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:[email protected]]
Sent: Tuesday, November 15, 2016 8:01 AM
To: [email protected]
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] [800077
34] 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-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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