From: Oleg Nesterov <oleg@redhat.com>
To: Jann Horn <jannh@google.com>
Cc: Joel Fernandes <joel@joelfernandes.org>,
"Paul E. McKenney" <paulmck@linux.ibm.com>,
Kees Cook <keescook@chromium.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
LKML <linux-kernel@vger.kernel.org>,
Android Kernel Team <kernel-team@android.com>,
Kernel Hardening <kernel-hardening@lists.openwall.com>,
Andrew Morton <akpm@linux-foundation.org>,
Matthew Wilcox <willy@infradead.org>,
Michal Hocko <mhocko@suse.com>,
"Reshetova, Elena" <elena.reshetova@intel.com>
Subject: Re: [PATCH] Convert struct pid count to refcount_t
Date: Thu, 28 Mar 2019 17:26:42 +0100 [thread overview]
Message-ID: <20190328162641.GC19441@redhat.com> (raw)
In-Reply-To: <CAG48ez1-3dLvzQoxxoUzTUq8dc1wwvwPBBxX_X9FWMscWTS-FQ@mail.gmail.com>
On 03/28, Jann Horn wrote:
>
> Since we're just talking about RCU stuff now, adding Paul McKenney to
> the thread.
Since you added Paul let me add more confusion to this thread ;)
There were some concerns about the lack of barriers in put_pid(), but I can't
find that old discussion and I forgot the result of that discussion...
Paul, could you confirm that this code
CPU_0 CPU_1
X = 1; if (READ_ONCE(Y))
mb(); X = 2;
Y = 1; BUG_ON(X != 2);
is correct? I think it is, control dependency pairs with mb(), right?
If not, then put_pid() needs atomic_read_acquire() as it was proposed in that
discussion.
Oleg.
next prev parent reply other threads:[~2019-03-28 16:26 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-27 14:53 [PATCH] Convert struct pid count to refcount_t Joel Fernandes (Google)
2019-03-28 0:06 ` Kees Cook
2019-03-28 0:59 ` Jann Horn
2019-03-28 2:34 ` Joel Fernandes
2019-03-28 2:57 ` Jann Horn
2019-03-28 14:37 ` Joel Fernandes
2019-03-28 15:17 ` Jann Horn
2019-03-28 16:26 ` Oleg Nesterov [this message]
2019-03-28 17:37 ` Paul E. McKenney
2019-03-29 17:32 ` Oleg Nesterov
2019-03-29 19:45 ` Alan Stern
2019-04-01 15:28 ` David Laight
2019-03-30 2:36 ` Joel Fernandes
2019-03-30 15:16 ` Alan Stern
2019-03-31 21:57 ` Paul E. McKenney
2019-03-31 21:55 ` Paul E. McKenney
2019-04-01 21:11 ` Joel Fernandes
2019-04-04 15:23 ` Paul E. McKenney
2019-04-04 16:01 ` Alan Stern
2019-04-04 18:08 ` Joel Fernandes
2019-04-04 18:19 ` Paul E. McKenney
2019-04-04 20:31 ` Joel Fernandes
2019-04-04 19:09 ` Alan Stern
2019-03-28 20:00 ` Joel Fernandes
2019-03-29 2:24 ` Joel Fernandes
2019-03-28 16:52 ` Kees Cook
2019-03-28 14:26 ` Oleg Nesterov
2019-03-28 14:39 ` Joel Fernandes
2019-03-29 2:34 ` Joel Fernandes
2019-03-29 17:37 ` Oleg Nesterov
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