MIPS: mm: Add compound tail page _mapcount when mapped

See commit b6999b191 which did the same modification for x86's mm/gup,

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."

[ralf@linux-mips.org: fixed rejects caused by the original patch getting
linewrapped.]

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>
Patchwork: https://patchwork.linux-mips.org/patch/4291/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/mm/gup.c b/arch/mips/mm/gup.c
index 33aadbcf170bb4428020ddb87a17383180719400..dcfd573871c142348c4fa790bfcbd3dcc0c50879 100644 (file)
--- 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++;