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Date:      Wed, 23 Sep 2015 20:32:36 +0200
From:      Julien Charbon <jch@freebsd.org>
To:        Palle Girgensohn <girgen@pingpong.net>
Cc:        Palle Girgensohn <girgen@gmail.com>, George Neville-Neil <gnn@FreeBSD.org>, freebsd-net@freebsd.org
Subject:   Re: Kernel panics in tcp_twclose
Message-ID:  <5602F044.5010606@freebsd.org>
In-Reply-To: <0931591A-23EC-40CB-A109-72E9308B1A2D@pingpong.net>
References:  <26B0FF93-8AE3-4514-BDA1-B966230AAB65@FreeBSD.org> <55FC1809.3070903@freebsd.org> <20150918160605.GN67105@kib.kiev.ua> <55FFBE01.6060706@freebsd.org> <3721F099-F45D-4DCD-8AB3-84D1ABC44145@FreeBSD.org> <73856F2B-3E70-483C-9988-C84E798CEB44@FreeBSD.org> <44EBAC98-4761-4E47-8E47-5032430A1C8A@FreeBSD.org> <56019AF8.8000705@freebsd.org> <F9D29C16-502B-43A1-BE2C-D2AD30F0B9EF@FreeBSD.org> <5601CF2D.9030307@freebsd.org> <E09DF89D-AAC5-48FD-8B75-EEAB937A5C32@FreeBSD.org> <5602E90A.9050504@freebsd.org> <0931591A-23EC-40CB-A109-72E9308B1A2D@pingpong.net>

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 Hi,

On 23/09/15 20:26, Palle Girgensohn wrote:
>> 23 sep. 2015 kl. 20:01 skrev Julien Charbon <jch@freebsd.org>:
>> On 23/09/15 16:36, Palle Girgensohn wrote:
>>>> 22 sep 2015 kl. 23:59 skrev Julien Charbon <jch@freebsd.org>: On
>>>> 22/09/15 22:58, Palle Girgensohn wrote:
>>>>>> 22 sep 2015 kl. 20:16 skrev Julien Charbon <jch@freebsd.org>:=20
>>>>>> On 22/09/15 18:49, Palle Girgensohn wrote:
>>>>>>>> 22 sep 2015 kl. 18:46 skrev Palle Girgensohn=20
>>>>>>>> <girgen@FreeBSD.org>:
>>>>>>>>> 21 sep 2015 kl. 15:53 skrev Palle Girgensohn=20
>>>>>>>>> <girgen@FreeBSD.org>:
>>>>>>>>>> 21 sep 2015 kl. 10:21 skrev Julien Charbon=20
>>>>>>>>>> <jch@FreeBSD.org>: On 18/09/15 18:06, Konstantin
>>>>>>>>>> Belousov wrote:
>>>>>>>>>>> On Fri, Sep 18, 2015 at 03:56:25PM +0200, Julien
>>>>>>>>>>> Charbon wrote:
>>>>>>>>>>>> [...]
>>>>>>>>>> - Second, if issue is still in stable/10, compile 10.2=20
>>>>>>>>>> kernel with these options:
>>>>>>>>>>
>>>>>>>>>> options        DDB options        DEADLKRES options=20
>>>>>>>>>> INVARIANTS options        INVARIANT_SUPPORT options
>>>>>>>>>> WITNESS options        WITNESS_SKIPSPIN
>>>>>>>>>>
>>>>>>>>>> To see where the original fault is coming from.
>>>>>>>>> [...]
>>>>>>>>>
>>>>>>>>> I'll try stable/10 now. Would you suggest a "clean"=20
>>>>>>>>> stable/10, or could 287621 and 287780 help?
>>>>>>>>>
>>>>>>>>> I'll add the debugging suggested options right away.
>>>>>>>>>
>>>>>>>>> Palle
>>>>>>>>
>>>>>>>> I have a new core dump from ^/stable/10 with:
>>>>>>>>
>>>>>>>> options        DDB options        DEADLKRES options
>>>>>>>> INVARIANTS options        INVARIANT_SUPPORT options WITNESS
>>>>>>>> options WITNESS_SKIPSPIN
>>>>>>>
>>>>>>> # kgdb kernel /var/crash/vmcore.2 GNU gdb 6.1.1 [FreeBSD]=20
>>>>>>> Copyright 2004 Free Software Foundation, Inc. GDB is free=20
>>>>>>> software, covered by the GNU General Public License, and you
>>>>>>> are welcome to change it and/or distribute copies of it under
>>>>>>> certain conditions. Type "show copying" to see the
>>>>>>> conditions. There is absolutely no warranty for GDB.  Type
>>>>>>> "show warranty" for details. This GDB was configured as
>>>>>>> "amd64-marcel-freebsd"...
>>>>>>>
>>>>>>> Unread portion of the kernel message buffer: panic:
>>>>>>> tcp_detach: INP_TIMEWAIT && INP_DROPPED && tp !=3D NULL cpuid =3D=

>>>>>>> 16 KDB: stack backtrace: db_trace_self_wrapper() at=20
>>>>>>> db_trace_self_wrapper+0x2b/frame 0xfffffe183d9e97e0=20
>>>>>>> kdb_backtrace() at kdb_backtrace+0x39/frame
>>>>>>> 0xfffffe183d9e9890 vpanic() at vpanic+0x126/frame
>>>>>>> 0xfffffe183d9e98d0 kassert_panic() at
>>>>>>> kassert_panic+0x139/frame 0xfffffe183d9e9940
>>>>>>> tcp_usr_detach() at tcp_usr_detach+0xf9/frame
>>>>>>> 0xfffffe183d9e9970 sofree() at sofree+0x1f1/frame
>>>>>>> 0xfffffe183d9e99a0 soclose() at soclose+0x3a0/frame
>>>>>>> 0xfffffe183d9e99f0 _fdrop() at _fdrop+0x29/frame
>>>>>>> 0xfffffe183d9e9a10 closef() at closef+0x1e2/frame
>>>>>>> 0xfffffe183d9e9aa0 closefp() at closefp+0x9d/frame
>>>>>>> 0xfffffe183d9e9ae0 amd64_syscall() at=20
>>>>>>> amd64_syscall+0x25a/frame 0xfffffe183d9e9bf0 Xfast_syscall()
>>>>>>> at Xfast_syscall+0xfb/frame 0xfffffe183d9e9bf0 --- syscall
>>>>>>> (6, FreeBSD ELF64, sys_close), rip =3D 0x801c8d94a, rsp =3D=20
>>>>>>> 0x7ffff91c8668, rbp =3D 0x7ffff91c8680 --- KDB: enter: panic=20
>>>>>>> Uptime: 18h57m59s Dumping 23085 out of 98263=20
>>>>>>> MB:..1%..11%..21%..31%..41%..51%..61%..71%..81%..91%
>>>>>>>
>>>>>>> Reading symbols from /boot/kernel/nullfs.ko.symbols...done.=20
>>>>>>> Loaded symbols for /boot/kernel/nullfs.ko.symbols Reading
>>>>>>> symbols from /boot/kernel/zfs.ko.symbols...done. Loaded
>>>>>>> symbols for /boot/kernel/zfs.ko.symbols Reading symbols from
>>>>>>> /boot/kernel/opensolaris.ko.symbols...done. Loaded symbols
>>>>>>> for /boot/kernel/opensolaris.ko.symbols Reading symbols from
>>>>>>> /boot/kernel/ng_bridge.ko.symbols...done. Loaded symbols for
>>>>>>> /boot/kernel/ng_bridge.ko.symbols Reading symbols from=20
>>>>>>> /boot/kernel/netgraph.ko.symbols...done. Loaded symbols for=20
>>>>>>> /boot/kernel/netgraph.ko.symbols Reading symbols from=20
>>>>>>> /boot/kernel/ng_eiface.ko.symbols...done. Loaded symbols for
>>>>>>> /boot/kernel/ng_eiface.ko.symbols Reading symbols from=20
>>>>>>> /boot/kernel/ng_ether.ko.symbols...done. Loaded symbols for=20
>>>>>>> /boot/kernel/ng_ether.ko.symbols Reading symbols from=20
>>>>>>> /boot/kernel/accf_data.ko.symbols...done. Loaded symbols for
>>>>>>> /boot/kernel/accf_data.ko.symbols Reading symbols from=20
>>>>>>> /boot/kernel/accf_http.ko.symbols...done. Loaded symbols for
>>>>>>> /boot/kernel/accf_http.ko.symbols Reading symbols from=20
>>>>>>> /boot/kernel/ums.ko.symbols...done. Loaded symbols for=20
>>>>>>> /boot/kernel/ums.ko.symbols Reading symbols from=20
>>>>>>> /boot/kernel/ng_socket.ko.symbols...done. Loaded symbols for
>>>>>>> /boot/kernel/ng_socket.ko.symbols Reading symbols from=20
>>>>>>> /boot/kernel/fdescfs.ko.symbols...done. Loaded symbols for=20
>>>>>>> /boot/kernel/fdescfs.ko.symbols #0  doadump (textdump=3D1) at=20
>>>>>>> pcpu.h:219 219        __asm("movq %%gs:%1,%0" : "=3Dr" (td) (kgdb=
) bt
>>>>>>> #0 doadump (textdump=3D1) at pcpu.h:219 #1  0xffffffff8094b337
>>>>>>> in kern_reboot (howto=3D260) at
>>>>>>> /usr/src/sys/kern/kern_shutdown.c:451 #2 0xffffffff8094b845
>>>>>>> in vpanic (fmt=3D<value optimized out>, ap=3D<value optimized
>>>>>>> out>) at /usr/src/sys/kern/kern_shutdown.c:758 #3
>>>>>>> 0xffffffff8094b6d9 in kassert_panic (fmt=3D<value optimized
>>>>>>> out>) at /usr/src/sys/kern/kern_shutdown.c:646 #4
>>>>>>> 0xffffffff80b1ee59 in tcp_usr_detach (so=3D<value optimized
>>>>>>> out>) at /usr/src/sys/netinet/tcp_usrreq.c:202 #5
>>>>>>> 0xffffffff809cd291 in sofree (so=3D0xfffff801dd302000) at=20
>>>>>>> /usr/src/sys/kern/uipc_socket.c:747 #6  0xffffffff809cdb00 in
>>>>>>> soclose (so=3D<value optimized out>) at=20
>>>>>>> /usr/src/sys/kern/uipc_socket.c:849 #7  0xffffffff808fe659 in
>>>>>>> _fdrop (fp=3D0xfffff802a593db40, td=3D0x0) at file.h:343 #8=20
>>>>>>> 0xffffffff80901092 in closef (fp=3D0xfffff802a593db40,=20
>>>>>>> td=3D0xfffff80eebc894a0) at
>>>>>>> /usr/src/sys/kern/kern_descrip.c:2338 #9 0xffffffff808feb5d
>>>>>>> in closefp (fdp=3D0xfffff80b20cce000, fd=3D<value optimized out>,=

>>>>>>> fp=3D0xfffff802a593db40, td=3D0xfffff80eebc894a0,
>>>>>>> holdleaders=3D<value optimized out>) at=20
>>>>>>> /usr/src/sys/kern/kern_descrip.c:1194 #10 0xffffffff80d7bc3a
>>>>>>> in amd64_syscall (td=3D0xfffff80eebc894a0, traced=3D0) at=20
>>>>>>> subr_syscall.c:134 #11 0xffffffff80d5f1db in Xfast_syscall ()
>>>>>>> at /usr/src/sys/amd64/amd64/exception.S:396 #12
>>>>>>> 0x0000000801c8d94a in ?? () Previous frame inner to this
>>>>>>> frame (corrupt stack?) Current language:  auto; currently
>>>>>>> minimal
>>>>>>
>>>>>> Thanks for the information.  As I suspected the initial error
>>>>>> was elsewhere than tcp_twclose(), never got this assertion
>>>>>> before:
>>>>>>
>>>>>> tcp_detach: INP_TIMEWAIT && INP_DROPPED && tp !=3D NULL
>>>>>>
>>>>>> from here:
>>>>>>
>>>>>> static void tcp_detach(struct socket *so, struct inpcb *inp) {
>>>>>> struct tcpcb *tp;
>>>>>>
>>>>>> INP_INFO_WLOCK_ASSERT(&V_tcbinfo); INP_WLOCK_ASSERT(inp);
>>>>>>
>>>>>> KASSERT(so->so_pcb =3D=3D inp, ("tcp_detach: so_pcb !=3D inp"));=20
>>>>>> KASSERT(inp->inp_socket =3D=3D so, ("tcp_detach: inp_socket !=3D
>>>>>> so"));
>>>>>>
>>>>>> tp =3D intotcpcb(inp);
>>>>>>
>>>>>> if (inp->inp_flags & INP_TIMEWAIT) { if (inp->inp_flags &=20
>>>>>> INP_DROPPED) { KASSERT(tp =3D=3D NULL, ("tcp_detach: INP_TIMEWAIT
>>>>>> && " "INP_DROPPED && tp !=3D NULL"));
>>>>>>
>>>>>> Let me check if I could find a path that could lead to this=20
>>>>>> unexpected case.  Unexpected because:  INP_DROPPED and=20
>>>>>> inp->inp_ppcb is set to NULL are set at same time here:
>>>>>>
>>>>>> void tcp_twclose(struct tcptw *tw, int reuse) { struct socket
>>>>>> *so; struct inpcb *inp;
>>>>>>
>>>>>> inp =3D tw->tw_inpcb; KASSERT((inp->inp_flags & INP_TIMEWAIT),=20
>>>>>> ("tcp_twclose: !timewait")); KASSERT(intotw(inp) =3D=3D tw,=20
>>>>>> ("tcp_twclose: inp_ppcb !=3D tw"));=20
>>>>>> INP_INFO_WLOCK_ASSERT(&V_tcbinfo);      /* in_pcbfree() */=20
>>>>>> INP_WLOCK_ASSERT(inp);
>>>>>>
>>>>>> tcp_tw_2msl_stop(tw, reuse); inp->inp_ppcb =3D NULL;=20
>>>>>> in_pcbdrop(inp); ...
>>>>>>
>>>>>> Interesting [...]
>>>
>>> Just a quick update. Julien is pursuing this off list with a core
>>> dump and we are now waiting for a new core dump with the first
>>> KASSERT removed. this is on a stable/10 kernel.
>>
>> By the way Palle could you also run below Dtrace script to see where
>> this tcp_close() in INP_TIMEWAIT comes from:
>>
>> $ cat tcp-close-tw.d
>> fbt::tcp_close:entry
>> /args[0]->t_inpcb->inp_flags & 0x01000000/
>> {
>>  @s1[stack()] =3D count()
>> }
>>
>> tick-1sec {
>> printa(@s1);
>> }
>> $ sudo dtrace -s tcp-close-tw.d
>>
>> And share any backtraces reported in this dtrace script output.
>>
>> George, could you check if this dtrace script makes sense for you, and=

>> if you have any improvements to add, I am quite a rookie in Dtrace scr=
ipts.
>=20
> Shall I let the dtrace script run continuously until the machine crashe=
s? Or just run it once?

 Continuously until the machine crashes.  You can report any backstrace
outputs like:

              kernel`tcp_usr_close+0x86
              kernel`soclose+0xe4
              kernel`_fdrop+0x29
              kernel`closef+0x237
              kernel`closefp+0x95
              kernel`amd64_syscall+0x357
              kernel`0xffffffff80c83c4b
                1

 before the machine crashes.   But I expect the problematic case
detection with Dtrace to be quickly followed by the crash.  Will see.

--
Julien


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