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Date:   Fri, 1 Jun 2018 12:16:52 -0700
From:   Tejun Heo <tj@kernel.org>
To:     "Eric W. Biederman" <ebiederm@xmission.com>
Cc:     Michal Hocko <mhocko@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Kirill Tkhai <ktkhai@virtuozzo.com>, peterz@infradead.org,
        viro@zeniv.linux.org.uk, mingo@kernel.org,
        paulmck@linux.vnet.ibm.com, keescook@chromium.org, riel@redhat.com,
        tglx@linutronix.de, kirill.shutemov@linux.intel.com,
        marcos.souza.org@gmail.com, hoeun.ryu@gmail.com,
        pasha.tatashin@oracle.com, gs051095@gmail.com, dhowells@redhat.com,
        rppt@linux.vnet.ibm.com, linux-kernel@vger.kernel.org,
        Balbir Singh <balbir@linux.vnet.ibm.com>,
        Oleg Nesterov <oleg@redhat.com>
Subject: Re: [RFC][PATCH 1/2] memcg: Ensure every task that uses an mm is in
 the same memory cgroup
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Hello,

On Fri, Jun 01, 2018 at 01:11:59PM -0500, Eric W. Biederman wrote:
> Widening the definition of a process sounds good.  The memory control
> group code would still need a way to forbid these in cgroup v1 mode,
> when someone uses the task file.

Yeap, you're right.  We'll need memcg's can_attach rejecting for v1.

> Using widening instead of denying should reduce the risk of introducing
> a regression.
> 
> The only reason I support the crazy case in my earlier patch is so that
> we can have this discussion and in case we do cause a regression with
> this change the previous algorithmic cleanup won't have to be reverted
> as well.

Yeah, sure thing.

Thanks a lot.

-- 
tejun