linux-kernel - Re: [PATCH 1/5] sched/deadline: Fix double accounting of rq/running bw in push_dl

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 31 Jul 2019 11:32:58 +0100
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     luca abeni <luca.abeni@...tannapisa.it>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Valentin Schneider <Valentin.Schneider@....com>,
        Qais Yousef <Qais.Yousef@....com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/5] sched/deadline: Fix double accounting of rq/running
 bw in push_dl_task()

On 7/29/19 10:00 AM, Dietmar Eggemann wrote:
> On 7/26/19 2:30 PM, luca abeni wrote:
>> Hi,
>>
>> On Fri, 26 Jul 2019 09:27:52 +0100
>> Dietmar Eggemann <dietmar.eggemann@....com> wrote:
>> [...]
>>> @@ -2121,17 +2121,13 @@ static int push_dl_task(struct rq *rq)
>>>  	}
>>>  
>>>  	deactivate_task(rq, next_task, 0);
>>> -	sub_running_bw(&next_task->dl, &rq->dl);
>>> -	sub_rq_bw(&next_task->dl, &rq->dl);
>>>  	set_task_cpu(next_task, later_rq->cpu);
>>> -	add_rq_bw(&next_task->dl, &later_rq->dl);
>>>  
>>>  	/*
>>>  	 * Update the later_rq clock here, because the clock is used
>>>  	 * by the cpufreq_update_util() inside __add_running_bw().
>>>  	 */
>>>  	update_rq_clock(later_rq);
>>> -	add_running_bw(&next_task->dl, &later_rq->dl);
>>
>> Looking at the code again and thinking a little bit more about this
>> issue, I suspect a similar change is needed in pull_dl_task() too, no?
> 
> The code looks the same. Let me try to test it. I will add it in v2 then.

Like you expected, it happens on the pull side as well.

[  129.813720] --> CPU7: pull_dl_task: p=[thread0-6 1313] dl_bw=125829
src_rq->dl.running_bw=251658 this_rq->dl.running_bw=125829
[  129.825167] <-- CPU7: pull_dl_task: p=[thread0-6 1313] dl_bw=125829
src_rq->dl.running_bw=0 this_rq->dl.running_bw=377487
...
[  129.948528] dl_rq->running_bw > old
[  129.948568] WARNING: CPU: 7 PID: 0 at kernel/sched/deadline.c:117
inactive_task_timer+0x5e8/0x6b8
...
[  130.077158]  inactive_task_timer+0x5e8/0x6b8
[  130.081427]  __hrtimer_run_queues+0x12c/0x398
[  130.085782]  hrtimer_interrupt+0xfc/0x330
...