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Date:   Thu, 4 May 2023 14:29:45 +0200
From:   Oleg Nesterov <oleg@redhat.com>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Wander Lairson Costa <wander@redhat.com>,
        Ingo Molnar <mingo@redhat.com>,
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Subject: Re: [PATCH v7 2/3] sched/task: Add the put_task_struct_atomic_safe()
 function
Message-ID: <20230504122945.GA28757@redhat.com>
References: <20230425114307.36889-1-wander@redhat.com>
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On 05/04, Peter Zijlstra wrote:
>
> Urgh.. that's plenty horrible. And I'm sure everybody plus kitchen sink
> has already asked why can't we just rcu free the thing unconditionally.
>
> Google only found me an earlier version of this same patch set, but I'm
> sure we've had that discussion many times over the past several years.

Yes... see for example

https://lore.kernel.org/lkml/CAHk-=whtj+aSYftniMRG4xvFE8dmmYyrqcJyPmzStsfj5w9r=w@mail.gmail.com/

We already have an rcu pass before put_task_struct(zombie), see
put_task_struct_rcu_user(), another one look unfortunate.

Oleg.