[PATCH V2 06/12] MIPS: Ensure pmd_present() returns false after pmd_mknotpresent()

[Huacai Chen <chenhc@lemote.com>]

This patch is borrowed from ARM64 to ensure pmd_present() returns false
after pmd_mknotpresent(). This is needed for THP.

Cc: <stable@vger.kernel.org> # 3.8+
References: 5bb1cc0ff9a6 ("arm64: Ensure pmd_present() returns false after pmd_mknotpresent()")
Reviewed-by: James Hogan <jhogan@kernel.org>
Signed-off-by: Huacai Chen <chenhc@lemote.com>
---
 arch/mips/include/asm/pgtable-64.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/mips/include/asm/pgtable-64.h b/arch/mips/include/asm/pgtable-64.h
index 0036ea0..93a9dce 100644
--- a/arch/mips/include/asm/pgtable-64.h
+++ b/arch/mips/include/asm/pgtable-64.h
@@ -265,6 +265,11 @@ static inline int pmd_bad(pmd_t pmd)
 
 static inline int pmd_present(pmd_t pmd)
 {
+#ifdef CONFIG_MIPS_HUGE_TLB_SUPPORT
+	if (unlikely(pmd_val(pmd) & _PAGE_HUGE))
+		return pmd_val(pmd) & _PAGE_PRESENT;
+#endif
+
 	return pmd_val(pmd) != (unsigned long) invalid_pte_table;
 }
 
-- 
2.7.0