mm: add MAP_HUGETLB for mmaping pseudo-anonymous huge page regions

Add a flag for mmap that will be used to request a huge page region that
will look like anonymous memory to user space.  This is accomplished by
using a file on the internal vfsmount.  MAP_HUGETLB is a modifier of
MAP_ANONYMOUS and so must be specified with it.  The region will behave
the same as a MAP_ANONYMOUS region using small pages.

The patch also adds the MAP_STACK flag, which was previously defined only
on some architectures but not on others.  Since MAP_STACK is meant to be a
hint only, architectures can define it without assigning a specific
meaning to it.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Eric B Munson <ebmunson@us.ibm.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: David Rientjes <rientjes@google.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/asm-generic/mman.h b/include/asm-generic/mman.h
index 7cab4de2bca6..32c8bd6a196d 100644
--- a/include/asm-generic/mman.h
+++ b/include/asm-generic/mman.h
@@ -11,6 +11,7 @@
 #define MAP_POPULATE    0x8000          /* populate (prefault) pagetables */
 #define MAP_NONBLOCK    0x10000         /* do not block on IO */
 #define MAP_STACK       0x20000         /* give out an address that is best suited for process/thread stacks */
+#define MAP_HUGETLB     0x40000         /* create a huge page mapping */
 
 #define MCL_CURRENT     1               /* lock all current mappings */
 #define MCL_FUTURE      2               /* lock all future mappings */