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Date: Wed, 30 Aug 2017 18:10:24 -0700
From: Tejun Heo <tj@kernel.org>
To: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: lizefan@huawei.com, mingo@kernel.org, longman@redhat.com,
        akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
        sramana@codeaurora.org, prsood@codeaurora.org
Subject: Re: [PATCH] cgroup: Fix potential race between cgroup_exit and
 cpuset_attach
Message-ID: <20170831011024.GC491396@devbig577.frc2.facebook.com>
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Hello,

On Wed, Aug 30, 2017 at 06:23:50PM +0530, Neeraj Upadhyay wrote:
> cpuset_hotplug_workfn()
>   cgroup_transfer_tasks()
>     cgroup_migrate()
>       cgroup_migrate_execute()
>           <TASK EXIT>
>           list_del_init(&task->cg_list)
>         cpuset_attach()
>           cgroup_taskset_first(tset, &css) // css is not set
>           guarantee_online_mems(cs, ...) // data abort

I don't think this can happen anymore.  We lock out task exits during
migration and don't call migration callbacks if there's no tasks to
migrate.

Thanks.

-- 
tejun