From bbeb34062fbad287c949a945a516a0c15b179993 Mon Sep 17 00:00:00 2001 From: Huang Ying Date: Tue, 22 Jun 2010 14:23:11 +0800 Subject: KVM: Fix a race condition for usage of is_hwpoison_address() is_hwpoison_address accesses the page table, so the caller must hold current->mm->mmap_sem in read mode. So fix its usage in hva_to_pfn of kvm accordingly. Comment is_hwpoison_address to remind other users. Reported-by: Avi Kivity Signed-off-by: Huang Ying Signed-off-by: Avi Kivity --- mm/memory-failure.c | 3 +++ virt/kvm/kvm_main.c | 3 ++- 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 378b0f61fd3c..6b44e52cacaa 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1298,6 +1298,9 @@ done: return ret; } +/* + * The caller must hold current->mm->mmap_sem in read mode. + */ int is_hwpoison_address(unsigned long addr) { pgd_t *pgdp; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 74f731920945..ec2e3c6ac7ed 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -947,12 +947,13 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr) if (unlikely(npages != 1)) { struct vm_area_struct *vma; + down_read(¤t->mm->mmap_sem); if (is_hwpoison_address(addr)) { + up_read(¤t->mm->mmap_sem); get_page(hwpoison_page); return page_to_pfn(hwpoison_page); } - down_read(¤t->mm->mmap_sem); vma = find_vma(current->mm, addr); if (vma == NULL || addr < vma->vm_start || -- cgit v1.2.3