From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paul Mackerras <paulus@samba.org>
Subject: Re: [PATCH 21/23] KVM: PPC: Book3S PR: Use mmu_notifier_retry() in
 kvmppc_mmu_map_page()
Date: Wed, 7 Aug 2013 14:28:50 +1000
Message-ID: <20130807042850.GE31007@iris.ozlabs.ibm.com>
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 <20130806042732.GA19254@iris.ozlabs.ibm.com>
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Cc: Alexander Graf <agraf@suse.de>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	"kvm-ppc@vger.kernel.org" <kvm-ppc@vger.kernel.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>
To: Bhushan Bharat-R65777 <R65777@freescale.com>
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On Wed, Aug 07, 2013 at 04:13:34AM +0000, Bhushan Bharat-R65777 wrote:
> 
> > +	/* used to check for invalidations in progress */
> > +	mmu_seq = kvm->mmu_notifier_seq;
> > +	smp_rmb();
> 
> Should not the smp_rmb() come before reading kvm->mmu_notifier_seq.

No, it should come after, because it is ordering the read of
kvm->mmu_notifier_seq before the read of the Linux PTE.

Paul.