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, 2 insertions, 0 deletions

diff --git a/arch/alpha/include/asm/mman.h b/arch/alpha/include/asm/mman.h
index c77c55756a7c..99c56d47879d 100644
--- a/arch/alpha/include/asm/mman.h
+++ b/arch/alpha/include/asm/mman.h
@@ -28,6 +28,8 @@
 #define MAP_NORESERVE   0x10000         /* don't check for reservations */
 #define MAP_POPULATE    0x20000         /* populate (prefault) pagetables */
 #define MAP_NONBLOCK    0x40000         /* do not block on IO */
+#define MAP_STACK       0x80000         /* give out an address that is best suited for process/thread stacks */
+#define MAP_HUGETLB     0x100000        /* create a huge page mapping */
 
 #define MS_ASYNC        1               /* sync memory asynchronously */
 #define MS_SYNC         2               /* synchronous memory sync */