linux-kernel - Re: [PATCH 1/3 RESEND] sched: Remove _

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Date:   Sun, 24 May 2020 13:41:17 +0530
From:   Amol Grover <frextrite@...il.com>
To:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        James Morris <jamorris@...ux.microsoft.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jann Horn <jannh@...gle.com>,
        David Howells <dhowells@...hat.com>,
        Shakeel Butt <shakeelb@...gle.com>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Paul Moore <paul@...l-moore.com>,
        Eric Paris <eparis@...hat.com>
Cc:     linux-kernel-mentees@...ts.linuxfoundation.org,
        linux-kernel@...r.kernel.org, linux-audit@...hat.com,
        Joel Fernandes <joel@...lfernandes.org>,
        Madhuparna Bhowmik <madhuparnabhowmik10@...il.com>,
        "Paul E . McKenney" <paulmck@...nel.org>
Subject: Re: [PATCH 1/3 RESEND] sched: Remove __rcu annotation from cred
 pointer

On Thu, Apr 02, 2020 at 11:26:38AM +0530, Amol Grover wrote:
> task_struct::cred (subjective credentials) is *always* used
> task-synchronously, hence, does not require RCU semantics.
> 
> task_struct::real_cred (objective credentials) can be used in
> RCU context and its __rcu annotation is retained.
> 
> However, task_struct::cred and task_struct::real_cred *may*
> point to the same object, hence, the object pointed to by
> task_struct::cred *may* have RCU delayed freeing.
> 
> Suggested-by: Jann Horn <jannh@...gle.com>
> Co-developed-by: Joel Fernandes (Google) <joel@...lfernandes.org>
> Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
> Signed-off-by: Amol Grover <frextrite@...il.com>

Hello everyone,

Could you please go through patches 1/3 and 2/3 and if deemed OK, give
your acks. I sent the original patch in beginning of February (~4 months
back) and resent the patches again in beginning of April due to lack of
traffic. Paul Moore was kind enough to ack twice - the 3/3 and its
resend patch. However these 2 patches still remain. I'd really
appreciate if someone reviewed them.

Thanks
Amol