Re: [PATCH v26 00/10] Simple Donor Migration for Proxy Execution

[K Prateek Nayak]

Hello John,

On 4/4/2026 5:56 AM, John Stultz wrote:
> I'm currently testing with my best guess of the combined suggestions
> you've both tossed into this thread. Unfortunately I still trip over
> state == TASK_RUNNING in proxy_deactivate(), so I'm trying to debug
> that now.
> (I think the issue is we hit the ttwu_queue_wakelist() case without
> clearing PROXY_WAKING, so we need to clear_task_blocked_on() earlier
> in ttwu, likely right after setting TASK_WAKING - that's looking ok so
> far).

That makes sense! I forgot we had that path for "p->on_cpu". Thank you
for chasing that.

Also looking at proxy-exec-v27-WIP, I think that:

    set_task_blocked_on_waking(p, NULL)

in try_to_wake_up() can be moved after ttwu_state_match() since
otherwise, we skip waking the task but ttwu() will end up marking
it PROXY_WAKING for a spurious wakeup.

I don't think there is any harm in keeping it that way but during the
next pick, __schedule() will end up seeing PROXY_WAKING and will block
the task.

Until it receives a genuine wakeup, it cannot participate in proxy which
is a missed opportunity.

> 
> After I get this into a stable state, I'll try to polish it up a bit
> and then re-layer the rest of the proxy-exec series on top (I do fret
> the sleeping owner enqueueing will be more complicated).

Ack! Let me go stare at it for a while but since you say it hasn't
outright crashed your system, you may have taken care of everything
already ;-)

-- 
Thanks and Regards,
Prateek