linux-kernel - Re: SCHED_DEADLINE tasks missing their deadline with SCHED_FLAG

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Message-ID: <aFvLYv0xSXxoyZZ8@jlelli-thinkpadt14gen4.remote.csb>
Date: Wed, 25 Jun 2025 12:11:46 +0200
From: Juri Lelli <juri.lelli@...hat.com>
To: luca abeni <luca.abeni@...tannapisa.it>
Cc: Marcel Ziswiler <marcel.ziswiler@...ethink.co.uk>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Vineeth Pillai <vineeth@...byteword.org>
Subject: Re: SCHED_DEADLINE tasks missing their deadline with
 SCHED_FLAG_RECLAIM jobs in the mix (using GRUB)

On 25/06/25 11:30, Juri Lelli wrote:

...

> It looks like (at least at my end) it comes from
> 
> task_non_contending()
>   sub_running_bw()
>     __sub_running_bw()
>       WARN_ON_ONCE(dl_rq->running_bw > old); /* underflow */
> 
> I would guess the later initialization of dl-server is not playing well
> wrt running_bw. Will take a look.

I pushed another fixup adding a check for dl_server_active in
dl_server_stop(). It seems to cure the WARN here.

Could you please pull and re-test?