diff --git a/mm/memory.c b/mm/memory.c
index 0721395..4ad2d29 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1537,10 +1537,15 @@ static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
 			 * in may not match the PFN we have mapped if the
 			 * mapped PFN is a writeable COW page.  In the mkwrite
 			 * case we are creating a writable PTE for a shared
-			 * mapping and we expect the PFNs to match.
+			 * mapping and we expect the PFNs to match. If they
+			 * don't match, we are likely racing with block
+			 * allocation and mapping invalidation so just skip the
+			 * update.
 			 */
-			if (WARN_ON_ONCE(pte_pfn(*pte) != pfn_t_to_pfn(pfn)))
+			if (pte_pfn(*pte) != pfn_t_to_pfn(pfn)) {
+				WARN_ON_ONCE(!is_zero_pfn(pte_pfn(*pte)));
 				goto out_unlock;
+			}
 			entry = *pte;
 			goto out_mkwrite;
 		} else