diff --git a/arch/x86/include/asm/pgtable-2level.h b/arch/x86/include/asm/pgtable-2level.h
index b17edfd..e0d199f 100644
--- a/arch/x86/include/asm/pgtable-2level.h
+++ b/arch/x86/include/asm/pgtable-2level.h
@@ -56,23 +56,55 @@
 #define pte_none(x)		(!(x).pte_low)
 
 /*
- * Bits 0, 6 and 7 are taken, split up the 29 bits of offset
- * into this range:
+ * Bits _PAGE_BIT_PRESENT, _PAGE_BIT_FILE and _PAGE_BIT_PROTNONE are taken,
+ * split up the 29 bits of offset into this range:
  */
 #define PTE_FILE_MAX_BITS	29
+#define PTE_FILE_SHIFT1		(_PAGE_BIT_PRESENT + 1)
+#if _PAGE_BIT_FILE < _PAGE_BIT_PROTNONE
+#define PTE_FILE_SHIFT2		(_PAGE_BIT_FILE + 1)
+#define PTE_FILE_SHIFT3		(_PAGE_BIT_PROTNONE + 1)
+#else
+#define PTE_FILE_SHIFT2		(_PAGE_BIT_PROTNONE + 1)
+#define PTE_FILE_SHIFT3		(_PAGE_BIT_FILE + 1)
+#endif
+#define PTE_FILE_BITS1		(PTE_FILE_SHIFT2 - PTE_FILE_SHIFT1 - 1)
+#define PTE_FILE_BITS2		(PTE_FILE_SHIFT3 - PTE_FILE_SHIFT2 - 1)
 
 #define pte_to_pgoff(pte)						\
-	((((pte).pte_low >> 1) & 0x1f) + (((pte).pte_low >> 8) << 5))
+	((((pte).pte_low >> PTE_FILE_SHIFT1)				\
+	  & ((1U << PTE_FILE_BITS1) - 1))				\
+	 + ((((pte).pte_low >> PTE_FILE_SHIFT2)				\
+	     & ((1U << PTE_FILE_BITS2) - 1)) << PTE_FILE_BITS1)		\
+	 + (((pte).pte_low >> PTE_FILE_SHIFT3)				\
+	    << (PTE_FILE_BITS1 + PTE_FILE_BITS2)))
 
 #define pgoff_to_pte(off)						\
-	((pte_t) { .pte_low = (((off) & 0x1f) << 1) +			\
-			(((off) >> 5) << 8) + _PAGE_FILE })
+	((pte_t) { .pte_low =						\
+	 (((off) & ((1U << PTE_FILE_BITS1) - 1)) << PTE_FILE_SHIFT1)	\
+	 + ((((off) >> PTE_FILE_BITS1) & ((1U << PTE_FILE_BITS2) - 1))	\
+	    << PTE_FILE_SHIFT2)						\
+	 + (((off) >> (PTE_FILE_BITS1 + PTE_FILE_BITS2))		\
+	    << PTE_FILE_SHIFT3)						\
+	 + _PAGE_FILE })
 
 /* Encode and de-code a swap entry */
-#define __swp_type(x)			(((x).val >> 1) & 0x1f)
-#define __swp_offset(x)			((x).val >> 8)
-#define __swp_entry(type, offset)				\
-	((swp_entry_t) { ((type) << 1) | ((offset) << 8) })
+#if _PAGE_BIT_FILE < _PAGE_BIT_PROTNONE
+#define SWP_TYPE_BITS (_PAGE_BIT_FILE - _PAGE_BIT_PRESENT - 1)
+#define SWP_OFFSET_SHIFT (_PAGE_BIT_PROTNONE + 1)
+#else
+#define SWP_TYPE_BITS (_PAGE_BIT_PROTNONE - _PAGE_BIT_PRESENT - 1)
+#define SWP_OFFSET_SHIFT (_PAGE_BIT_FILE + 1)
+#endif
+
+#define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > SWP_TYPE_BITS)
+
+#define __swp_type(x)			(((x).val >> (_PAGE_BIT_PRESENT + 1)) \
+					 & ((1U << SWP_TYPE_BITS) - 1))
+#define __swp_offset(x)			((x).val >> SWP_OFFSET_SHIFT)
+#define __swp_entry(type, offset)	((swp_entry_t) { \
+					 ((type) << (_PAGE_BIT_PRESENT + 1)) \
+					 | ((offset) << SWP_OFFSET_SHIFT) })
 #define __pte_to_swp_entry(pte)		((swp_entry_t) { (pte).pte_low })
 #define __swp_entry_to_pte(x)		((pte_t) { .pte = (x).val })
 
diff --git a/arch/x86/include/asm/pgtable-3level.h b/arch/x86/include/asm/pgtable-3level.h
index 52597ae..447da43 100644
--- a/arch/x86/include/asm/pgtable-3level.h
+++ b/arch/x86/include/asm/pgtable-3level.h
@@ -166,6 +166,7 @@
 #define PTE_FILE_MAX_BITS       32
 
 /* Encode and de-code a swap entry */
+#define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > 5)
 #define __swp_type(x)			(((x).val) & 0x1f)
 #define __swp_offset(x)			((x).val >> 5)
 #define __swp_entry(type, offset)	((swp_entry_t){(type) | (offset) << 5})
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index c012f3b..b7c2ecd 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -10,7 +10,6 @@
 #define _PAGE_BIT_PCD		4	/* page cache disabled */
 #define _PAGE_BIT_ACCESSED	5	/* was accessed (raised by CPU) */
 #define _PAGE_BIT_DIRTY		6	/* was written to (raised by CPU) */
-#define _PAGE_BIT_FILE		6
 #define _PAGE_BIT_PSE		7	/* 4 MB (or 2MB) page */
 #define _PAGE_BIT_PAT		7	/* on 4KB pages */
 #define _PAGE_BIT_GLOBAL	8	/* Global TLB entry PPro+ */
@@ -22,6 +21,12 @@
 #define _PAGE_BIT_CPA_TEST	_PAGE_BIT_UNUSED1
 #define _PAGE_BIT_NX           63       /* No execute: only valid after cpuid check */
 
+/* If _PAGE_BIT_PRESENT is clear, we use these: */
+/* - if the user mapped it with PROT_NONE; pte_present gives true */
+#define _PAGE_BIT_PROTNONE	_PAGE_BIT_GLOBAL
+/* - set: nonlinear file mapping, saved PTE; unset:swap */
+#define _PAGE_BIT_FILE		_PAGE_BIT_DIRTY
+
 #define _PAGE_PRESENT	(_AT(pteval_t, 1) << _PAGE_BIT_PRESENT)
 #define _PAGE_RW	(_AT(pteval_t, 1) << _PAGE_BIT_RW)
 #define _PAGE_USER	(_AT(pteval_t, 1) << _PAGE_BIT_USER)
@@ -46,11 +51,8 @@
 #define _PAGE_NX	(_AT(pteval_t, 0))
 #endif
 
-/* If _PAGE_PRESENT is clear, we use these: */
-#define _PAGE_FILE	_PAGE_DIRTY	/* nonlinear file mapping,
-					 * saved PTE; unset:swap */
-#define _PAGE_PROTNONE	_PAGE_PSE	/* if the user mapped it with PROT_NONE;
-					   pte_present gives true */
+#define _PAGE_FILE	(_AT(pteval_t, 1) << _PAGE_BIT_FILE)
+#define _PAGE_PROTNONE	(_AT(pteval_t, 1) << _PAGE_BIT_PROTNONE)
 
 #define _PAGE_TABLE	(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER |	\
 			 _PAGE_ACCESSED | _PAGE_DIRTY)
diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index 545a0e0..65b6be6 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -250,10 +250,22 @@
 extern int direct_gbpages;
 
 /* Encode and de-code a swap entry */
-#define __swp_type(x)			(((x).val >> 1) & 0x3f)
-#define __swp_offset(x)			((x).val >> 8)
-#define __swp_entry(type, offset)	((swp_entry_t) { ((type) << 1) | \
-							 ((offset) << 8) })
+#if _PAGE_BIT_FILE < _PAGE_BIT_PROTNONE
+#define SWP_TYPE_BITS (_PAGE_BIT_FILE - _PAGE_BIT_PRESENT - 1)
+#define SWP_OFFSET_SHIFT (_PAGE_BIT_PROTNONE + 1)
+#else
+#define SWP_TYPE_BITS (_PAGE_BIT_PROTNONE - _PAGE_BIT_PRESENT - 1)
+#define SWP_OFFSET_SHIFT (_PAGE_BIT_FILE + 1)
+#endif
+
+#define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > SWP_TYPE_BITS)
+
+#define __swp_type(x)			(((x).val >> (_PAGE_BIT_PRESENT + 1)) \
+					 & ((1U << SWP_TYPE_BITS) - 1))
+#define __swp_offset(x)			((x).val >> SWP_OFFSET_SHIFT)
+#define __swp_entry(type, offset)	((swp_entry_t) { \
+					 ((type) << (_PAGE_BIT_PRESENT + 1)) \
+					 | ((offset) << SWP_OFFSET_SHIFT) })
 #define __pte_to_swp_entry(pte)		((swp_entry_t) { pte_val((pte)) })
 #define __swp_entry_to_pte(x)		((pte_t) { .pte = (x).val })
 
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 90cb67a..54a9f87 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1462,6 +1462,15 @@
 __initcall(procswaps_init);
 #endif /* CONFIG_PROC_FS */
 
+#ifdef MAX_SWAPFILES_CHECK
+static int __init max_swapfiles_check(void)
+{
+	MAX_SWAPFILES_CHECK();
+	return 0;
+}
+late_initcall(max_swapfiles_check);
+#endif
+
 /*
  * Written 01/25/92 by Simmule Turner, heavily changed by Linus.
  *