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

[Jovi Zhang]

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@xxxxxxxxx>
Cc: Youquan Song <youquan.song@xxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
---
 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
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