Date: Fri, 11 Nov 2016 13:24:02 +0200 From: Andriy Gapon <avg@FreeBSD.org> To: Henri Hennebert <hlh@restart.be>, freebsd-stable@FreeBSD.org Cc: Konstantin Belousov <kib@FreeBSD.org> Subject: Re: Freebsd 11.0 RELEASE - ZFS deadlock Message-ID: <d25c8035-b710-5de9-ebe3-7990b2d0e3b1@FreeBSD.org> In-Reply-To: <1cb09c54-5f0e-2259-a41a-fefe76b4fe8b@restart.be> References: <0c223160-b76f-c635-bb15-4a068ba7efe7@restart.be> <aaf2df40-b0df-2141-9ed8-5b947d8d5a33@FreeBSD.org> <43c9d4d4-1995-5626-d70a-f92a5b456629@FreeBSD.org> <a14d508d-351f-71f4-c7cc-ac73dbcde357@restart.be> <9d1f9a76-5a8d-6eca-9a50-907d55099847@FreeBSD.org> <6bc95dce-31e1-3013-bfe3-7c2dd80f9d1e@restart.be> <e4878992-a362-3f12-e743-8efa1347cabf@FreeBSD.org> <23a66749-f138-1f1a-afae-c775f906ff37@restart.be> <8e7547ef-87f7-7fab-6f45-221e8cea1989@FreeBSD.org> <6d991cea-b420-531e-12cc-001e4aeed66b@restart.be> <67f2e8bd-bff0-f808-7557-7dabe5cad78c@FreeBSD.org> <1cb09c54-5f0e-2259-a41a-fefe76b4fe8b@restart.be>
next in thread | previous in thread | raw e-mail | index | archive | help
On 10/11/2016 21:41, Henri Hennebert wrote:
> On 11/10/2016 19:40, Andriy Gapon wrote:
>> On 10/11/2016 19:55, Henri Hennebert wrote:
>>>
>>>
>>> On 11/10/2016 18:33, Andriy Gapon wrote:
>>>> On 10/11/2016 18:12, Henri Hennebert wrote:
>>>>> On 11/10/2016 16:54, Andriy Gapon wrote:
>>>>>> On 10/11/2016 17:20, Henri Hennebert wrote:
>>>>>>> On 11/10/2016 15:00, Andriy Gapon wrote:
>>>>>>>> Interesting. I can not spot any suspicious thread that would hold the
>>>>>>>> vnode
>>>>>>>> lock. Could you please run kgdb (just like that, no arguments), then
>>>>>>>> execute
>>>>>>>> 'bt' command and then select a frame when _vn_lock is called with 'fr N'
>>>>>>>> command. Then please 'print *vp' and share the result.
>>>>>>>>
>>>>>>> I Think I miss something in your request:
>>>>>>
>>>>>> Oh, sorry! The very first step should be 'tid 101112' to switch to the
>>>>>> correct
>>>>>> context.
>>>>>>
>>>>>
>>>>> (kgdb) fr 7
>>>>> #7 0xffffffff8063c5b3 in _vn_lock (vp=<value optimized out>, flags=2121728,
>>>>
>>>> "value optimized out" - not good
>>>>
>>>>> file=<value optimized out>,
>>>>> line=<value optimized out>) at vnode_if.h:859
>>>>> 859 vnode_if.h: No such file or directory.
>>>>> in vnode_if.h
>>>>> (kgdb) print *vp
>>>>
>>>> I am not sure if this output is valid, because of the message above.
>>>> Could you please try to navigate to nearby frames and see if vp itself has a
>>>> valid value there. If you can find such a frame please do *vp there.
>>>>
>>>
>>> Does this seems better?
>>
>> Yes!
>>
>>> (kgdb) fr 8
>>> #8 0xffffffff8062a5f7 in vget (vp=0xfffff80049c2c000, flags=2121728,
>>> td=0xfffff80009ba0500) at /usr/src/sys/kern/vfs_subr.c:2523
>>> 2523 if ((error = vn_lock(vp, flags)) != 0) {
>>> (kgdb) print *vp
>>> $1 = {v_tag = 0xffffffff813be535 "zfs", v_op = 0xffffffff813d0f70, v_data =
>>> 0xfffff80049c1f420, v_mount = 0xfffff800093aa660,
>>> v_nmntvnodes = {tqe_next = 0xfffff80049c2c938, tqe_prev = 0xfffff80049c2bb30},
>>> v_un = {vu_mount = 0x0, vu_socket = 0x0,
>>> vu_cdev = 0x0, vu_fifoinfo = 0x0}, v_hashlist = {le_next = 0x0, le_prev =
>>> 0x0}, v_cache_src = {lh_first = 0x0}, v_cache_dst = {
>>> tqh_first = 0xfffff800bfc8e3f0, tqh_last = 0xfffff800bfc8e410}, v_cache_dd =
>>> 0x0, v_lock = {lock_object = {
>>> lo_name = 0xffffffff813be535 "zfs", lo_flags = 117112832, lo_data = 0,
>>> lo_witness = 0x0}, lk_lock = 23, lk_exslpfail = 0,
>>> lk_timo = 51, lk_pri = 96}, v_interlock = {lock_object = {lo_name =
>>> 0xffffffff8099e9e0 "vnode interlock", lo_flags = 16973824,
>>> lo_data = 0, lo_witness = 0x0}, mtx_lock = 4}, v_vnlock =
>>> 0xfffff80049c2c068, v_actfreelist = {
>>> tqe_next = 0xfffff80049c2c938, tqe_prev = 0xfffff80049ae9bd0}, v_bufobj =
>>> {bo_lock = {lock_object = {
>>> lo_name = 0xffffffff8099e9f0 "bufobj interlock", lo_flags = 86179840,
>>> lo_data = 0, lo_witness = 0x0}, rw_lock = 1},
>>> bo_ops = 0xffffffff80c4bf70, bo_object = 0xfffff800b62e9c60, bo_synclist =
>>> {le_next = 0x0, le_prev = 0x0},
>>> bo_private = 0xfffff80049c2c000, __bo_vnode = 0xfffff80049c2c000, bo_clean =
>>> {bv_hd = {tqh_first = 0x0,
>>> tqh_last = 0xfffff80049c2c120}, bv_root = {pt_root = 0}, bv_cnt = 0},
>>> bo_dirty = {bv_hd = {tqh_first = 0x0,
>>> tqh_last = 0xfffff80049c2c140}, bv_root = {pt_root = 0}, bv_cnt = 0},
>>> bo_numoutput = 0, bo_flag = 0, bo_bsize = 131072},
>>> v_pollinfo = 0x0, v_label = 0x0, v_lockf = 0x0, v_rl = {rl_waiters =
>>> {tqh_first = 0x0, tqh_last = 0xfffff80049c2c188},
>>> rl_currdep = 0x0}, v_cstart = 0, v_lasta = 0, v_lastw = 0, v_clen = 0,
>>> v_holdcnt = 9, v_usecount = 6, v_iflag = 512,
>>> v_vflag = 32, v_writecount = 0, v_hash = 4833984, v_type = VREG}
>>> (kgdb)
>>
>> flags=2121728 = 0x206000 = LK_SHARED | LK_VNHELD | LK_NODDLKTREAT
>> lk_lock = 23 = 0x17 = LK_ONE_SHARER | LK_EXCLUSIVE_WAITERS | LK_SHARED_WAITERS |
>> LK_SHARE
>>
>> So, here's what we have here: this thread tries to get a shared lock on the
>> vnode, the vnode is already locked in shared mode, but there is an exclusive
>> waiter (or, perhaps, multiple waiters). So, this thread can not get the lock
>> because of the exclusive waiter. And I do not see an easy way to identify that
>> waiter.
>>
>> In the procstat output that you provided earlier there was no other thread in
>> vn_lock. Hmm, I see this:
>> procstat: sysctl: kern.proc.kstack: 14789: Device busy
>> procstat: sysctl: kern.proc.kstack: 82034: Device busy
>>
>> Could you please check what those two processes are (if they are still running)?
>> Perhaps try procstat for each of the pids several times.
>>
At this stage I would try to get a system crash dump for post-mortem analysis.
There are a few way to do that. You can enter ddb and then run 'dump' and
'reset' commands. Or you can just do `sysctl debug.kdb.panic=1`.
In either case, please double-check that your system has a dump device configured.
> This 2 processes are the 2 instances of the innd daemon (news server) which
> seems in accordance with the directory /usr/local/news/bin.
>
> [root@avoriaz ~]# procstat 14789
> PID PPID PGID SID TSID THR LOGIN WCHAN EMUL COMM
> 14789 29165 29165 29165 0 1 root zfs FreeBSD ELF64 innd
> [root@avoriaz ~]# procstat 82034
> PID PPID PGID SID TSID THR LOGIN WCHAN EMUL COMM
> 82034 29165 29165 29165 0 1 root zfs FreeBSD ELF64 innd
> [root@avoriaz ~]# procstat -f 14789
> procstat: kinfo_getfile(): Device busy
> PID COMM FD T V FLAGS REF OFFSET PRO NAME
> [root@avoriaz ~]# procstat -f 14789
> procstat: kinfo_getfile(): Device busy
> PID COMM FD T V FLAGS REF OFFSET PRO NAME
> [root@avoriaz ~]# procstat -f 14789
> procstat: kinfo_getfile(): Device busy
> PID COMM FD T V FLAGS REF OFFSET PRO NAME
> [root@avoriaz ~]# procstat -f 14789
> procstat: kinfo_getfile(): Device busy
> PID COMM FD T V FLAGS REF OFFSET PRO NAME
> [root@avoriaz ~]# procstat -kk 14789
> PID TID COMM TDNAME KSTACK
> procstat: sysctl: kern.proc.kstack: 14789: Device busy
> [root@avoriaz ~]# procstat -kk 14789
> PID TID COMM TDNAME KSTACK
> procstat: sysctl: kern.proc.kstack: 14789: Device busy
> [root@avoriaz ~]# procstat -kk 14789
> PID TID COMM TDNAME KSTACK
> procstat: sysctl: kern.proc.kstack: 14789: Device busy
> [root@avoriaz ~]# procstat -kk 14789
> PID TID COMM TDNAME KSTACK
> procstat: sysctl: kern.proc.kstack: 14789: Device busy
> [root@avoriaz ~]#
>
> Same result for 82034.
>
> By the way the news server seems OK:
>
> [root@avoriaz ~]# ctlinnd mode
> Server running
> Allowing remote connections
> Parameters c 14 i 50 (0) l 5000000 o 1010 t 300 H 2 T 60 X 0 normal specified
> Not reserved
> Readers follow enabled
> Perl filtering enabled
> [root@avoriaz ~]#
>
> I can access the news server with thunderbird.
>
> I can restart the news server if you ask
>
> Henri
--
Andriy Gapon
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?d25c8035-b710-5de9-ebe3-7990b2d0e3b1>