mm: add missing __PAGETABLE_{PUD,PMD}_FOLDED defines

Core mm expects __PAGETABLE_{PUD,PMD}_FOLDED to be defined if these page
table levels folded.  Usually, these defines are provided by
<asm-generic/pgtable-nopmd.h> and <asm-generic/pgtable-nopud.h>.

But some architectures fold page table levels in a custom way.  They
need to define these macros themself.  This patch adds missing defines.

The patch fixes mm->nr_pmds underflow and eliminates dead __pmd_alloc()
and __pud_alloc() on architectures without these page table levels.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: David Howells <dhowells@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/frv/include/asm/pgtable.h

@@ -123,12 +123,14 @@ extern unsigned long empty_zero_page;
 #define PGDIR_MASK		(~(PGDIR_SIZE - 1))
 #define PTRS_PER_PGD		64
 
+#define __PAGETABLE_PUD_FOLDED
 #define PUD_SHIFT		26
 #define PTRS_PER_PUD		1
 #define PUD_SIZE		(1UL << PUD_SHIFT)
 #define PUD_MASK		(~(PUD_SIZE - 1))
 #define PUE_SIZE		256
 
+#define __PAGETABLE_PMD_FOLDED
 #define PMD_SHIFT		26
 #define PMD_SIZE		(1UL << PMD_SHIFT)
 #define PMD_MASK		(~(PMD_SIZE - 1))

arch/m32r/include/asm/pgtable-2level.h

@@ -13,6 +13,7 @@
  * the M32R is two-level, so we don't really have any
  * PMD directory physically.
  */
+#define __PAGETABLE_PMD_FOLDED
 #define PMD_SHIFT	22
 #define PTRS_PER_PMD	1
 

arch/m68k/include/asm/pgtable_mm.h

@@ -54,10 +54,12 @@
  */
 #ifdef CONFIG_SUN3
 #define PTRS_PER_PTE   16
+#define __PAGETABLE_PMD_FOLDED
 #define PTRS_PER_PMD   1
 #define PTRS_PER_PGD   2048
 #elif defined(CONFIG_COLDFIRE)
 #define PTRS_PER_PTE	512
+#define __PAGETABLE_PMD_FOLDED
 #define PTRS_PER_PMD	1
 #define PTRS_PER_PGD	1024
 #else

arch/mn10300/include/asm/pgtable.h

@@ -56,7 +56,9 @@ extern void paging_init(void);
 #define PGDIR_SHIFT	22
 #define PTRS_PER_PGD	1024
 #define PTRS_PER_PUD	1	/* we don't really have any PUD physically */
+#define __PAGETABLE_PUD_FOLDED
 #define PTRS_PER_PMD	1	/* we don't really have any PMD physically */
+#define __PAGETABLE_PMD_FOLDED
 #define PTRS_PER_PTE	1024
 
 #define PGD_SIZE	PAGE_SIZE

arch/parisc/include/asm/pgtable.h

@@ -96,6 +96,7 @@ extern void purge_tlb_entries(struct mm_struct *, unsigned long);
 #if PT_NLEVELS == 3
 #define BITS_PER_PMD	(PAGE_SHIFT + PMD_ORDER - BITS_PER_PMD_ENTRY)
 #else
+#define __PAGETABLE_PMD_FOLDED
 #define BITS_PER_PMD	0
 #endif
 #define PTRS_PER_PMD    (1UL << BITS_PER_PMD)

arch/s390/include/asm/pgtable.h

@@ -91,7 +91,9 @@ extern unsigned long zero_page_mask;
  */
 #define PTRS_PER_PTE	256
 #ifndef CONFIG_64BIT
+#define __PAGETABLE_PUD_FOLDED
 #define PTRS_PER_PMD	1
+#define __PAGETABLE_PMD_FOLDED
 #define PTRS_PER_PUD	1
 #else /* CONFIG_64BIT */
 #define PTRS_PER_PMD	2048