[PATCH 3.16 005/305] x86/mm: Fix regression with huge pages on PAE

[Ben Hutchings <ben@decadent.org.uk>]

3.16.63-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>

commit 70f1528747651b20c7769d3516ade369f9963237 upstream.

Recent PAT patchset has caused issue on 32-bit PAE machines:

  page:eea45000 count:0 mapcount:-128 mapping:  (null) index:0x0 flags: 0x40000000()
  page dumped because: VM_BUG_ON_PAGE(page_mapcount(page) < 0)
  ------------[ cut here ]------------
  kernel BUG at /home/build/linux-boris/mm/huge_memory.c:1485!
  invalid opcode: 0000 [#1] SMP
  [...]
  Call Trace:
   unmap_single_vma
   ? __wake_up
   unmap_vmas
   unmap_region
   do_munmap
   vm_munmap
   SyS_munmap
   do_fast_syscall_32
   ? __do_page_fault
   sysenter_past_esp
  Code: ...
  EIP: [<c11bde80>] zap_huge_pmd+0x240/0x260 SS:ESP 0068:f6459d98

The problem is in pmd_pfn_mask() and pmd_flags_mask(). These
helpers use PMD_PAGE_MASK to calculate resulting mask.
PMD_PAGE_MASK is 'unsigned long', not 'unsigned long long' as
phys_addr_t is on 32-bit PAE (ARCH_PHYS_ADDR_T_64BIT). As a
result, the upper bits of resulting mask get truncated.

pud_pfn_mask() and pud_flags_mask() aren't problematic since we
don't have PUD page table level on 32-bit systems, but it's
reasonable to keep them consistent with PMD counterpart.

Introduce PHYSICAL_PMD_PAGE_MASK and PHYSICAL_PUD_PAGE_MASK in
addition to existing PHYSICAL_PAGE_MASK and reworks helpers to
use them.

Reported-and-Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
[ Fix -Woverflow warnings from the realmode code. ]
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Toshi Kani <toshi.kani@hpe.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jürgen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: elliott@hpe.com
Cc: konrad.wilk@oracle.com
Cc: linux-mm <linux-mm@kvack.org>
Fixes: f70abb0fc3da ("x86/asm: Fix pud/pmd interfaces to handle large PAT bit")
Link: http://lkml.kernel.org/r/1448878233-11390-2-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 arch/x86/boot/boot.h                 |  1 -
 arch/x86/boot/video-mode.c           |  2 ++
 arch/x86/boot/video.c                |  2 ++
 arch/x86/include/asm/page_types.h    | 16 +++++++++-------
 arch/x86/include/asm/pgtable_types.h | 14 ++++----------
 arch/x86/include/asm/x86_init.h      |  1 -
 6 files changed, 17 insertions(+), 19 deletions(-)

--- a/arch/x86/boot/boot.h
+++ b/arch/x86/boot/boot.h
@@ -23,7 +23,6 @@
 #include <stdarg.h>
 #include <linux/types.h>
 #include <linux/edd.h>
-#include <asm/boot.h>
 #include <asm/setup.h>
 #include "bitops.h"
 #include "ctype.h"
--- a/arch/x86/boot/video-mode.c
+++ b/arch/x86/boot/video-mode.c
@@ -19,6 +19,8 @@
 #include "video.h"
 #include "vesa.h"
 
+#include <uapi/asm/boot.h>
+
 /*
  * Common variables
  */
--- a/arch/x86/boot/video.c
+++ b/arch/x86/boot/video.c
@@ -13,6 +13,8 @@
  * Select video mode
  */
 
+#include <uapi/asm/boot.h>
+
 #include "boot.h"
 #include "video.h"
 #include "vesa.h"
--- a/arch/x86/include/asm/page_types.h
+++ b/arch/x86/include/asm/page_types.h
@@ -9,19 +9,21 @@
 #define PAGE_SIZE	(_AC(1,UL) << PAGE_SHIFT)
 #define PAGE_MASK	(~(PAGE_SIZE-1))
 
+#define PMD_PAGE_SIZE		(_AC(1, UL) << PMD_SHIFT)
+#define PMD_PAGE_MASK		(~(PMD_PAGE_SIZE-1))
+
+#define PUD_PAGE_SIZE		(_AC(1, UL) << PUD_SHIFT)
+#define PUD_PAGE_MASK		(~(PUD_PAGE_SIZE-1))
+
 #define __PHYSICAL_MASK		((phys_addr_t)((1ULL << __PHYSICAL_MASK_SHIFT) - 1))
 #define __VIRTUAL_MASK		((1UL << __VIRTUAL_MASK_SHIFT) - 1)
 
-/* Cast PAGE_MASK to a signed type so that it is sign-extended if
+/* Cast *PAGE_MASK to a signed type so that it is sign-extended if
    virtual addresses are 32-bits but physical addresses are larger
    (ie, 32-bit PAE). */
 #define PHYSICAL_PAGE_MASK	(((signed long)PAGE_MASK) & __PHYSICAL_MASK)
-
-#define PMD_PAGE_SIZE		(_AC(1, UL) << PMD_SHIFT)
-#define PMD_PAGE_MASK		(~(PMD_PAGE_SIZE-1))
-
-#define PUD_PAGE_SIZE		(_AC(1, UL) << PUD_SHIFT)
-#define PUD_PAGE_MASK		(~(PUD_PAGE_SIZE-1))
+#define PHYSICAL_PMD_PAGE_MASK	(((signed long)PMD_PAGE_MASK) & __PHYSICAL_MASK)
+#define PHYSICAL_PUD_PAGE_MASK	(((signed long)PUD_PAGE_MASK) & __PHYSICAL_MASK)
 
 #define HPAGE_SHIFT		PMD_SHIFT
 #define HPAGE_SIZE		(_AC(1,UL) << HPAGE_SHIFT)
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -332,17 +332,14 @@ static inline pmdval_t native_pmd_val(pm
 static inline pudval_t pud_pfn_mask(pud_t pud)
 {
 	if (native_pud_val(pud) & _PAGE_PSE)
-		return PUD_PAGE_MASK & PHYSICAL_PAGE_MASK;
+		return PHYSICAL_PUD_PAGE_MASK;
 	else
 		return PTE_PFN_MASK;
 }
 
 static inline pudval_t pud_flags_mask(pud_t pud)
 {
-	if (native_pud_val(pud) & _PAGE_PSE)
-		return ~(PUD_PAGE_MASK & (pudval_t)PHYSICAL_PAGE_MASK);
-	else
-		return ~PTE_PFN_MASK;
+	return ~pud_pfn_mask(pud);
 }
 
 static inline pudval_t pud_flags(pud_t pud)
@@ -353,17 +350,14 @@ static inline pudval_t pud_flags(pud_t p
 static inline pmdval_t pmd_pfn_mask(pmd_t pmd)
 {
 	if (native_pmd_val(pmd) & _PAGE_PSE)
-		return PMD_PAGE_MASK & PHYSICAL_PAGE_MASK;
+		return PHYSICAL_PMD_PAGE_MASK;
 	else
 		return PTE_PFN_MASK;
 }
 
 static inline pmdval_t pmd_flags_mask(pmd_t pmd)
 {
-	if (native_pmd_val(pmd) & _PAGE_PSE)
-		return ~(PMD_PAGE_MASK & (pmdval_t)PHYSICAL_PAGE_MASK);
-	else
-		return ~PTE_PFN_MASK;
+	return ~pmd_pfn_mask(pmd);
 }
 
 static inline pmdval_t pmd_flags(pmd_t pmd)
--- a/arch/x86/include/asm/x86_init.h
+++ b/arch/x86/include/asm/x86_init.h
@@ -1,7 +1,6 @@
 #ifndef _ASM_X86_PLATFORM_H
 #define _ASM_X86_PLATFORM_H
 
-#include <asm/pgtable_types.h>
 #include <asm/bootparam.h>
 
 struct mpc_bus;