[PATCH] MIPS/mm: add compound tail page _mapcount when mapped

[Jovi Zhang <bookjovi@gmail.com>]

>From 3dc19ea2b535719d0b4177f17bbbff9cbf257b23 Mon Sep 17 00:00:00 2001
From: Jovi Zhang <bookjovi@gmail.com>
Date: Wed, 22 Aug 2012 10:34:08 +0800
Subject: [PATCH] MIPS/mm: add compound tail page _mapcount when mapped

see commit b6999b191 which target for x86 mm/gup, let it align with
mips architecture.

Quote from commit b6999b191:
    "If compound pages are used and the page is a
    tail page, gup_huge_pmd() increases _mapcount to record tail page are
    mapped while gup_huge_pud does not do that."

Signed-off-by: Jovi Zhang <boojovi@gmail.com>
Cc: Youquan Song <youquan.song@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: <stable@vger.kernel.org>
---
 arch/mips/mm/gup.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/mips/mm/gup.c b/arch/mips/mm/gup.c
index 33aadbc..dcfd573 100644
--- a/arch/mips/mm/gup.c
+++ b/arch/mips/mm/gup.c
@@ -152,6 +152,8 @@ static int gup_huge_pud(pud_t pud, unsigned long
addr, unsigned long end,
        do {
                VM_BUG_ON(compound_head(page) != head);
                pages[*nr] = page;
+               if (PageTail(page))
+                       get_huge_page_tail(page);
                (*nr)++;
                page++;
                refs++;
-- 
1.7.9.7