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From:   Paul Moore <paul@paul-moore.com>
Date:   Tue, 26 May 2020 08:34:33 -0400
Message-ID: <CAHC9VhQ_jNbNFChy3i6AfmOkEQtER_pxrd5uCJwpfNeedyUM4Q@mail.gmail.com>
Subject: Re: [PATCH 1/3 RESEND] sched: Remove __rcu annotation from cred pointer
To:     Amol Grover <frextrite@gmail.com>
Cc:     Richard Guy Briggs <rgb@redhat.com>,
        Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
        James Morris <jamorris@linux.microsoft.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Jann Horn <jannh@google.com>,
        David Howells <dhowells@redhat.com>,
        Shakeel Butt <shakeelb@google.com>,
        "Eric W . Biederman" <ebiederm@xmission.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Eric Paris <eparis@redhat.com>,
        "Paul E . McKenney" <paulmck@kernel.org>,
        linux-kernel@vger.kernel.org,
        Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>,
        linux-audit@redhat.com, Joel Fernandes <joel@joelfernandes.org>,
        linux-kernel-mentees@lists.linuxfoundation.org
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On Mon, May 25, 2020 at 2:04 PM Amol Grover <frextrite@gmail.com> wrote:
> On Mon, May 25, 2020 at 09:17:41AM -0400, Richard Guy Briggs wrote:
> > On 2020-05-24 13:41, Amol Grover wrote:
> > > 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@google.com>
> > > > Co-developed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
> > > > Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
> > > > Signed-off-by: Amol Grover <frextrite@gmail.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.
> >
> > I asked on April 3 which upstream tree you expect this patchset to go
> > through and I did not see a reply.  Do you have a specific target or is
> > the large addressee list assuming someone else is taking this set?  All
> > we have seen is that it is not intended to go through the audit tree.
> >
>
> Apologies for it. As Paul Moore replied, initially I assumed this
> patchset to not go through the audit tree as the audit specific changes
> were secondary to the main change (though certainly I did not think
> which upstream tree the patchset would go through). But now I am okay
> with the patchset making it to upstream via audit tree if it is fine by
> the maintainers.

This patchset is not appropriate for the audit tree as the most
significant changes are not audit related.

My ACK on patch 3/3 was, and is, conditional on the previous patches
being acceptable to the greater kernel community; this is the main
reason why I didn't ACK patch 1/3 or 2/3.

-- 
paul moore
www.paul-moore.com