diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
index 6571f82..fe68a5a 100644
--- a/include/linux/crash_dump.h
+++ b/include/linux/crash_dump.h
@@ -17,6 +17,9 @@
 extern void __weak elfcorehdr_free(unsigned long long addr);
 extern ssize_t __weak elfcorehdr_read(char *buf, size_t count, u64 *ppos);
 extern ssize_t __weak elfcorehdr_read_notes(char *buf, size_t count, u64 *ppos);
+extern int __weak remap_oldmem_pfn_range(struct vm_area_struct *vma,
+					 unsigned long from, unsigned long pfn,
+					 unsigned long size, pgprot_t prot);
 
 extern ssize_t copy_oldmem_page(unsigned long, char *, size_t,
 						unsigned long, int);