From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrea Arcangeli <andrea@qumranet.com>
Subject: Re: madvise() not triggering page discard with MMU-notifiers
Date: Thu, 28 Aug 2008 16:23:56 +0200
Message-ID: <20080828142356.GA19754@duo.random>
References: <48A9F1E9.6040907@us.ibm.com>
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Cc: Avi Kivity <avi@qumranet.com>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	kvm-devel <kvm@vger.kernel.org>
To: Anthony Liguori <aliguori@us.ibm.com>
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On Mon, Aug 18, 2008 at 05:04:25PM -0500, Anthony Liguori wrote:
> +    if (!kvm_enabled() || !qemu_kvm_has_mmu_notifiers())
> +        madvise(addr, TARGET_PAGE_SIZE,
> +                deflate ? MADV_WILLNEED : MADV_DONTNEED);

The check was reversed so madvise wasn't invoked in the first place if
mmu notifier was enabled in the host kernel. This should fix it
(untested):

       if (!kvm_enabled() || kvm_has_sync_mmu())