Re: [PATCH 1/3 RESEND] sched: Remove __rcu annotation from cred pointer

From: Amol Grover <frextrite@gmail.com>
To: Richard Guy Briggs <rgb@redhat.com>
Cc: 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>,
	Paul Moore <paul@paul-moore.com>, 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
Subject: Re: [PATCH 1/3 RESEND] sched: Remove __rcu annotation from cred pointer
Date: Mon, 25 May 2020 23:34:21 +0530	[thread overview]
Message-ID: <20200525180421.GA19@workstation-LAP.localdomain> (raw)
In-Reply-To: <20200525131741.s6lgb263fpo5uszk@madcap2.tricolour.ca>

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.

Thanks
Amol

> > Thanks
> > Amol
> 
> - RGB
> 
> --
> Richard Guy Briggs <rgb@redhat.com>
> Sr. S/W Engineer, Kernel Security, Base Operating Systems
> Remote, Ottawa, Red Hat Canada
> IRC: rgb, SunRaycer
> Voice: +1.647.777.2635, Internal: (81) 32635
> 