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Message-ID: <4FF291EE.7060408@linux.vnet.ibm.com> Date: Tue, 03 Jul 2012 14:32:14 +0800 From: Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com> To: Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com> CC: Avi Kivity <avi@...hat.com>, Marcelo Tosatti <mtosatti@...hat.com>, LKML <linux-kernel@...r.kernel.org>, KVM <kvm@...r.kernel.org> Subject: [PATCH 3/3] KVM: MMU: track the refcount when unmap the page 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))); + if (!shadow_accessed_mask || old_spte & shadow_accessed_mask) kvm_set_pfn_accessed(pfn); if (!shadow_dirty_mask || (old_spte & shadow_dirty_mask)) -- 1.7.7.6 -- 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/
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