linux-kernel - Re: [PATCH] sched/fair: Update min_vruntime for reweight

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] [day] [month] [year] [list]

Message-ID: <96194f8a-4e3f-4563-83d0-c754e1d2abd3@bytedance.com>
Date:   Fri, 17 Nov 2023 15:34:05 +0800
From:   Abel Wu <wuyun.abel@...edance.com>
To:     Yiwei Lin <s921975628@...il.com>, mingo@...hat.com,
        peterz@...radead.org
Cc:     vincent.guittot@...aro.org, dietmar.eggemann@....com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sched/fair: Update min_vruntime for reweight_entity()
 correctly

On 11/16/23 7:52 PM, Abel Wu Wrote:
> Please add a Fix tag like this:
> 
> Fixes: eab03c23c2a1 ("sched/eevdf: Fix vruntime adjustment on reweight")

Can you resend this patch with this fix tag please?

> 
> On 11/16/23 7:42 PM, Yiwei Lin Wrote:
>> Since reweight_entity() may have chance to change the weight of
>> cfs_rq->curr entity, we should also update_min_vruntime() if
>> this is the case
>>
>> Signed-off-by: Yiwei Lin <s921975628@...il.com>
>> ---
>>   kernel/sched/fair.c | 20 ++++++++++----------
>>   1 file changed, 10 insertions(+), 10 deletions(-)
>>
>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
>> index 07f555857..6fb89f4a3 100644
>> --- a/kernel/sched/fair.c
>> +++ b/kernel/sched/fair.c
>> @@ -3815,17 +3815,17 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
>>       enqueue_load_avg(cfs_rq, se);
>>       if (se->on_rq) {
>>           update_load_add(&cfs_rq->load, se->load.weight);
>> -        if (!curr) {
>> -            /*
>> -             * The entity's vruntime has been adjusted, so let's check
>> -             * whether the rq-wide min_vruntime needs updated too. Since
>> -             * the calculations above require stable min_vruntime rather
>> -             * than up-to-date one, we do the update at the end of the
>> -             * reweight process.
>> -             */
>> +        if (!curr)
>>               __enqueue_entity(cfs_rq, se);
>> -            update_min_vruntime(cfs_rq);
>> -        }
>> +
>> +        /*
>> +         * The entity's vruntime has been adjusted, so let's check
>> +         * whether the rq-wide min_vruntime needs updated too. Since
>> +         * the calculations above require stable min_vruntime rather
>> +         * than up-to-date one, we do the update at the end of the
>> +         * reweight process.
>> +         */
>> +        update_min_vruntime(cfs_rq);
>>       }
>>   }
> 
> LGTM, thanks!