From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: KVM: mmu_notifiers release method Date: Wed, 10 Dec 2008 21:23:26 +0100 Message-ID: <20081210202326.GA7565@dmt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm-devel To: Andrea Arcangeli Return-path: Received: from mx2.redhat.com ([66.187.237.31]:59364 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754541AbYLJXZ3 (ORCPT ); Wed, 10 Dec 2008 18:25:29 -0500 Received: from int-mx2.corp.redhat.com (int-mx2.corp.redhat.com [172.16.27.26]) by mx2.redhat.com (8.13.8/8.13.8) with ESMTP id mBANPS8M012561 for ; Wed, 10 Dec 2008 18:25:28 -0500 Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-ID: The destructor for huge pages uses the backing inode for adjusting hugetlbfs accounting. Hugepage mappings are destroyed by exit_mmap, after mmu_notifier_release, so there are no notifications through unmap_hugepage_range at this point. The hugetlbfs inode can be freed with pages backed by it referenced by the shadow. When the shadow releases its reference, the huge page destructor will access a now freed inode. Implement the release operation for kvm mmu notifiers to release page refs before the hugetlbfs inode is gone. Signed-off-by: Marcelo Tosatti diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index e7644b9..5bc38b5 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -741,11 +741,19 @@ static int kvm_mmu_notifier_clear_flush_young(struct mmu_notifier *mn, return young; } +static void kvm_mmu_notifier_release(struct mmu_notifier *mn, + struct mm_struct *mm) +{ + struct kvm *kvm = mmu_notifier_to_kvm(mn); + kvm_arch_flush_shadow(kvm); +} + static const struct mmu_notifier_ops kvm_mmu_notifier_ops = { .invalidate_page = kvm_mmu_notifier_invalidate_page, .invalidate_range_start = kvm_mmu_notifier_invalidate_range_start, .invalidate_range_end = kvm_mmu_notifier_invalidate_range_end, .clear_flush_young = kvm_mmu_notifier_clear_flush_young, + .release = kvm_mmu_notifier_release, }; #endif /* CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER */