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From: Huang Ying on 22 Jun 2010 02:30
is_hwpoison_address accesses the page table, so the caller must hold
current->mm->mmap_sem in read mode. So fix its usage in hav_to_pfn of
kvm accordingly.

Comments on is_hwpoison_address are added to remind other users.

Reported-by: Avi Kivity <avi(a)redhat.com>
Signed-off-by: Huang Ying <ying.huang(a)intel.com>
---
mm/memory-failure.c | 3 +++
virt/kvm/kvm_main.c | 3 ++-
2 files changed, 5 insertions(+), 1 deletion(-)

--- 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;
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -955,12 +955,13 @@ static pfn_t hva_to_pfn(struct kvm *kvm,
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 ||


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Prev: [PATCH] Simplify conditional processing of fs/proc.o.
Next: Cleancache: overview