mm/follow_page_mask: add support for hugepage directory entry
authorAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Thu, 6 Jul 2017 22:38:56 +0000 (15:38 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 6 Jul 2017 23:24:33 +0000 (16:24 -0700)
commit4dc71451a2078efcad2f66bd6ef130d2296827b1
tree42f0896ed2bc9e7e59a4943b1b50fde56fb73a6a
parente22992923f741c951b830121655b58342fce202e
mm/follow_page_mask: add support for hugepage directory entry

Architectures like ppc64 supports hugepage size that is not mapped to
any of of the page table levels.  Instead they add an alternate page
table entry format called hugepage directory (hugepd).  hugepd indicates
that the page table entry maps to a set of hugetlb pages.  Add support
for this in generic follow_page_mask code.  We already support this
format in the generic gup code.

The default implementation prints warning and returns NULL.  We will add
ppc64 support in later patches

Link: http://lkml.kernel.org/r/1494926612-23928-7-git-send-email-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Mike Kravetz <kravetz@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/hugetlb.h
mm/gup.c
mm/hugetlb.c