[gentoo-user] Re: Troubshooting AMD Radeon Vega system freeze [SOLVED]

[Grant Edwards <grant.b.edwards@gmail.com>]

On 2025-01-27, Grant Edwards <grant.b.edwards@gmail.com> wrote:
> On 2025-01-26, Grant Edwards <grant.b.edwards@gmail.com> wrote:
>>>> On 2025-01-25, Grant Edwards <grant.b.edwards@gmail.com> wrote:
>>>>> Starting about a week ago, my AMD system (AMD Ryzen 5 3400G with
>>>>> Radeon Vega Graphics) has been freezing up multiple times per day --
>>>>> always when in active use with X11. Before that, it had been reliable
>>>>> since assembled (about 5 years ago).
>>>>>
> [...]
>>
>> I tried rolling back Xorg server, that didn't seem to help.
>>
>> Google has found reports of recent versions (24.3.x) of mesa being
>> blamed for problems like this.  I see in the logs that mesa got
>> upgraded from 24.2.8 to 24.3.3 on the 20th.  I've rolled that back, to
>> see if that helps.
>
> No freezes for over two days now (including a full day of work today).
>
> It's definitely mesa 24.3.3 that's causing the lockups.

[sort-of see below]

> Is this something that needs to be filed as a bug with Gentoo, or just upstream?

And I found an excellent thread discussing this problem:

  https://bbs.archlinux.org/viewtopic.php?id=301798

I also found threads in Ubuntu forums talking (I think) about the same
problem.  But, as usual, the quality of the info in the archlinux
forum is several orders of magnitude better than that in the Ubuntu
forums where it's the usual blind leading the blind 3 (million)
stooges routine.

Based on info in the Arch Linux thread above, it looks like the root
cause is a race condition in some kernel code that wasn't triggered
until mesa starting using some particular feature of the AMD GPU.
There seem to be some fixes/remediations proposed for both the kernel
and mesa, but nothing final. Apparently the race condition has been
there all along, but was only very rarely triggred before mesa 24.3.

There are also hints that a real fix might involve AMD GPU firmware
changes, which aren't going to happen.

--
Grant