diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 455f3fe..356ed2d 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -915,15 +915,15 @@
 
 void vmalloc_sync_all(void)
 {
-#ifdef CONFIG_X86_32
-	unsigned long start = VMALLOC_START & PGDIR_MASK;
 	unsigned long address;
 
+#ifdef CONFIG_X86_32
 	if (SHARED_KERNEL_PMD)
 		return;
 
-	BUILD_BUG_ON(TASK_SIZE & ~PGDIR_MASK);
-	for (address = start; address >= TASK_SIZE; address += PGDIR_SIZE) {
+	for (address = VMALLOC_START & PMD_MASK;
+	     address >= TASK_SIZE && address < FIXADDR_TOP;
+	     address += PMD_SIZE) {
 		unsigned long flags;
 		struct page *page;
 
@@ -936,10 +936,8 @@
 		spin_unlock_irqrestore(&pgd_lock, flags);
 	}
 #else /* CONFIG_X86_64 */
-	unsigned long start = VMALLOC_START & PGDIR_MASK;
-	unsigned long address;
-
-	for (address = start; address <= VMALLOC_END; address += PGDIR_SIZE) {
+	for (address = VMALLOC_START & PGDIR_MASK; address <= VMALLOC_END;
+	     address += PGDIR_SIZE) {
 		const pgd_t *pgd_ref = pgd_offset_k(address);
 		unsigned long flags;
 		struct page *page;