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Subject: Re: WARNING at switch_mm_irqs_off, followed by frozen machine
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     linux-kernel@vger.kernel.org, riel@surriel.com, luto@kernel.org,
        x86@kernel.org
References: <c060d969-beb1-f99b-ab56-d2e9fd85c5dc@pp.inet.fi>
 <20200618102135.GA616959@hirez.programming.kicks-ass.net>
From:   Ilkka Prusi <ilkka.prusi@pp.inet.fi>
Message-ID: <b532d1be-221c-865a-c400-0b8b6273b489@pp.inet.fi>
Date:   Sat, 20 Jun 2020 03:59:43 +0300
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Hi,

On 18.6.2020 13.21, Peter Zijlstra wrote:
> On Wed, Jun 17, 2020 at 02:32:39AM +0300, Ilkka Prusi wrote:
>> Hi,
>>
>> Yesterday my computer with kernel version 5.7.2 was frozen badly enough that
>> hard reset was necessary (did not react to SysRq keys). Upon checking logs I
>> found following warning and information from the time just before resetting
>> it.
>>
>> Computer has AMD Ryzen 7 2700, Asus B450 motherboard.
>>
>> 5.8-rc1 encountered BUG() and did not boot (iommu and smp_processor_id()
>> called from wrong context, I'll see if I can catch log somehow).
> Since you're building your own kernels, can you make sure to always
> have:
>
>   - CONFIG_DEBUG_BUGVERBOSE=y
>   - CONFIG_DEBUG_INFO=y
>
> and then when reporting, run the thing through:
>
>    ./scripts/decode_stacktrace.sh

Ok, thanks for letting me know, I'll try that.


> And then pattern match that against my local defconfig build of
> arch/x86/mm/tlb.o and pray my compiler did anyting like your
> (unspecified) compiler.

Forgot to mention that, currently it is:

gcc (Debian 9.3.0-13) 9.3.0

I'll try your suggestions, sorry for not replying sooner.

--

  - Ilkka Prusi