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Commit bbeb3406 authored Jun 22, 2010 by Huang Ying Committed by Avi Kivity Aug 01, 2010

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 <avi@redhat.com>
Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

parent 6c3f6041

mm/memory-failure.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -1298,6 +1298,9 @@ int soft_offline_page(struct page *page, int flags)
		return ret;
		}

		/*
		* The caller must hold current->mm->mmap_sem in read mode.
		*/
		int is_hwpoison_address(unsigned long addr)
		{
		pgd_t *pgdp;

virt/kvm/kvm_main.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -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(&current->mm->mmap_sem);
		if (is_hwpoison_address(addr)) {
		up_read(&current->mm->mmap_sem);
		get_page(hwpoison_page);
		return page_to_pfn(hwpoison_page);
		}

		down_read(&current->mm->mmap_sem);
		vma = find_vma(current->mm, addr);

		if (vma == NULL \|\| addr < vma->vm_start \|\|