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Date:      Thu, 5 Jul 2018 10:48:16 -0700
From:      Pete Wright <pete@nomadlogic.org>
To:        John Baldwin <jhb@FreeBSD.org>, Niclas Zeising <zeising+freebsd@daemonic.se>, "O. Hartmann" <ohartmann@walstatt.org>, FreeBSD Current <freebsd-current@FreeBSD.org>
Subject:   Re: atomic changes break drm-next-kmod?
Message-ID:  <eb84c2ed-1cd8-794f-9d5e-9454edeba4e4@nomadlogic.org>
In-Reply-To: <c459a76c-21a2-2510-54b1-d7edee6eaa1e@FreeBSD.org>
References:  <c640afcd-1fa4-a43e-5f36-f0bd11aad63d@protected-networks.net> <20180703170223.266dbf5b@thor.intern.walstatt.dynvpn.de> <cbd2d2f2-8ce4-871a-9aaf-75738d6c465b@daemonic.se> <ee0f7fce-7ce3-3784-f9e8-0f6862d59303@FreeBSD.org> <c7a3b447-00e9-8501-0484-841a371cfd62@nomadlogic.org> <bb2cac77-4bcd-c87c-9bc9-ce5f8ce1c726@nomadlogic.org> <845aca10-8c01-fa3b-087f-f957df4e7531@nomadlogic.org> <063ae5c3-0584-1284-dd9d-ab8b5790baf1@FreeBSD.org> <0bf8e57b-fdb4-4c1a-3d0d-a734f8187ca8@nomadlogic.org> <4c5411dd-9f6b-7245-6ade-e11040f74687@FreeBSD.org> <24f5d737-a205-6fcc-0a33-a84601d2ff7a@nomadlogic.org> <c459a76c-21a2-2510-54b1-d7edee6eaa1e@FreeBSD.org>

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On 07/05/2018 10:10, John Baldwin wrote:
> On 7/3/18 5:10 PM, Pete Wright wrote:
>>
>> On 07/03/2018 15:56, John Baldwin wrote:
>>> On 7/3/18 3:34 PM, Pete Wright wrote:
>>>> On 07/03/2018 15:29, John Baldwin wrote:
>>>>> That seems like kgdb is looking at the wrong CPU.  Can you use
>>>>> 'info threads' and look for threads not stopped in 'sched_switch'
>>>>> and get their backtraces?  You could also just do 'thread apply
>>>>> all bt' and put that file at a URL if that is easiest.
>>>>>
>>>> sure thing John - here's a gist of "thread apply all bt"
>>>>
>>>> https://gist.github.com/gem-pete/d8d7ab220dc8781f0827f965f09d43ed
>>> That doesn't look right at all.  Are you sure the kernel matches the
>>> vmcore?  Also, which kgdb version are you using?
>>>
>> yea i agree that doesn't look right at all.  here is my setup:
>>
>> $ which kgdb
>> /usr/bin/kgdb
>> $ kgdb
>> GNU gdb 6.1.1 [FreeBSD]
>> $ ls -lh /var/crash/vmcore.1
>> -rw-------  1 root  wheel   1.6G Jul  3 15:03 /var/crash/vmcore.1
>> $ ls -l /usr/lib/debug/boot/kernel/kernel.debug
>> -r-xr-xr-x  1 root  wheel  87840496 Jul  3 13:54
>> /usr/lib/debug/boot/kernel/kernel.debug
>>
>> and i invoke kgdb like so:
>> $ sudo kgdb /usr/lib/debug/boot/kernel/kernel.debug /var/crash/vmcore.1
>>
>> here's a gist of my full gdb session:
>> http://termbin.com/krsn
>>
>> dunno - maybe i have a bad core dump?  regardless, more than happy to
>> help so let me know if i should try anything else or patches etc..
> Can you try installing gdb from ports and using /usr/local/bin/kgdb?
>

that seems to have done the trick, at least the output looks more 
encouraging.

  --- trap 0, rip = 0, rsp = 0, rbp = 0 ---
KDB: enter: panic

__curthread () at ./machine/pcpu.h:231
231        __asm("movq %%gs:%1,%0" : "=r" (td)


here's my full kgdb session:
http://termbin.com/qa4f

i don't see any threads not in "sched_switch" though :(

-pete


-- 
Pete Wright
pete@nomadlogic.org
@nomadlogicLA




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