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Date:   Tue, 22 Mar 2022 14:01:26 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Chengming Zhou <zhouchengming@bytedance.com>
Cc:     mingo@redhat.com, acme@kernel.org, mark.rutland@arm.com,
        alexander.shishkin@linux.intel.com, jolsa@kernel.org,
        namhyung@kernel.org, eranian@google.com,
        linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
        duanxiongchun@bytedance.com, songmuchun@bytedance.com
Subject: Re: [PATCH v2 2/6] perf/core: Introduce percpu perf_cgroup
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References: <20220322120834.98637-1-zhouchengming@bytedance.com>
 <20220322120834.98637-3-zhouchengming@bytedance.com>
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On Tue, Mar 22, 2022 at 08:08:30PM +0800, Chengming Zhou wrote:
> Although we don't have incosistency problem any more, we can
> have other problem like:
> 
> CPU1					CPU2
> (in context_switch)			(attach running task)
> 					prev->cgroups = cgrp2
> perf_cgroup_sched_switch(prev, next)
> 	cgrp2 == cgrp2 is True
> 

Again, I'm not following, how can you attach to a running task from
another CPU ?