Hi John,

Do you have several tipc clients subscribed to topology server?
What subscription timeout do they use?

Please enable kernel command line parameter:
softlockup_all_cpu_backtrace=1

/Partha

On 11/23/2016 11:04 PM, John Thompson wrote:
> Hi Partha,
>
> I tested overnight with the 2 patches you provided yesterday.
> Testing is still showing problems, here is one of the soft lockups, the
> other is the same as I sent the other day.
> I am going to redo my build as I expected some change in behaviour with
> your patches.
>
> It is possible that I am doing some dumping of nodes or links as I am
> not certain of all the code or paths.
> I have found that we do a tipc-config -nt and tipc-config -ls in some
> situations but it shouldn 't be initiated in this
> reboot case.
>
> <0>NMI watchdog: BUG: soft lockup - CPU#3 stuck for 22s! [pimd:1220]
> <0>NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [rpc.13:2419]
> <6>Modules linked in:
> <0>NMI watchdog: BUG: soft lockup - CPU#2 stuck for 22s! [AIS listener:1600]
> <6> tipc
> <6>Modules linked in:
> <6> jitterentropy_rng
> <6> tipc
> <6> echainiv
> <6> jitterentropy_rng
> <6> drbg
> <6> echainiv
> <6> platform_driver(O)
> <6> drbg
> <6> platform_driver(O)
> <6>
> <6>CPU: 0 PID: 2419 Comm: rpc.13 Tainted: P           O
> <6>CPU: 2 PID: 1600 Comm: AIS listener Tainted: P           O
> <6>task: aed76d20 ti: ae70c000 task.ti: ae70c000
> <6>task: aee3ced0 ti: ae686000 task.ti: ae686000
> <6>NIP: 8069257c LR: c13ebc4c CTR: 80692540
> <6>NIP: 80692578 LR: c13ebf50 CTR: 80692540
> <6>REGS: ae70dc20 TRAP: 0901   Tainted: P           O
> <6>REGS: ae687ad0 TRAP: 0901   Tainted: P           O
> <6>MSR: 00029002
> <6>MSR: 00029002
> <6><
> <6><
> <6>CE
> <6>CE
> <6>,EE
> <6>,EE
> <6>,ME
> <6>,ME
> <6>>
> <6>>
> <6>  CR: 42002484  XER: 20000000
> <6>  CR: 48002444  XER: 00000000
> <6>
> <6>GPR00:
> <6>
> <6>GPR00:
> <6>c13f3c34
> <6>c13ea408
> <6>ae70dcd0
> <6>ae687b80
> <6>aed76d20
> <6>aee3ced0
> <6>ae55c8ec
> <6>ae55c8ec
> <6>00002711
> <6>00000000
> <6>00000005
> <6>a30e7264
> <6>8666592a
> <6>ae5e070c
> <6>8666592b
> <6>fffffffd
> <6>
> <6>GPR08:
> <6>
> <6>GPR08:
> <6>ae9dad20
> <6>ae72fbc8
> <6>00000001
> <6>00000001
> <6>00000001
> <6>00000001
> <6>00000000
> <6>00000004
> <6>80692540
> <6>80692540
> <6>
> <6>
> <6>NIP [8069257c] _raw_spin_lock_bh+0x3c/0x70
> <6>NIP [80692578] _raw_spin_lock_bh+0x38/0x70
> <6>LR [c13ebc4c] tipc_nametbl_withdraw+0x4c/0x140 [tipc]
> <6>LR [c13ebf50] tipc_nametbl_unsubscribe+0x50/0x120 [tipc]
> <6>Call Trace:
> <6>Call Trace:
> <6>[ae70dcd0] [a85d99a0] 0xa85d99a0
> <6>[ae687b80] [800fa258] check_object+0xc8/0x270
> <6> (unreliable)
> <6> (unreliable)
> <6>
> <6>
> <6>[ae70dd00] [c13f3c34] tipc_nl_node_dump_link+0x1904/0x45d0 [tipc]
> <6>[ae687ba0] [c13ea408] tipc_named_reinit+0xf8/0x820 [tipc]
> <6>
> <6>
> <6>[ae70dd30] [c13f4848] tipc_nl_node_dump_link+0x2518/0x45d0 [tipc]
> <6>[ae687bb0] [c13ea6c0] tipc_named_reinit+0x3b0/0x820 [tipc]
> <6>
> <6>
> <6>[ae70dd70] [804f29e0] sock_release+0x30/0xf0
> <6>[ae687bd0] [c13f7bbc] tipc_nl_publ_dump+0x50c/0xed0 [tipc]
> <6>
> <6>
> <6>[ae70dd80] [804f2ab4] sock_close+0x14/0x30
> <6>[ae687c00] [c13f865c] tipc_conn_sendmsg+0xdc/0x170 [tipc]
> <6>
> <6>
> <6>[ae70dd90] [80105844] __fput+0x94/0x200
> <6>[ae687c30] [c13eacbc] tipc_subscrp_report_overlap+0xbc/0xd0 [tipc]
> <6>
> <6>
> <6>[ae70ddb0] [8003dca4] task_work_run+0xd4/0x100
> <6>[ae687c70] [c13eb27c] tipc_topsrv_stop+0x45c/0x4f0 [tipc]
> <6>
> <6>
> <6>[ae70ddd0] [80023620] do_exit+0x280/0x980
> <6>[ae687ca0] [c13eb7a8] tipc_nametbl_remove_publ+0x58/0x110 [tipc]
> <6>
> <6>
> <6>[ae70de10] [80024c48] do_group_exit+0x48/0xb0
> <6>[ae687cd0] [c13ebc68] tipc_nametbl_withdraw+0x68/0x140 [tipc]
> <6>
> <6>
> <6>[ae70de30] [80030344] get_signal+0x244/0x4f0
> <6>[ae687d00] [c13f3c34] tipc_nl_node_dump_link+0x1904/0x45d0 [tipc]
> <6>
> <6>
> <6>[ae70de80] [80007734] do_signal+0x34/0x1c0
> <6>[ae687d30] [c13f4848] tipc_nl_node_dump_link+0x2518/0x45d0 [tipc]
> <6>
> <6>
> <6>[ae70df30] [800079a8] do_notify_resume+0x68/0x80
> <6>[ae687d70] [804f29e0] sock_release+0x30/0xf0
> <6>
> <6>
> <6>[ae70df40] [8000fa1c] do_user_signal+0x74/0xc4
> <6>[ae687d80] [804f2ab4] sock_close+0x14/0x30
> <6>
> <6>
> <6>--- interrupt: c00 at 0xfe490c4
> <6>    LR = 0xfe490a0
> <6>[ae687d90] [80105844] __fput+0x94/0x200
> <6>Instruction dump:
> <6>
> <6>
> <6>[ae687db0] [8003dca4] task_work_run+0xd4/0x100
> <6>912a0008
> <6>
> <6>39400001
> <6>[ae687dd0] [80023620] do_exit+0x280/0x980
> <6>7d201828
> <6>
> <6>2c090000
> <6>[ae687e10] [80024c48] do_group_exit+0x48/0xb0
> <6>40820010
> <6>
> <6>7d40192d
> <6>[ae687e30] [80030344] get_signal+0x244/0x4f0
> <6>40a2fff0
> <6>
> <6>7c2004ac
> <6>[ae687e80] [80007734] do_signal+0x34/0x1c0
> <6>
> <6>
> <6>2f890000
> <6>[ae687f30] [800079a8] do_notify_resume+0x68/0x80
> <6>4dbe0020
> <6>
> <6>7c210b78
> <6>[ae687f40] [8000fa1c] do_user_signal+0x74/0xc4
> <6>81230000
> <6>
> <6><2f890000>
> <6>--- interrupt: c00 at 0xf4f3d08
> <6>    LR = 0xf4f3ce8
> <6>40befff4
> <6>Instruction dump:
> <6>7c421378
> <6>
> <6>7d201828
> <6>39290200
> <6>
> <6>912a0008 39400001
> <0>Kernel panic - not syncing: softlockup: hung tasks
> <6>7d201828
> <6>CPU: 0 PID: 2419 Comm: rpc.13 Tainted: P           O L
> <6>2c090000
> <6>Call Trace:
> <6>40820010
> <6>[ae70da80] [80694e20] dump_stack+0x84/0xb0
> <6>7d40192d
> <6> (unreliable)
> <6>40a2fff0
> <6>
> <6>
> <6>[ae70da90] [80692ca8] panic+0xd8/0x214
> <6>7c2004ac
> <6>
> <6>2f890000
> <6>[ae70daf0] [800a0258] watchdog_timer_fn+0x2d8/0x2e0
> <6>4dbe0020
> <6>
> <6>7c210b78
> <6>[ae70db40] [8007ae58] __hrtimer_run_queues+0x118/0x1d0
> <6><81230000>
> <6>
> <6>2f890000
> <6>[ae70db80] [8007b608] hrtimer_interrupt+0xd8/0x270
> <6>40befff4
> <6>
> <6>7c421378
> <6>[ae70dbd0] [8000983c] __timer_interrupt+0xac/0x1b0
> <6>
> <6>
> <6>[ae70dbf0] [80009b70] timer_interrupt+0xb0/0xe0
> <6>[ae70dc10] [8000f450] ret_from_except+0x0/0x18
> <6>--- interrupt: 901 at _raw_spin_lock_bh+0x3c/0x70
> <6>    LR = tipc_nametbl_withdraw+0x4c/0x140 [tipc]
> <6>[ae70dcd0] [a85d99a0] 0xa85d99a0 (unreliable)
> <6>[ae70dd00] [c13f3c34] tipc_nl_node_dump_link+0x1904/0x45d0 [tipc]
> <6>[ae70dd30] [c13f4848] tipc_nl_node_dump_link+0x2518/0x45d0 [tipc]
> <6>[ae70dd70] [804f29e0] sock_release+0x30/0xf0
> <6>[ae70dd80] [804f2ab4] sock_close+0x14/0x30
> <6>[ae70dd90] [80105844] __fput+0x94/0x200
> <6>[ae70ddb0] [8003dca4] task_work_run+0xd4/0x100
> <6>[ae70ddd0] [80023620] do_exit+0x280/0x980
> <6>[ae70de10] [80024c48] do_group_exit+0x48/0xb0
> <6>[ae70de30] [80030344] get_signal+0x244/0x4f0
> <6>[ae70de80] [80007734] do_signal+0x34/0x1c0
> <6>[ae70df30] [800079a8] do_notify_resume+0x68/0x80
> <6>[ae70df40] [8000fa1c] do_user_signal+0x74/0xc4
> <6>--- interrupt: c00 at 0xfe490c4
> <6>    LR = 0xfe490a0
>
>
>
> On Wed, Nov 23, 2016 at 9:16 PM, Parthasarathy Bhuvaragan
> <parthasarathy.bhuvara...@ericsson.com
> <mailto:parthasarathy.bhuvara...@ericsson.com>> wrote:
>
>     Hi John,
>
>     Ok. Can you test with the 2 patches I posted regarding the nametbl_lock?
>
>     /Partha
>
>     On 11/21/2016 11:32 PM, John Thompson wrote:
>
>         Hi Partha,
>
>         My test has 4 nodes, 2 of which are alternately rebooting.  When the
>         rebooted node rejoins a few minutes pass and then the other node is
>         rebooted.
>         I am not printing out link stats and believe that the the other
>         code is
>         not doing so either, when nodes leave or rejoin.
>
>         JT
>
>
>         On Tue, Nov 22, 2016 at 2:22 AM, Parthasarathy Bhuvaragan
>         <parthasarathy.bhuvara...@ericsson.com
>         <mailto:parthasarathy.bhuvara...@ericsson.com>
>         <mailto:parthasarathy.bhuvara...@ericsson.com
>         <mailto:parthasarathy.bhuvara...@ericsson.com>>> wrote:
>
>             Hi,
>
>             There is an other branch where softlockup for nametbl_lock
>         occurs.
>
>             tipc_named_rcv() Grabs nametbl_lock
>               tipc_update_nametbl() (publish/withdraw)
>                 tipc_node_subscribe()/unsubscribe()
>                   tipc_node_write_unlock()
>                      << lockup occurs if it needs to process NODE
>         UP/DOWN LINK
>             UP/DOWN, as it grabs nametbl_lock again >>
>
>             /Partha
>
>
>             On 11/21/2016 01:04 PM, Parthasarathy Bhuvaragan wrote:
>
>                 Hi,
>
>                 tipc_nametbl_withdraw() triggers the softlockup as it
>         tries to grab
>                 nametbl_lock twice if the node triggered a
>         TIPC_NOTIFY_LINK_DOWN
>                 event
>                 while its is running. The erroneous call chain is:
>
>                   tipc_nametbl_withdraw() Grab nametbl_lock
>                     tipc_named_process_backlog()
>                       tipc_update_nametbl()
>                         if (dtype == WITHDRAWAL) tipc_node_unsubscribe()
>                           tipc_node_write_unlock()
>                             if (flags & TIPC_NOTIFY_LINK_DOWN)
>                 tipc_nametbl_withdraw()
>                                spin_lock_bh(&tn->nametbl_lock);  << Soft
>         Lockup >>
>
>                 Three callers which can cause this under module exit:
>
>                 Case1:
>                   tipc_exit_net()
>                     tipc_nametbl_withdraw() Grab nametbl_lock
>
>                 Case2:
>                   tipc_server_stop()
>                     tipc_conn_kref_release
>                       tipc_sock_release
>                         sock_release()
>                           tipc_release()
>                             tipc_sk_withdraw()
>                               tipc_nametbl_withdraw()
>
>                 Case3:
>                   tipc_server_stop()
>                     tipc_conn_kref_release()
>                       kernel_bind()
>                         tipc_bind()
>                           tipc_sk_withdraw()
>                             tipc_nametbl_withdraw()
>
>                 I will work on a solution for this.
>
>                 What kind of test were you performing when this occurred
>                 (linkup/down)?
>                 Do you read link statistics periodically in your tests?
>
>                 /Partha
>
>                 On 11/21/2016 05:30 AM, John Thompson wrote:
>
>                     Hi Partha,
>
>                     I was doing some some more testing today and have still
>                     observed the
>                     problem (contrary to what I had emailed earlier).
>
>                     Here is the kernel dump.
>
>                     <0>NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s!
>                     [Pluggable
>                     Serve:2221]
>                     <6>Modules linked in: tipc jitterentropy_rng
>         echainiv drbg
>                     platform_driver(O)
>                     <6>CPU: 0 PID: 2221 Comm: Pluggable Serve Tainted:
>         P           O
>                     <6>task: ae54ced0 ti: aec42000 task.ti: aec42000
>                     <6>NIP: 8069257c LR: c13ebf50 CTR: 80692540
>                     <6>REGS: aec43ad0 TRAP: 0901   Tainted: P           O
>                     <6>MSR: 00029002 <CE,EE,ME>  CR: 48002444  XER: 00000000
>                     <6>
>                     <6>GPR00: c13ea408 aec43b80 ae54ced0 a624690c 00000000
>                     a6271d84 a39a60cc
>                     fffffffd
>                     <6>GPR08: aeefbbc8 00000001 00000001 00000004 80692540
>                     <6>NIP [8069257c] _raw_spin_lock_bh+0x3c/0x70
>                     <6>LR [c13ebf50] tipc_nametbl_unsubscribe+0x50/0x120
>         [tipc]
>                     <6>Call Trace:
>                     <6>[aec43b80] [800fa258] check_object+0xc8/0x270
>         (unreliable)
>                     <6>[aec43ba0] [c13ea408]
>         tipc_named_reinit+0xf8/0x820 [tipc]
>                     <6>[aec43bb0] [c13ea6c0]
>         tipc_named_reinit+0x3b0/0x820 [tipc]
>                     <6>[aec43bd0] [c13f7bbc]
>         tipc_nl_publ_dump+0x50c/0xed0 [tipc]
>                     <6>[aec43c00] [c13f865c]
>         tipc_conn_sendmsg+0xdc/0x170 [tipc]
>                     <6>[aec43c30] [c13eacbc]
>                     tipc_subscrp_report_overlap+0xbc/0xd0 [tipc]
>                     <6>[aec43c70] [c13eb27c]
>         tipc_topsrv_stop+0x45c/0x4f0 [tipc]
>                     <6>[aec43ca0] [c13eb7a8]
>         tipc_nametbl_remove_publ+0x58/0x110
>                     [tipc]
>                     <6>[aec43cd0] [c13ebc68]
>         tipc_nametbl_withdraw+0x68/0x140 [tipc]
>                     <6>[aec43d00] [c13f3c34]
>                     tipc_nl_node_dump_link+0x1904/0x45d0 [tipc]
>                     <6>[aec43d30] [c13f4848]
>                     tipc_nl_node_dump_link+0x2518/0x45d0 [tipc]
>
>                 TIPC_CMD_SHOW_LINK_STATS or TIPC_NL_LINK_GET
>
>                     <6>[aec43d70] [804f29e0] sock_release+0x30/0xf0
>                     <6>[aec43d80] [804f2ab4] sock_close+0x14/0x30
>                     <6>[aec43d90] [80105844] __fput+0x94/0x200
>                     <6>[aec43db0] [8003dca4] task_work_run+0xd4/0x100
>                     <6>[aec43dd0] [80023620] do_exit+0x280/0x980
>                     <6>[aec43e10] [80024c48] do_group_exit+0x48/0xb0
>                     <6>[aec43e30] [80030344] get_signal+0x244/0x4f0
>                     <6>[aec43e80] [80007734] do_signal+0x34/0x1c0
>                     <6>[aec43f30] [800079a8] do_notify_resume+0x68/0x80
>                     <6>[aec43f40] [8000fa1c] do_user_signal+0x74/0xc4
>                     <6>--- interrupt: c00 at 0xf4f3d08
>                     <6>    LR = 0xf4f3ce8
>                     <6>Instruction dump:
>                     <6>912a0008 39400001 7d201828 2c090000 40820010 7d40192d
>                     40a2fff0 7c2004ac
>                     <6>2f890000 4dbe0020 7c210b78 81230000 <2f890000>
>         40befff4
>                     7c421378
>                     7d201828
>                     <0>Kernel panic - not syncing: softlockup: hung tasks
>                     <6>CPU: 0 PID: 2221 Comm: Pluggable Serve Tainted: P
>                        O L
>                     <6>Call Trace:
>                     <6>[aec43930] [80694e20] dump_stack+0x84/0xb0
>         (unreliable)
>                     <6>[aec43940] [80692ca8] panic+0xd8/0x214
>                     <6>[aec439a0] [800a0258] watchdog_timer_fn+0x2d8/0x2e0
>                     <6>[aec439f0] [8007ae58]
>         __hrtimer_run_queues+0x118/0x1d0
>                     <6>[aec43a30] [8007b608] hrtimer_interrupt+0xd8/0x270
>                     <6>[aec43a80] [8000983c] __timer_interrupt+0xac/0x1b0
>                     <6>[aec43aa0] [80009b70] timer_interrupt+0xb0/0xe0
>                     <6>[aec43ac0] [8000f450] ret_from_except+0x0/0x18
>                     <6>--- interrupt: 901 at _raw_spin_lock_bh+0x3c/0x70
>                     <6>    LR = tipc_nametbl_unsubscribe+0x50/0x120 [tipc]
>                     <6>[aec43b80] [800fa258] check_object+0xc8/0x270
>         (unreliable)
>                     <6>[aec43ba0] [c13ea408]
>         tipc_named_reinit+0xf8/0x820 [tipc]
>                     <6>[aec43bb0] [c13ea6c0]
>         tipc_named_reinit+0x3b0/0x820 [tipc]
>                     <6>[aec43bd0] [c13f7bbc]
>         tipc_nl_publ_dump+0x50c/0xed0 [tipc]
>                     <6>[aec43c00] [c13f865c]
>         tipc_conn_sendmsg+0xdc/0x170 [tipc]
>                     <6>[aec43c30] [c13eacbc]
>                     tipc_subscrp_report_overlap+0xbc/0xd0 [tipc]
>                     <6>[aec43c70] [c13eb27c]
>         tipc_topsrv_stop+0x45c/0x4f0 [tipc]
>                     <6>[aec43ca0] [c13eb7a8]
>         tipc_nametbl_remove_publ+0x58/0x110
>                     [tipc]
>                     <6>[aec43cd0] [c13ebc68]
>         tipc_nametbl_withdraw+0x68/0x140 [tipc]
>                     <6>[aec43d00] [c13f3c34]
>                     tipc_nl_node_dump_link+0x1904/0x45d0 [tipc]
>                     <6>[aec43d30] [c13f4848]
>                     tipc_nl_node_dump_link+0x2518/0x45d0 [tipc]
>                     <6>[aec43d70] [804f29e0] sock_release+0x30/0xf0
>                     <6>[aec43d80] [804f2ab4] sock_close+0x14/0x30
>                     <6>[aec43d90] [80105844] __fput+0x94/0x200
>                     <6>[aec43db0] [8003dca4] task_work_run+0xd4/0x100
>                     <6>[aec43dd0] [80023620] do_exit+0x280/0x980
>                     <6>[aec43e10] [80024c48] do_group_exit+0x48/0xb0
>                     <6>[aec43e30] [80030344] get_signal+0x244/0x4f0
>                     <6>[aec43e80] [80007734] do_signal+0x34/0x1c0
>                     <6>[aec43f30] [800079a8] do_notify_resume+0x68/0x80
>                     <6>[aec43f40] [8000fa1c] do_user_signal+0x74/0xc4
>                     <6>--- interrupt: c00 at 0xf4f3d08
>                     <6>    LR = 0xf4f3ce8
>
>
>                     On Mon, Nov 21, 2016 at 9:59 AM, John Thompson
>                     <thompa....@gmail.com <mailto:thompa....@gmail.com>
>         <mailto:thompa....@gmail.com <mailto:thompa....@gmail.com>>
>                     <mailto:thompa....@gmail.com
>         <mailto:thompa....@gmail.com> <mailto:thompa....@gmail.com
>         <mailto:thompa....@gmail.com>>>>
>                     wrote:
>
>                         Hi Partha,
>
>                         In my testing over the weekend the patch
>         performed well
>                     - I didn't
>                         see any kernel dumps due to this issue.
>
>                         Thanks for the quick response.
>                         JT
>
>
>                         On Fri, Nov 18, 2016 at 10:34 AM, John Thompson
>                         <thompa....@gmail.com
>         <mailto:thompa....@gmail.com> <mailto:thompa....@gmail.com
>         <mailto:thompa....@gmail.com>>
>                     <mailto:thompa....@gmail.com
>         <mailto:thompa....@gmail.com> <mailto:thompa....@gmail.com
>         <mailto:thompa....@gmail.com>>>>
>                     wrote:
>
>                             Hi,
>
>                             I will be able to have some test results by the
>                     start of next
>                             week on the first patch.
>
>                             Regards,
>                             JT
>
>
>                             On Thu, Nov 17, 2016 at 11:27 PM, Ying Xue
>                             <ying....@windriver.com
>         <mailto:ying....@windriver.com>
>                     <mailto:ying....@windriver.com
>         <mailto:ying....@windriver.com>>
>                     <mailto:ying....@windriver.com
>         <mailto:ying....@windriver.com>
>                     <mailto:ying....@windriver.com
>         <mailto:ying....@windriver.com>>>> wrote:
>
>                                 On 11/17/2016 07:04 AM, John Thompson wrote:
>
>                                     Hi Partha / Ying,
>
>                                     I will try out the patch and let you
>         know
>                     how it goes.
>                                     I also note about providing the
>         other CPU
>                     core dumps -
>                                     in one of my cases I
>                                     didn't have them but in others I did but
>                                     they were interleaved and so were
>         difficult
>                     to interpret.
>
>
>                                 Thanks, it's unnecessary for us to
>         collect more
>                     logs as its
>                                 soft lockup scenario should be just what
>         Partha
>                     described.
>
>                                 Regards,
>                                 Ying
>
>
>
>                                     Thanks for getting a patch together
>         so quickly.
>
>                                     JT
>
>                                     On Wed, Nov 16, 2016 at 10:23 PM,
>                     Parthasarathy Bhuvaragan <
>
>         parthasarathy.bhuvara...@ericsson.com
>         <mailto:parthasarathy.bhuvara...@ericsson.com>
>                     <mailto:parthasarathy.bhuvara...@ericsson.com
>         <mailto:parthasarathy.bhuvara...@ericsson.com>>
>
>                     <mailto:parthasarathy.bhuvara...@ericsson.com
>         <mailto:parthasarathy.bhuvara...@ericsson.com>
>
>                     <mailto:parthasarathy.bhuvara...@ericsson.com
>         <mailto:parthasarathy.bhuvara...@ericsson.com>>>> wrote:
>
>                                         Hi Ying / John,
>
>                                         The soft lock is the call chain of
>                                         tipc_nametbl_withdraw(), when it
>                                         performs the
>         tipc_conn_kref_release() as
>                     it tries to
>                                         grab nametbl_lock
>                                         again while holding it already.
>
>                                             tipc_nametbl_withdraw
>
>         spin_lock_bh(&tn->nametbl_lock);
>                                               tipc_nametbl_remove_publ
>                                                  spin_lock_bh(&seq->lock);
>                                                  tipc_nameseq_remove_publ
>
>          tipc_subscrp_report_overlap
>                                                      tipc_subscrp_send_event
>                                                         tipc_conn_sendmsg
>
>                                         << Here, the (test_bit(CF_CONNECTED,
>                     &con->flags))
>                                         Fails, leading to the
>                                         else case where do do a
>         conn_put() and
>                     that triggers
>                                         the cleanup as
>                                         refcount reached 0. Leading the call
>                     chain below : >>
>                                         tipc_conn_kref_release
>                                            tipc_sock_release
>                                              tipc_conn_release
>                                                 tipc_subscrb_delete
>                                                    tipc_subscrp_delete
>
>         tipc_nametbl_unsubscribe
>
>                      spin_lock_bh(&tn->nametbl_lock);
>                                         << !! Soft Lockup >>
>
>                                         One cause is that
>         tipc_exit_net() calls
>                     first calls
>                                         tipc_topsrv_stop() and
>                                         then tipc_nametbl_withdraw() in
>         scope of
>                                         tipc_net_stop().
>
>                                         The above chain will only occur in a
>                     narrow window
>                                         for a given connection:
>                                         CPU#1:
>                                         tipc_nametbl_withdraw() manages
>         to perform
>                                         tipc_conn_lookup() and steps
>                                         the refcount to 2, while in
>         CPU#2 the
>                     following occurs:
>                                         CPU#2:
>                                         tipc_server_stop() calls
>                     tipc_close_conn(con). This
>                                         performs a conn_put()
>                                         decrementing refcount to 1.
>                                         Now, CPU#1 continues and detects
>         that
>                     the connection
>                                         is not CF_CONNECTED
>                                         and does a conn_put(),
>         triggering the
>                     release callback.
>
>                                         Before commit 333f796235a527,
>         the above
>                     wont happen.
>
>                                         /Partha
>
>
>                                         On 11/15/2016 04:11 PM, Xue,
>         Ying wrote:
>
>                                             Hi John,
>
>                                             Regarding the stack trace you
>                     provided below, I
>                                             get the two potential
>                                             call chains:
>
>                                             tipc_nametbl_withdraw
>
>         spin_lock_bh(&tn->nametbl_lock);
>                                               tipc_nametbl_remove_publ
>                                                  spin_lock_bh(&seq->lock);
>                                                  tipc_nameseq_remove_publ
>
>          tipc_subscrp_report_overlap
>                                                      tipc_subscrp_send_event
>                                                         tipc_conn_sendmsg
>
>                      spin_lock_bh(&con->outqueue_lock);
>
>          list_add_tail(&e->list,
>                                             &con->outqueue);
>
>
>                                             tipc_topsrv_stop
>                                               tipc_server_stop
>                                                 tipc_close_conn
>                                                   kernel_sock_shutdown
>                                                     tipc_subscrb_delete
>
>                     spin_lock_bh(&subscriber->lock);
>
>         tipc_nametbl_unsubscribe(sub);
>
>                      spin_lock_bh(&tn->nametbl_lock);
>
>                                             Although I suspect this is a
>         revert
>                     lock issue
>                                             leading to the soft
>                                             lockup, I am still unable to
>                     understand which
>                                             lock together with
>                                             nametbl_lock is taken
>         reversely on
>                     the two
>                                             different paths above.
>                                             However, you just gave us
>         the log
>                     printed on
>                                             CPU#2, but the logs
>                                             outputted by other cores are
>         also
>                     important.  So
>                                             if possible, please share
>                                             them with us.
>
>                                             By the way, I agree with
>         you, and it
>                     seems that
>                                             commit 333f796235a527 is
>                                             related to the soft lockup.
>
>                                             Regards,
>                                             Ying
>
>                                             -----Original Message-----
>                                             From: John Thompson
>                     [mailto:thompa....@gmail.com
>         <mailto:thompa....@gmail.com> <mailto:thompa....@gmail.com
>         <mailto:thompa....@gmail.com>>
>                                             <mailto:thompa....@gmail.com
>         <mailto:thompa....@gmail.com>
>                     <mailto:thompa....@gmail.com
>         <mailto:thompa....@gmail.com>>>]
>                                             Sent: Tuesday, November 15,
>         2016 8:01 AM
>                                             To:
>                     tipc-discussion@lists.sourceforge.net
>         <mailto:tipc-discussion@lists.sourceforge.net>
>                     <mailto:tipc-discussion@lists.sourceforge.net
>         <mailto:tipc-discussion@lists.sourceforge.net>>
>
>                     <mailto:tipc-discussion@lists.sourceforge.net
>         <mailto:tipc-discussion@lists.sourceforge.net>
>
>                     <mailto:tipc-discussion@lists.sourceforge.net
>         <mailto:tipc-discussion@lists.sourceforge.net>>>
>                                             Subject: [tipc-discussion] v4.7:
>                     soft lockup
>                                             when releasing a socket
>
>                                             Hi,
>
>                                             I am seeing an occasional kernel
>                     soft lockup.  I
>                                             have TIPC v4.7 and the
>                                             kernel dump occurs when the
>         system
>                     is going down
>                                             for a reboot.
>
>                                             The kernel dump is:
>
>                                             <0>NMI watchdog: BUG: soft
>         lockup -
>                     CPU#2 stuck
>                                             for 23s! [exfx:1474]
>                                             <6>Modules linked in: tipc
>                     jitterentropy_rng
>                                             echainiv drbg
>                                             platform_driver(O) ipifwd(PO)
>                                             ...
>                                             <6>
>                                             <6>GPR00: c15333e8 a4e0fb80
>         a4ee3600
>                     a51748ac
>                                             00000000 ae475024 a537feec
>                                             fffffffd
>                                             <6>GPR08: a2197408 00000001
>         00000001
>                     00000004
>                                             80691c00 <6>NIP [80691c40]
>                                             _raw_spin_lock_bh+0x40/0x70
>         <6>LR
>                     [c1534f30]
>
>         tipc_nametbl_unsubscribe+0x50/0x120
>                                             [tipc] <6>Call Trace:
>                                             <6>[a4e0fba0] [c15333e8]
>                                             tipc_named_reinit+0xf8/0x820
>         [tipc]
>                                             <6>[a4e0fbb0] [c15336a0]
>
>         tipc_named_reinit+0x3b0/0x820 [tipc]
>                     <6>[a4e0fbd0]
>                                             [c1540bac]
>                     tipc_nl_publ_dump+0x50c/0xed0 [tipc]
>                                             <6>[a4e0fc00] [c154164c]
>                                             tipc_conn_sendmsg+0xdc/0x170
>         [tipc]
>                                             <6>[a4e0fc30] [c1533c9c]
>
>                     tipc_subscrp_report_overlap+0xbc/0xd0 [tipc]
>                                             <6>[a4e0fc70] [c153425c]
>                                             tipc_topsrv_stop+0x45c/0x4f0
>         [tipc]
>                                             <6>[a4e0fca0] [c1534788]
>
>         tipc_nametbl_remove_publ+0x58/0x110
>                     [tipc]
>                                             <6>[a4e0fcd0] [c1534c48]
>
>         tipc_nametbl_withdraw+0x68/0x140 [tipc]
>                                             <6>[a4e0fd00] [c153cc24]
>
>         tipc_nl_node_dump_link+0x1904/0x45d0
>                     [tipc]
>                                             <6>[a4e0fd30] [c153d838]
>
>         tipc_nl_node_dump_link+0x2518/0x45d0
>                     [tipc]
>                                             <6>[a4e0fd70] [804f2870]
>                                             sock_release+0x30/0xf0
>         <6>[a4e0fd80]
>                     [804f2944]
>                                             sock_close+0x14/0x30
>                                             <6>[a4e0fd90] [80105844]
>                     __fput+0x94/0x200
>                                             <6>[a4e0fdb0] [8003dca4]
>                                             task_work_run+0xd4/0x100
>         <6>[a4e0fdd0]
>                                             [80023620] do_exit+0x280/0x980
>                                             <6>[a4e0fe10] [80024c48]
>                     do_group_exit+0x48/0xb0
>                                             <6>[a4e0fe30] [80030344]
>                                             get_signal+0x244/0x4f0
>         <6>[a4e0fe80]
>                     [80007734]
>                                             do_signal+0x34/0x1c0
>                                             <6>[a4e0ff30] [800079a8]
>                                             do_notify_resume+0x68/0x80
>         <6>[a4e0ff40]
>                                             [8000fa1c]
>         do_user_signal+0x74/0xc4
>
>
>                                             From the stack dump it looks
>         like
>                                             tipc_named_reinit is trying to
>
>
>                                             acquire nametbl_lock.
>
>                                             From looking at the call
>         chain I can
>                     see that
>                                             tipc_conn_sendmsg can
>
>
>                                             send up calling conn_put
>
>                                             which will go on and call the
>                     tipc_named_reinit
>                                             via tipc_sock_release.
>
>                                             As tipc_nametbl_withdraw
>         (from the
>                     stack dump)
>                                             has already acquired the
>                                             nametbl_lock, tipc_named_reinit
>
>                                             cannot get it and so the
>         process hangs.
>
>
>                                             The call to
>         tipc_sock_release (added
>                     in Commit
>                                             333f796235a527
>
>
>         <http://git.atlnz.lc/cgit/cgit.cgi/upstream_imports/linux-
>         <http://git.atlnz.lc/cgit/cgit.cgi/upstream_imports/linux->
>
>         <http://git.atlnz.lc/cgit/cgit.cgi/upstream_imports/linux-
>         <http://git.atlnz.lc/cgit/cgit.cgi/upstream_imports/linux->>
>
>
>         <http://git.atlnz.lc/cgit/cgit.cgi/upstream_imports/linux-
>         <http://git.atlnz.lc/cgit/cgit.cgi/upstream_imports/linux->
>
>         <http://git.atlnz.lc/cgit/cgit.cgi/upstream_imports/linux-
>         <http://git.atlnz.lc/cgit/cgit.cgi/upstream_imports/linux->>>
>
>
>         stable.git/commit/?id=333f796235a52727db7e0a13888045f3aa3d5335>)
>                                             seems to have changed the
>         behaviour
>
>                                             such that it tries to do a
>         lot more when
>                                             shutting the connection down.
>
>
>                                             If there is other
>         information I can
>                     provide
>                                             please let me know.
>
>                                             Regards,
>
>                                             John
>
>
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