[PATCH] mm: correct _PAGE_FILE comment
_PAGE_FILE does not indicate whether a file is in page / swap cache, it is
set just for non-linear PTE's. Correct the comment for i386, x86_64, UML.
Also clearify _PAGE_NONE.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/asm-i386/pgtable.h b/include/asm-i386/pgtable.h
index 77c6497f..c797286 100644
--- a/include/asm-i386/pgtable.h
+++ b/include/asm-i386/pgtable.h
@@ -86,9 +86,7 @@
#endif
/*
- * The 4MB page is guessing.. Detailed in the infamous "Chapter H"
- * of the Pentium details, but assuming intel did the straightforward
- * thing, this bit set in the page directory entry just means that
+ * _PAGE_PSE set in the page directory entry just means that
* the page directory entry points directly to a 4MB-aligned block of
* memory.
*/
@@ -119,8 +117,10 @@
#define _PAGE_UNUSED2 0x400
#define _PAGE_UNUSED3 0x800
-#define _PAGE_FILE 0x040 /* set:pagecache unset:swap */
-#define _PAGE_PROTNONE 0x080 /* If not present */
+/* If _PAGE_PRESENT is clear, we use these: */
+#define _PAGE_FILE 0x040 /* nonlinear file mapping, saved PTE; unset:swap */
+#define _PAGE_PROTNONE 0x080 /* if the user mapped it with PROT_NONE;
+ pte_present gives true */
#ifdef CONFIG_X86_PAE
#define _PAGE_NX (1ULL<<_PAGE_BIT_NX)
#else
diff --git a/include/asm-um/pgtable.h b/include/asm-um/pgtable.h
index a880409..e9336f6 100644
--- a/include/asm-um/pgtable.h
+++ b/include/asm-um/pgtable.h
@@ -16,13 +16,15 @@
#define _PAGE_PRESENT 0x001
#define _PAGE_NEWPAGE 0x002
-#define _PAGE_NEWPROT 0x004
-#define _PAGE_FILE 0x008 /* set:pagecache unset:swap */
-#define _PAGE_PROTNONE 0x010 /* If not present */
+#define _PAGE_NEWPROT 0x004
#define _PAGE_RW 0x020
#define _PAGE_USER 0x040
#define _PAGE_ACCESSED 0x080
#define _PAGE_DIRTY 0x100
+/* If _PAGE_PRESENT is clear, we use these: */
+#define _PAGE_FILE 0x008 /* nonlinear file mapping, saved PTE; unset:swap */
+#define _PAGE_PROTNONE 0x010 /* if the user mapped it with PROT_NONE;
+ pte_present gives true */
#ifdef CONFIG_3_LEVEL_PGTABLES
#include "asm/pgtable-3level.h"
diff --git a/include/asm-x86_64/pgtable.h b/include/asm-x86_64/pgtable.h
index 4e167b5..20476d1 100644
--- a/include/asm-x86_64/pgtable.h
+++ b/include/asm-x86_64/pgtable.h
@@ -143,7 +143,7 @@
#define _PAGE_ACCESSED 0x020
#define _PAGE_DIRTY 0x040
#define _PAGE_PSE 0x080 /* 2MB page */
-#define _PAGE_FILE 0x040 /* set:pagecache, unset:swap */
+#define _PAGE_FILE 0x040 /* nonlinear file mapping, saved PTE; unset:swap */
#define _PAGE_GLOBAL 0x100 /* Global TLB entry */
#define _PAGE_PROTNONE 0x080 /* If not present */