linux-kernel - Re: [PATCH v3 1/3] sched/cpuacct: fix charge percpu cpuusage

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Message-ID: <YhUlD+NUMYdKB40J@slm.duckdns.org>
Date:   Tue, 22 Feb 2022 08:01:51 -1000
From:   Tejun Heo <tj@...nel.org>
To:     Chengming Zhou <zhouchengming@...edance.com>
Cc:     mingo@...hat.com, peterz@...radead.org, vincent.guittot@...aro.org,
        bristot@...hat.com, zhaolei@...fujitsu.com,
        lizefan.x@...edance.com, hannes@...xchg.org,
        linux-kernel@...r.kernel.org, Minye Zhu <zhuminye@...edance.com>
Subject: Re: [PATCH v3 1/3] sched/cpuacct: fix charge percpu cpuusage

On Sun, Feb 20, 2022 at 01:14:24PM +0800, Chengming Zhou wrote:
> The cpuacct_account_field() is always called by the current task
> itself, so it's ok to use __this_cpu_add() to charge the tick time.
> 
> But cpuacct_charge() maybe called by update_curr() in load_balance()
> on a random CPU, different from the CPU on which the task is running.
> So __this_cpu_add() will charge that cputime to a random incorrect CPU.
> 
> Fixes: 73e6aafd9ea8 ("sched/cpuacct: Simplify the cpuacct code")
> Reported-by: Minye Zhu <zhuminye@...edance.com>
> Signed-off-by: Chengming Zhou <zhouchengming@...edance.com>

For all three patches,

Acked-by: Tejun Heo <tj@...nel.org>

Thanks.

-- 
tejun