Re: Bug#983379: linux uml segfault

From: Anton Ivanov <anton.ivanov@kot-begemot.co.uk>
To: rrs@debian.org, 983379@bugs.debian.org,
	Christopher Obbard <chris.obbard@collabora.com>,
	"linux-um@lists.infradead.org" <linux-um@lists.infradead.org>
Subject: Re: Bug#983379: linux uml segfault
Date: Wed, 3 Mar 2021 10:53:35 +0000	[thread overview]
Message-ID: <7e9a6d29-dc99-0d4f-45f6-4cf1b35935fb@kot-begemot.co.uk> (raw)
In-Reply-To: <e86375146432f4fa12da18525d99c56292af72ac.camel@debian.org>

On 03/03/2021 10:45, Ritesh Raj Sarraf wrote:
> HI Anton,
>
> On Wed, 2021-03-03 at 09:30 +0000, Anton Ivanov wrote:
>>> OTOH, I have one more user (other than you) who's not been able to
>>> reproduce the issue.
>>>
>>>> I will do a dissect the moment I figure out how to reproduce it.
>>>> I
>>>> will try to do some more experiments on that tomorrow.
>> I tried to alter the userspace a bit, but it makes no difference.
>>
>> Out of curiosity, what are you running it on?
>>
> Bare-metal machines. 3 different machines, all Intel processors.
> And it fails on all 3 of them.

Hmmm...

All mine are AMD. I can try to boot up an Intel later today with Bullseye to see if it makes a difference.

> On the distribution side, all 3 of them run Debian Unstable, with Linux
> 5.10.13
>
>> The code here is:
>>
>> static inline u32 printk_caller_id(void)
>> {
>>          return in_task() ? task_pid_nr(current) :
>>                  0x80000000 + raw_smp_processor_id();
>> }
>>
>>
>> That is something which should not bomb out unless we have memory
>> corruption or something along those lines - current being invalid.
>>
> Must be something different. Not all machines could have bad memory at
> the same time.

I did not mean bad memory. I meant memory corruption as a result of race, buffer overrun or anything else like that.

>
>
-- 
Anton R. Ivanov
https://www.kot-begemot.co.uk/

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