mm: introduce arch-specific vma flag VM_ARCH_1

Combine several arch-specific vma flags into one.

before patch:

        0x00000200      0x01000000      0x20000000      0x40000000
x86     VM_NOHUGEPAGE   VM_HUGEPAGE     -               VM_PAT
powerpc -               -               VM_SAO          -
parisc  VM_GROWSUP      -               -               -
ia64    VM_GROWSUP      -               -               -
nommu   -               VM_MAPPED_COPY  -               -
others  -               -               -               -

after patch:

        0x00000200      0x01000000      0x20000000      0x40000000
x86     -               VM_PAT          VM_HUGEPAGE     VM_NOHUGEPAGE
powerpc -               VM_SAO          -               -
parisc  -               VM_GROWSUP      -               -
ia64    -               VM_GROWSUP      -               -
nommu   -               VM_MAPPED_COPY  -               -
others  -               VM_ARCH_1       -               -

And voila! One completely free bit.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Carsten Otte <cotte@de.ibm.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Eric Paris <eparis@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Kentaro Takeda <takedakn@nttdata.co.jp>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Venkatesh Pallipadi <venki@google.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 28 insertions, 15 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 75d1632d3477..9c039f84b63c 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -70,6 +70,8 @@ extern unsigned int kobjsize(const void *objp);
 /*
  * vm_flags in vm_area_struct, see mm_types.h.
  */
+#define VM_NONE         0x00000000
+
 #define VM_READ         0x00000001      /* currently active flags */
 #define VM_WRITE        0x00000002
 #define VM_EXEC         0x00000004
@@ -82,12 +84,6 @@ extern unsigned int kobjsize(const void *objp);
 #define VM_MAYSHARE     0x00000080
 
 #define VM_GROWSDOWN    0x00000100      /* general info on the segment */
-#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
-#define VM_GROWSUP      0x00000200
-#else
-#define VM_GROWSUP      0x00000000
-#define VM_NOHUGEPAGE   0x00000200      /* MADV_NOHUGEPAGE marked this vma */
-#endif
 #define VM_PFNMAP       0x00000400      /* Page-ranges managed without "struct page", just pure PFN */
 #define VM_DENYWRITE    0x00000800      /* ETXTBSY on write attempts.. */
 
@@ -106,20 +102,32 @@ extern unsigned int kobjsize(const void *objp);
 #define VM_NORESERVE    0x00200000      /* should the VM suppress accounting */
 #define VM_HUGETLB      0x00400000      /* Huge TLB Page VM */
 #define VM_NONLINEAR    0x00800000      /* Is non-linear (remap_file_pages) */
-#ifndef CONFIG_TRANSPARENT_HUGEPAGE
-#define VM_MAPPED_COPY  0x01000000      /* T if mapped copy of data (nommu mmap) */
-#else
-#define VM_HUGEPAGE     0x01000000      /* MADV_HUGEPAGE marked this vma */
-#endif
+#define VM_ARCH_1       0x01000000      /* Architecture-specific flag */
 #define VM_INSERTPAGE   0x02000000      /* The vma has had "vm_insert_page()" done on it */
 #define VM_NODUMP       0x04000000      /* Do not include in the core dump */
 
 #define VM_CAN_NONLINEAR 0x08000000     /* Has ->fault & does nonlinear pages */
 #define VM_MIXEDMAP     0x10000000      /* Can contain "struct page" and pure PFN pages */
-#define VM_SAO          0x20000000      /* Strong Access Ordering (powerpc) */
-#define VM_PAT          0x40000000      /* PAT reserves whole VMA at once (x86) */
+#define VM_HUGEPAGE     0x20000000      /* MADV_HUGEPAGE marked this vma */
+#define VM_NOHUGEPAGE   0x40000000      /* MADV_NOHUGEPAGE marked this vma */
 #define VM_MERGEABLE    0x80000000      /* KSM may merge identical pages */
 
+#if defined(CONFIG_X86)
+# define VM_PAT         VM_ARCH_1       /* PAT reserves whole VMA at once (x86) */
+#elif defined(CONFIG_PPC)
+# define VM_SAO         VM_ARCH_1       /* Strong Access Ordering (powerpc) */
+#elif defined(CONFIG_PARISC)
+# define VM_GROWSUP     VM_ARCH_1
+#elif defined(CONFIG_IA64)
+# define VM_GROWSUP     VM_ARCH_1
+#elif !defined(CONFIG_MMU)
+# define VM_MAPPED_COPY VM_ARCH_1       /* T if mapped copy of data (nommu mmap) */
+#endif
+
+#ifndef VM_GROWSUP
+# define VM_GROWSUP     VM_NONE
+#endif
+
 /* Bits set in the VMA until the stack is in its final location */
 #define VM_STACK_INCOMPLETE_SETUP       (VM_RAND_READ | VM_SEQ_READ)
 
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 73cb22ee9665..47206692cf88 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1491,7 +1491,7 @@ out:
         return ret;
 }
 
-#define VM_NO_THP (VM_SPECIAL|VM_INSERTPAGE|VM_MIXEDMAP|VM_SAO| \
+#define VM_NO_THP (VM_SPECIAL|VM_INSERTPAGE|VM_MIXEDMAP| \
                    VM_HUGETLB|VM_SHARED|VM_MAYSHARE)
 
 int hugepage_madvise(struct vm_area_struct *vma,
diff --git a/mm/ksm.c b/mm/ksm.c
index 47c885368890..d1cbe2aa6b3a 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1470,9 +1470,14 @@ int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
                 if (*vm_flags & (VM_MERGEABLE | VM_SHARED  | VM_MAYSHARE   |
                                  VM_PFNMAP    | VM_IO      | VM_DONTEXPAND |
                                  VM_RESERVED  | VM_HUGETLB | VM_INSERTPAGE |
-                                 VM_NONLINEAR | VM_MIXEDMAP | VM_SAO))
+                                 VM_NONLINEAR | VM_MIXEDMAP))
                         return 0;               /* just ignore the advice */
 
+#ifdef VM_SAO
+                if (*vm_flags & VM_SAO)
+                        return 0;
+#endif
+
                 if (!test_bit(MMF_VM_MERGEABLE, &mm->flags)) {
                         err = __ksm_enter(mm);
                         if (err)