KVM: MMU: handle compound pages in kvm_is_mmio_pfn

The function kvm_is_mmio_pfn is called before put_page is called on a page by KVM. This is a problem when when this function is called on some struct page which is part of a compund page. It does not test the reserved flag of the compound page but of the struct page within the compount page. This is a problem when KVM works with hugepages allocated at boot time. These pages have the reserved bit set in all tail pages. Only the flag in the compount head is cleared. KVM would not put such a page which results in a memory leak. Signed-off-by: Joerg Roedel <[email protected]> Acked-by: Marcelo Tosatti <[email protected]> Signed-off-by: Avi Kivity <[email protected]>
mna · Mar 24, 2009 · fc5659c · fc5659c
1 parent c807660
commit fc5659c
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
@@ -535,8 +535,10 @@ static inline int valid_vcpu(int n)
 
 inline int kvm_is_mmio_pfn(pfn_t pfn)
 {
-	if (pfn_valid(pfn))
-		return PageReserved(pfn_to_page(pfn));
+	if (pfn_valid(pfn)) {
+		struct page *page = compound_head(pfn_to_page(pfn));
+		return PageReserved(page);
+	}
 
 	return true;
 }