linux-kernel - Re: [PATCH 3/3] KVM: MMU: track the refcount when unmap the page

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20120703203053.GA13581@amt.cnet>
Date:	Tue, 3 Jul 2012 17:30:53 -0300
From:	Marcelo Tosatti <mtosatti@...hat.com>
To:	Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
Cc:	Avi Kivity <avi@...hat.com>, LKML <linux-kernel@...r.kernel.org>,
	KVM <kvm@...r.kernel.org>
Subject: Re: [PATCH 3/3] KVM: MMU: track the refcount when unmap the page

On Tue, Jul 03, 2012 at 02:32:14PM +0800, Xiao Guangrong wrote:
> It will trigger a WARN_ON if the page has been freed but it is still
> used in mmu, it can help us to detect mm bug early
> 
> Signed-off-by: Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
> ---
>  arch/x86/kvm/mmu.c |    8 ++++++++
>  1 files changed, 8 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index cac3408..af7e076 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -527,6 +527,14 @@ static int mmu_spte_clear_track_bits(u64 *sptep)
>  		return 0;
> 
>  	pfn = spte_to_pfn(old_spte);
> +
> +	/*
> +	 * KVM does not hold the refcount of the page used by
> +	 * kvm mmu, before reclaiming the page, we should
> +	 * unmap it from mmu first.
> +	 */
> +	WARN_ON(!page_count(pfn_to_page(pfn)));
> +

Except for mmio pfns.

Applied patch 1 and 2 to master, thanks.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/