All of lore.kernel.org
 help / color / mirror / Atom feed
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: paulmck <paulmck@linux.ibm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	"Russell King, ARM Linux" <linux@armlinux.org.uk>,
	Chris Metcalf <cmetcalf@ezchip.com>, Chris Lameter <cl@linux.com>,
	Kirill Tkhai <tkhai@yandex.ru>, Mike Galbraith <efault@gmx.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>
Subject: Re: [RFC PATCH 1/2] Fix: sched/membarrier: p->mm->membarrier_state racy load
Date: Sun, 8 Sep 2019 09:46:04 -0400 (EDT)	[thread overview]
Message-ID: <509773035.243.1567950364367.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <20190904111126.GB24568@redhat.com>

----- On Sep 4, 2019, at 12:11 PM, Oleg Nesterov oleg@redhat.com wrote:

> with or without these changes...
> 
> Why do membarrier_register_*_expedited() check get_nr_threads() == 1?
> This makes no sense to me, atomic_read(mm_users) == 1 should be enough.
> 
> 
> And I am not sure I understand membarrier_mm_sync_core_before_usermode().
> OK, membarrier_private_expedited() can race with user -> kernel -> user
> transition, but we do not care unless both user's above have the same mm?
> Shouldn't membarrier_mm_sync_core_before_usermode() do
> 
>	if (current->mm != mm)
>		return;
> 
> at the start to make it more clear and avoid sync_core_before_usermode()
> if possible?

I think I missed replying to your email. Indeed, you are right, I've added
2 cleanup patches taking care of this in my latest round.

Thanks,

Mathieu


-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com

      parent reply	other threads:[~2019-09-08 13:46 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-03 20:11 [RFC PATCH 1/2] Fix: sched/membarrier: p->mm->membarrier_state racy load Mathieu Desnoyers
2019-09-03 20:11 ` [RFC PATCH 2/2] Fix: sched/membarrier: private expedited registration check Mathieu Desnoyers
2019-09-03 20:24 ` [RFC PATCH 1/2] Fix: sched/membarrier: p->mm->membarrier_state racy load Peter Zijlstra
2019-09-03 20:36   ` Linus Torvalds
2019-09-04 15:19     ` Mathieu Desnoyers
2019-09-04 16:09       ` Peter Zijlstra
2019-09-04 17:12         ` Mathieu Desnoyers
2019-09-04 18:26           ` Peter Zijlstra
2019-09-06  0:51             ` Mathieu Desnoyers
2019-09-03 20:41   ` Mathieu Desnoyers
2019-09-04 11:28     ` Peter Zijlstra
2019-09-04 11:49       ` Peter Zijlstra
2019-09-04 15:26         ` Mathieu Desnoyers
2019-09-04 12:03       ` Oleg Nesterov
2019-09-04 12:43         ` Peter Zijlstra
2019-09-04 13:17           ` Oleg Nesterov
2019-09-03 20:27 ` Linus Torvalds
2019-09-03 20:53   ` Mathieu Desnoyers
2019-09-04 10:53 ` Oleg Nesterov
2019-09-04 11:39   ` Peter Zijlstra
2019-09-04 15:24   ` Mathieu Desnoyers
2019-09-04 11:11 ` Oleg Nesterov
2019-09-04 16:11   ` Mathieu Desnoyers
2019-09-08 13:46   ` Mathieu Desnoyers [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=509773035.243.1567950364367.JavaMail.zimbra@efficios.com \
    --to=mathieu.desnoyers@efficios.com \
    --cc=cl@linux.com \
    --cc=cmetcalf@ezchip.com \
    --cc=ebiederm@xmission.com \
    --cc=efault@gmx.de \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux@armlinux.org.uk \
    --cc=mingo@kernel.org \
    --cc=oleg@redhat.com \
    --cc=paulmck@linux.ibm.com \
    --cc=peterz@infradead.org \
    --cc=tglx@linutronix.de \
    --cc=tkhai@yandex.ru \
    --cc=torvalds@linux-foundation.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.