUTH_UNIX cred ffff88012e002300 to wrap rpc data
>>>> [ 7680.520136] RPC: 33550 xprt_transmit(32920)
>>>> [ 7680.520145] RPC: xs_tcp_send_request(32920) = -32
>>>> [ 7680.520151] RPC: xs_tcp_state_change client ffff88013e62d800...
>>>> [ 7680.520156] RPC: state 7 conn 0 dead 0 zapped 1
>>
>>> I changed that debug to output sk_shutdown too. That has a value of 2
>>> (IE SEND_SHUTDOWN). Looking at tcp_sendmsg(), I see this:
>>
>>> err = -EPIPE;
>>> if (sk->sk_err || (sk->sk_shutdown& SEND_SHUTDOWN))
>>> goto out_err;
>>
>>> which correlates with the trace "xs_tcp_send_request(32920) = -32". So,
>>> this looks like a problem in the sockets/tcp layer. The rpc layer issues
>>> a shutdown and then reconnects using the same socket. So either
>>> sk_shutdown needs zeroing once the shutdown completes or should be
>>> zeroed on subsequent connect. The latter sounds safer.
>> This patch for 2.6.34.1 fixes the issue:
>>
>> --- /home/company/software/src/linux-2.6.34.1/net/ipv4/tcp_output.c 2010-07-27 08:46:46.917000000 +0100
>> +++ net/ipv4/tcp_output.c 2010-07-27 09:19:16.000000000 +0100
>> @@ -2522,6 +2522,13 @@
>> struct tcp_sock *tp = tcp_sk(sk);
>> __u8 rcv_wscale;
>>
>> + /* clear down any previous shutdown attempts so that
>> + * reconnects on a socket that's been shutdown leave the
>> + * socket in a usable state (otherwise tcp_sendmsg() returns
>> + * -EPIPE).
>> + */
>> + sk->sk_shutdown = 0;
>> +
>> /* We'll fix this up when we get a response from the other end.
>> * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT.
>> */
>>
>> As I mentioned in my first message, we first saw this issue in 2.6.32 as supplied by debian (linux-image-2.6.32-5-amd64 Version: 2.6.32-17). It looks like the same patch would fix the problem there too.
>>
>
> CC netdev
>
> This reminds me a similar problem we had in the past, fixed with commit
> 1fdf475a (tcp: tcp_disconnect() should clear window_clamp)
>
> But tcp_disconnect() already clears sk->sk_shutdown
>
> If NFS calls tcp_disconnect(), then shutdown(), there is a problem.
If tcp_disconnect() was called at some point, I would expect to see a
message from xs_error_report() in the debugging output. Perhaps
tcp_disconnect() is not being invoked at all?
> Maybe xs_tcp_shutdown() should make some sanity tests ?
>
> Following sequence is legal, and your patch might break it.
>
> fd = socket(...);
> shutdown(fd, SHUT_WR);
> ...
> connect(fd, ...);
I looked closely at some of Andy's debugging output from the
linux-kernel mailing list archive. I basically agree that the network
layer is returning -EPIPE from tcp_sendmsg(), which the RPC client logic
does not expect. But it's not clear to me how it gets into this state.
> [ 7728.520042] RPC: worker connecting xprt ffff88013e62d800 via tcp to 10.1.6.102 (port 2049)
> [ 7728.520093] RPC: ffff88013e62d800 connect status 115
connected 0 sock state 2
"sock state 2" => sk->sk_state == TCP_SYN_SENT
> [ 7728.520884] RPC: xs_tcp_state_change client ffff88013e62d800...
> [ 7728.520889] RPC: state 1 conn 0 dead 0 zapped 1
"state 1" => sk->sk_state == TCP_ESTABLISHED
RPC client wakes up this RPC task now that the connection is established.
> [ 7728.520896] RPC: 33550 __rpc_wake_up_task (now 4296824426)
> [ 7728.520900] RPC: 33550 disabling timer
> [ 7728.520906] RPC: 33550 removed from queue ffff88013e62db20 "xprt_pending"
> [ 7728.520912] RPC: __rpc_wake_up_task done
> [ 7728.520932] RPC: 33550 __rpc_execute flags=0x1
> [ 7728.520937] RPC: 33550 xprt_connect_status: retrying
> [ 7728.520942] RPC: 33550 call_connect_status (status -11)
The awoken RPC task's status is -EAGAIN, which prevents a reconnection
attempt.
> [ 7728.520947] RPC: 33550 call_transmit (status 0)
> [ 7728.520951] RPC: 33550 xprt_prepare_transmit
> [ 7728.520957] RPC: 33550 rpc_xdr_encode (status 0)
> [ 7728.520962] RPC: 33550 marshaling UNIX cred ffff88012e002300
> [ 7728.520969] RPC: 33550 using AUTH_UNIX cred ffff88012e002300 to wrap rpc data
> [ 7728.520976] RPC: 33550 xprt_transmit(32920)
RPC client encodes the request and attempts to send it.
> [ 7728.520984] RPC: xs_tcp_send_request(32920) = -32
Network layer says -EPIPE, for some reason. RPC client calls
kernel_sock_shutdown(SHUT_WR).
> [ 7728.520997] RPC: xs_tcp_state_change client ffff88013e62d800...
> [ 7728.521007] RPC: state 4 conn 1 dead 0 zapped 1
"state 4" => sk->sk_state == TCP_FIN_WAIT1
The RPC client sets up a linger timeout.
> [ 7728.521013] RPC: 33550 call_status (status -32)
> [ 7728.521018] RPC: 33550 call_bind (status 0)
> [ 7728.521023] RPC: 33550 call_connect xprt ffff88013e62d800 is not connected
> [ 7728.521028] RPC: 33550 xprt_connect xprt ffff88013e62d800 is not connected
> [ 7728.521035] RPC: 33550 sleep_on(queue "xprt_pending" time 4296824426)
> [ 7728.521040] RPC: 33550 added to queue ffff88013e62db20 "xprt_pending"
> [ 7728.521045] RPC: 33550 setting alarm for 60000 ms
RPC client puts this RPC task to sleep.
> [ 7728.521439] RPC: xs_tcp_state_change client ffff88013e62d800...
> [ 7728.521444] RPC: state 5 conn 0 dead 0 zapped 1
"state 5" => sk->sk_state == TCP_FIN_WAIT2
> [ 7728.521602] RPC: xs_tcp_state_change client ffff88013e62d800...
> [ 7728.521608] RPC: state 7 conn 0 dead 0 zapped 1
> [ 7728.521612] RPC: disconnected transport ffff88013e62d800
"state 7" => sk->sk_state == TCP_CLOSE
The RPC client marks the socket closed. and the linger timeout is
cancelled. At this point, sk_shutdown should be set to zero, correct?
I don't see an xs_error_report() call here, which would confirm that the
socket took a trip through tcp_disconnect().
> [ 7728.521617] RPC: 33550 __rpc_wake_up_task (now 4296824426)
> [ 7728.521621] RPC: 33550 disabling timer
> [ 7728.521626] RPC: 33550 removed from queue ffff88013e62db20 "xprt_pending"
> [ 7728.521631] RPC: __rpc_wake_up_task done
RPC client wakes up the RPC task. Meanwhile...
> [ 7728.521636] RPC: xs_tcp_state_change client ffff88013e62d800...
> [ 7728.521641] RPC: state 7 conn 0 dead 0 zapped 1
> [ 7728.521645] RPC: disconnected transport ffff88013e62d800
> [ 7728.521649] RPC: xs_tcp_data_ready...
... network layer calls closed socket's data_ready method... while the
awoken RPC task gets underway.
> [ 7728.521662] RPC: 33550 __rpc_execute flags=0x1
> [ 7728.521666] RPC: 33550 xprt_connect_status: retrying
> [ 7728.521671] RPC: 33550 call_connect_status (status -11)
The awoken RPC task's status is -EAGAIN, which prevents a reconnection
attempt, even though there is no established connection.
RPC client barrels on to send the request again.
> [ 7728.521675] RPC: 33550 call_transmit (status 0)
> [ 7728.521679] RPC: 33550 xprt_prepare_transmit
> [ 7728.521683] RPC: 33550 rpc_xdr_encode (status 0)
> [ 7728.521688] RPC: 33550 marshaling UNIX cred ffff88012e002300
> [ 7728.521694] RPC: 33550 using AUTH_UNIX cred ffff88012e002300 to wrap rpc data
> [ 7728.521699] RPC: 33550 xprt_transmit(32920)
> [ 7728.521704] RPC: xs_tcp_send_request(32920) = -32
RPC client attempts to send again, gets -EPIPE, and calls
kernel_sock_shutdown(SHUT_WR). If there is no connection established,
the RPC client expects -ENOTCONN, in which case it will attempt to
reconnect here.
> [ 7728.521709] RPC: xs_tcp_state_change client ffff88013e62d800...
> [ 7728.521714] RPC: state 7 conn 0 dead 0 zapped 1
> [ 7728.521718] RPC: disconnected transport ffff88013e62d800
"state 7" => sk->sk_state == TCP_CLOSE
Following this, the RPC client attempts to retransmit the request
repeatedly, but the socket remains in the TCP_CLOSE state.
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next prev parent reply other threads:[~2010-07-27 17:29 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <99613C19B13C5D40914FB8930657FA9303365708DE@uk-ex-mbx1.terastack.bluearc.com>
2010-07-27 7:25 ` nfs client hang Andy Chittenden
2010-07-27 10:53 ` Andy Chittenden
2010-07-27 12:21 ` Eric Dumazet
2010-07-27 12:51 ` Andy Chittenden
2010-07-27 17:28 ` Chuck Lever [this message]
2010-07-27 17:28 ` Chuck Lever
2010-07-28 7:08 ` Andy Chittenden
2010-07-28 7:08 ` Andy Chittenden
2010-07-28 7:08 ` Andy Chittenden
2010-07-28 7:24 ` Andy Chittenden
2010-07-28 7:24 ` Andy Chittenden
2010-07-28 7:24 ` Andy Chittenden
2010-07-28 17:37 ` Chuck Lever
2010-07-28 17:37 ` Chuck Lever
2010-07-29 10:10 ` Andy Chittenden
2010-07-29 10:10 ` Andy Chittenden
2011-07-07 17:01 ` General Linux Kernel / User Space License Mitchell Erblich
2011-07-07 20:35 ` Chris Friesen
2010-07-23 12:36 nfs client hang Andy Chittenden
-- strict thread matches above, loose matches on Subject: below --
2010-07-22 12:19 Andy Chittenden
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