From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
"H. Peter Anvin" <hpa@zytor.com>,
Peter Zijlstra <peterz@infradead.org>,
Linux-Next Mailing List <linux-next@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Andy Lutomirski <luto@kernel.org>
Subject: Re: linux-next: manual merge of the rcu tree with the tip tree
Date: Tue, 1 Aug 2017 09:31:05 -0700 [thread overview]
Message-ID: <20170801163105.GY3730@linux.vnet.ibm.com> (raw)
In-Reply-To: <788306045.812.1501561556636.JavaMail.zimbra@efficios.com>
On Tue, Aug 01, 2017 at 04:25:56AM +0000, Mathieu Desnoyers wrote:
> ----- On Aug 1, 2017, at 12:03 AM, Paul E. McKenney paulmck@linux.vnet.ibm.com wrote:
>
> > On Tue, Aug 01, 2017 at 12:04:05AM +0000, Mathieu Desnoyers wrote:
> >> ----- On Jul 31, 2017, at 12:13 PM, Paul E. McKenney paulmck@linux.vnet.ibm.com
> >> wrote:
> >>
> >> > On Mon, Jul 31, 2017 at 01:50:29PM +1000, Stephen Rothwell wrote:
> >> >> Hi Paul,
> >> >>
> >> >> Today's linux-next merge of the rcu tree got a conflict in:
> >> >>
> >> >> arch/x86/mm/tlb.c
> >> >>
> >> >> between commit:
> >> >>
> >> >> 94b1b03b519b ("x86/mm: Rework lazy TLB mode and TLB freshness tracking")
> >> >>
> >> >> from the tip tree and commit:
> >> >>
> >> >> d7713e8f8b23 ("membarrier: Expedited private command")
> >> >>
> >> >> from the rcu tree.
> >> >>
> >> >> I fixed it up (the former removed the comment and the load_cr3(), so I
> >> >> just dropped the commend change in the latter) and can carry the fix as
> >> >> necessary. This is now fixed as far as linux-next is concerned, but any
> >> >> non trivial conflicts should be mentioned to your upstream maintainer
> >> >> when your tree is submitted for merging. You may also want to consider
> >> >> cooperating with the maintainer of the conflicting tree to minimise any
> >> >> particularly complex conflicts.
> >> >
> >> > Thank you, Stephen!
> >> >
> >> > Mathieu, Peter, our commit log reads as if removal of load_cr3() would
> >> > simply result in relying on the ordering provided by the atomic ops
> >> > in switch_mm() for mm_cpumask(), so that only the commit log and the
> >> > comment need changing.
> >> >
> >> > Please let me know if I am missing something here.
> >>
> >> I think you are right. Both load_cr3() and mm_cpumask update operations
> >> (LOCK prefixed) provide the appropriate barriers on x86. So it's just a
> >> matter of adapting the comment to the new reality.
> >
> > Like this?
>
> The updated comment in the commit message looks good, but I would be
> tempted to add a comment in x86 switch_mm_irqs_off() stating the
> following requirement just before the line invoking cpumask_set_cpu():
>
> /*
> * The full memory barrier implied by mm_cpumask update operations
> * is required by the membarrier system call.
> */
This looks good to me, but I will give the discussion another day or
so to settle out. ;-)
Thanx, Paul
next prev parent reply other threads:[~2017-08-01 16:31 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-31 3:50 linux-next: manual merge of the rcu tree with the tip tree Stephen Rothwell
2017-07-31 16:13 ` Paul E. McKenney
2017-08-01 0:04 ` Mathieu Desnoyers
2017-08-01 4:03 ` Paul E. McKenney
2017-08-01 4:25 ` Mathieu Desnoyers
2017-08-01 16:31 ` Paul E. McKenney [this message]
2017-08-01 13:43 ` Andy Lutomirski
2017-08-01 13:58 ` Peter Zijlstra
2017-08-01 14:15 ` Peter Zijlstra
2017-08-01 14:17 ` Andy Lutomirski
2017-08-01 14:02 ` Mathieu Desnoyers
2017-08-01 14:15 ` Andy Lutomirski
2017-08-01 15:40 ` Mathieu Desnoyers
2017-08-01 21:36 ` Paul E. McKenney
-- strict thread matches above, loose matches on Subject: below --
2024-02-27 1:55 Stephen Rothwell
2022-04-06 2:45 Stephen Rothwell
2022-04-06 16:28 ` Paul E. McKenney
2022-02-21 18:17 broonie
2021-10-12 4:48 Stephen Rothwell
2021-10-13 16:31 ` Paul E. McKenney
2021-08-17 7:09 Stephen Rothwell
2021-06-23 5:33 Stephen Rothwell
2021-06-22 4:51 Stephen Rothwell
2021-06-22 4:47 Stephen Rothwell
2021-06-22 5:04 ` Stephen Rothwell
2021-06-22 17:10 ` Paul E. McKenney
2020-10-09 4:59 Stephen Rothwell
2020-07-29 6:23 Stephen Rothwell
2020-06-26 3:14 Stephen Rothwell
2020-06-25 2:44 Stephen Rothwell
2020-06-25 3:44 ` Paul E. McKenney
2020-06-24 3:04 Stephen Rothwell
2020-06-24 4:06 ` Paul E. McKenney
2020-05-29 6:22 Stephen Rothwell
2020-05-29 6:41 ` Stephen Rothwell
2020-05-29 14:15 ` Paul E. McKenney
2020-05-29 23:38 ` Stephen Rothwell
2020-03-25 3:08 Stephen Rothwell
2020-03-25 3:18 ` Paul E. McKenney
2020-03-25 21:31 ` Paul E. McKenney
2019-12-19 0:50 Stephen Rothwell
2019-12-19 1:27 ` Paul E. McKenney
2019-12-19 1:31 ` Paul E. McKenney
2019-12-19 8:41 ` Peter Zijlstra
2019-12-19 13:38 ` Paul E. McKenney
2019-12-16 23:37 Stephen Rothwell
2018-06-22 2:27 Stephen Rothwell
2018-06-26 19:33 ` Paul E. McKenney
2017-11-10 2:14 Stephen Rothwell
2017-08-22 4:13 Stephen Rothwell
2016-07-18 5:26 Stephen Rothwell
2016-07-19 3:00 ` Paul E. McKenney
2016-06-09 5:14 Stephen Rothwell
2016-06-09 15:59 ` Paul E. McKenney
2016-03-04 4:13 Stephen Rothwell
2016-03-04 15:04 ` Paul E. McKenney
2015-07-16 2:57 Stephen Rothwell
2015-05-07 3:56 Stephen Rothwell
2014-02-24 4:18 Stephen Rothwell
2014-02-24 4:42 ` Paul E. McKenney
2012-09-05 3:59 Stephen Rothwell
2012-09-05 16:39 ` Paul E. McKenney
2012-09-05 17:11 ` Peter Zijlstra
2012-08-23 3:01 Stephen Rothwell
2012-08-23 3:22 ` Paul E. McKenney
2012-08-22 4:27 Stephen Rothwell
2012-08-22 5:05 ` Paul E. McKenney
2012-08-22 4:27 Stephen Rothwell
2012-08-22 5:03 ` Paul E. McKenney
2011-06-20 4:47 Stephen Rothwell
2011-06-20 15:17 ` Paul E. McKenney
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