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Date: Mon, 30 Sep 2013 17:06:53 +0200
From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [RFC] introduce synchronize_sched_{enter,exit}()
Message-ID: <20130930150653.GL26785@twins.programming.kicks-ass.net>
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To: Oleg Nesterov <oleg@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>, Rik van Riel <riel@redhat.com>, Srikar Dronamraju <srikar@linux.vnet.ibm.com>, Ingo Molnar <mingo@kernel.org>, Andrea Arcangeli <aarcange@redhat.com>, Johannes Weiner <hannes@cmpxchg.org>, Linux-MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>, Paul McKenney <paulmck@linux.vnet.ibm.com>, Thomas Gleixner <tglx@linutronix.de>, Steven Rostedt <rostedt@goodmis.org>, Linus Torvalds <torvalds@linux-foundation.org>

On Mon, Sep 30, 2013 at 04:24:00PM +0200, Peter Zijlstra wrote:
> For that we'd have to decrement xxx->gp_count from cb_rcu_func(),
> wouldn't we?
> 
> Without that there's no guarantee the fast path readers will have a MB
> to observe the write critical section, unless I'm completely missing
> something obviuos here.

Duh.. we should be looking at gp_state like Paul said.

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