From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: kvm: RCU warning in async pf
Date: Thu, 05 Apr 2012 19:10:55 +0300
Message-ID: <4F7DC40F.5000805@redhat.com>
References: <1333414472.11455.7.camel@lappy> <20120403105226.GF14939@redhat.com> <20120404123033.GD11918@redhat.com>
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Cc: Sasha Levin <levinsasha928@gmail.com>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@elte.hu>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	kvm <kvm@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Dave Jones <davej@redhat.com>
To: Gleb Natapov <gleb@redhat.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <20120404123033.GD11918@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
List-Id: kvm.vger.kernel.org

On 04/04/2012 03:30 PM, Gleb Natapov wrote:
> On Tue, Apr 03, 2012 at 01:52:26PM +0300, Gleb Natapov wrote:
> > On Mon, Apr 02, 2012 at 08:54:32PM -0400, Sasha Levin wrote:
> > > Hi all,
> > > 
> > > I got the spew at the bottom of the mail in a KVM guest using the KVM tools and running trinity.
> > > 
> > > I'm not quite sure how default_idle managed to trigger a pagefault, so that part looks odd to me.
> > > 
> > This is not regular page fault. This is async page fault that tells the
> > guest that a page, previously swapped out by hypervisor, is now swapped
> > back in and it can happen while vcpu is idle. The code does not leave
> > idle state properly though. We probably need to call rcu_irq_enter()
> > there. Will look into it.
> > 
>
> The patch below solves it for me:
>
> "Page ready" async PF can kick vcpu out of idle state much like IRQ.
> We need to tell RCU about this.
>
>

Applied it, thanks.

-- 
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