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From: Thomas Gleixner <tglx@linutronix.de>
To: Davidlohr Bueso <dave@stgolabs.net>
Cc: Mel Gorman <mgorman@techsingularity.net>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Chris Mason <clm@fb.com>, Darren Hart <dvhart@linux.intel.com>,
	Hugh Dickins <hughd@google.com>,
	linux-kernel@vger.kernel.org, Davidlohr Bueso <dbueso@suse.de>,
	Mel Gorman <mgorman@suse.de>
Subject: Re: [PATCH v5] futex: Remove requirement for lock_page in get_futex_key
Date: Thu, 4 Feb 2016 10:06:11 +0100 (CET)	[thread overview]
Message-ID: <alpine.DEB.2.11.1602041002010.25254@nanos> (raw)
In-Reply-To: <1454567326-16114-1-git-send-email-dave@stgolabs.net>

On Wed, 3 Feb 2016, Davidlohr Bueso wrote:
> +		 * We are not calling into get_futex_key_refs() in file-backed
> +		 * cases, therefore a successful atomic_inc return below will
> +		 * guarantee that get_futex_key() will continue to imply MB (B).

Can you please make that "MB (B)" part a bit more outstanding. I really had to
search for it.

> +		 */
> +		if (WARN_ON_ONCE(!atomic_inc_not_zero(&inode->i_count))) {
> +			rcu_read_unlock();
> +			put_page(page);
> +
> +			goto again;
> +		}

Don't we need 

		smp_mb__after_atomic();

here to make it a full barrier on all architectures?

Thanks,

	tglx

  reply	other threads:[~2016-02-04  9:07 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-04  6:28 [PATCH v5] futex: Remove requirement for lock_page in get_futex_key Davidlohr Bueso
2016-02-04  9:06 ` Thomas Gleixner [this message]
2016-02-04 17:43   ` Davidlohr Bueso
2016-02-04 17:50     ` Thomas Gleixner
2016-02-05  9:44       ` Ingo Molnar
2016-02-05 18:02         ` Davidlohr Bueso
2016-02-06  8:22           ` Ingo Molnar

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