Kernel panics in tcp_twclose
Julien Charbon
jch at freebsd.org
Wed Sep 23 18:01:57 UTC 2015
Hi Palle, Hi George,
On 23/09/15 16:36, Palle Girgensohn wrote:
>> 22 sep 2015 kl. 23:59 skrev Julien Charbon <jch at freebsd.org>: On
>> 22/09/15 22:58, Palle Girgensohn wrote:
>>>> 22 sep 2015 kl. 20:16 skrev Julien Charbon <jch at freebsd.org>:
>>>> On 22/09/15 18:49, Palle Girgensohn wrote:
>>>>>> 22 sep 2015 kl. 18:46 skrev Palle Girgensohn
>>>>>> <girgen at FreeBSD.org>:
>>>>>>> 21 sep 2015 kl. 15:53 skrev Palle Girgensohn
>>>>>>> <girgen at FreeBSD.org>:
>>>>>>>> 21 sep 2015 kl. 10:21 skrev Julien Charbon
>>>>>>>> <jch at 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
>>>>>>>> kernel with these options:
>>>>>>>>
>>>>>>>> options DDB options DEADLKRES options
>>>>>>>> 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"
>>>>>>> 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]
>>>>> Copyright 2004 Free Software Foundation, Inc. GDB is free
>>>>> 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 != NULL cpuid =
>>>>> 16 KDB: stack backtrace: db_trace_self_wrapper() at
>>>>> db_trace_self_wrapper+0x2b/frame 0xfffffe183d9e97e0
>>>>> 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
>>>>> amd64_syscall+0x25a/frame 0xfffffe183d9e9bf0 Xfast_syscall()
>>>>> at Xfast_syscall+0xfb/frame 0xfffffe183d9e9bf0 --- syscall
>>>>> (6, FreeBSD ELF64, sys_close), rip = 0x801c8d94a, rsp =
>>>>> 0x7ffff91c8668, rbp = 0x7ffff91c8680 --- KDB: enter: panic
>>>>> Uptime: 18h57m59s Dumping 23085 out of 98263
>>>>> MB:..1%..11%..21%..31%..41%..51%..61%..71%..81%..91%
>>>>>
>>>>> Reading symbols from /boot/kernel/nullfs.ko.symbols...done.
>>>>> 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
>>>>> /boot/kernel/netgraph.ko.symbols...done. Loaded symbols for
>>>>> /boot/kernel/netgraph.ko.symbols Reading symbols from
>>>>> /boot/kernel/ng_eiface.ko.symbols...done. Loaded symbols for
>>>>> /boot/kernel/ng_eiface.ko.symbols Reading symbols from
>>>>> /boot/kernel/ng_ether.ko.symbols...done. Loaded symbols for
>>>>> /boot/kernel/ng_ether.ko.symbols Reading symbols from
>>>>> /boot/kernel/accf_data.ko.symbols...done. Loaded symbols for
>>>>> /boot/kernel/accf_data.ko.symbols Reading symbols from
>>>>> /boot/kernel/accf_http.ko.symbols...done. Loaded symbols for
>>>>> /boot/kernel/accf_http.ko.symbols Reading symbols from
>>>>> /boot/kernel/ums.ko.symbols...done. Loaded symbols for
>>>>> /boot/kernel/ums.ko.symbols Reading symbols from
>>>>> /boot/kernel/ng_socket.ko.symbols...done. Loaded symbols for
>>>>> /boot/kernel/ng_socket.ko.symbols Reading symbols from
>>>>> /boot/kernel/fdescfs.ko.symbols...done. Loaded symbols for
>>>>> /boot/kernel/fdescfs.ko.symbols #0 doadump (textdump=1) at
>>>>> pcpu.h:219 219 __asm("movq %%gs:%1,%0" : "=r" (td) (kgdb) bt
>>>>> #0 doadump (textdump=1) at pcpu.h:219 #1 0xffffffff8094b337
>>>>> in kern_reboot (howto=260) at
>>>>> /usr/src/sys/kern/kern_shutdown.c:451 #2 0xffffffff8094b845
>>>>> in vpanic (fmt=<value optimized out>, ap=<value optimized
>>>>> out>) at /usr/src/sys/kern/kern_shutdown.c:758 #3
>>>>> 0xffffffff8094b6d9 in kassert_panic (fmt=<value optimized
>>>>> out>) at /usr/src/sys/kern/kern_shutdown.c:646 #4
>>>>> 0xffffffff80b1ee59 in tcp_usr_detach (so=<value optimized
>>>>> out>) at /usr/src/sys/netinet/tcp_usrreq.c:202 #5
>>>>> 0xffffffff809cd291 in sofree (so=0xfffff801dd302000) at
>>>>> /usr/src/sys/kern/uipc_socket.c:747 #6 0xffffffff809cdb00 in
>>>>> soclose (so=<value optimized out>) at
>>>>> /usr/src/sys/kern/uipc_socket.c:849 #7 0xffffffff808fe659 in
>>>>> _fdrop (fp=0xfffff802a593db40, td=0x0) at file.h:343 #8
>>>>> 0xffffffff80901092 in closef (fp=0xfffff802a593db40,
>>>>> td=0xfffff80eebc894a0) at
>>>>> /usr/src/sys/kern/kern_descrip.c:2338 #9 0xffffffff808feb5d
>>>>> in closefp (fdp=0xfffff80b20cce000, fd=<value optimized out>,
>>>>> fp=0xfffff802a593db40, td=0xfffff80eebc894a0,
>>>>> holdleaders=<value optimized out>) at
>>>>> /usr/src/sys/kern/kern_descrip.c:1194 #10 0xffffffff80d7bc3a
>>>>> in amd64_syscall (td=0xfffff80eebc894a0, traced=0) at
>>>>> 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 != 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 == inp, ("tcp_detach: so_pcb != inp"));
>>>> KASSERT(inp->inp_socket == so, ("tcp_detach: inp_socket !=
>>>> so"));
>>>>
>>>> tp = intotcpcb(inp);
>>>>
>>>> if (inp->inp_flags & INP_TIMEWAIT) { if (inp->inp_flags &
>>>> INP_DROPPED) { KASSERT(tp == NULL, ("tcp_detach: INP_TIMEWAIT
>>>> && " "INP_DROPPED && tp != NULL"));
>>>>
>>>> Let me check if I could find a path that could lead to this
>>>> unexpected case. Unexpected because: INP_DROPPED and
>>>> 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 = tw->tw_inpcb; KASSERT((inp->inp_flags & INP_TIMEWAIT),
>>>> ("tcp_twclose: !timewait")); KASSERT(intotw(inp) == tw,
>>>> ("tcp_twclose: inp_ppcb != tw"));
>>>> INP_INFO_WLOCK_ASSERT(&V_tcbinfo); /* in_pcbfree() */
>>>> INP_WLOCK_ASSERT(inp);
>>>>
>>>> tcp_tw_2msl_stop(tw, reuse); inp->inp_ppcb = NULL;
>>>> 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()] = 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 scripts.
> This is a really big problem for us now, 100k+ users use these
> systems... Would anyone suggest any paralell routes here to speed up
> the process of finding the culprit?
I agree, this issue is a complex one, more eyeballs/propositions would
be great.
Thanks.
--
Julien
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