linux-kernel - [PATCH 3.16 11/99] MIPS: Ensure pmd_present() returns false after pmd

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Date:   Tue, 02 Apr 2019 14:38:27 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Paul Burton" <paul.burton@...s.com>,
        "James Hogan" <james.hogan@...s.com>,
        "Zhangjin Wu" <wuzhangjin@...il.com>,
        "Fuxin Zhang" <zhangfx@...ote.com>, linux-mips@...ux-mips.org,
        "Steven J . Hill" <Steven.Hill@...ium.com>,
        "Ralf Baechle" <ralf@...ux-mips.org>,
        "James Hogan" <jhogan@...nel.org>,
        "Huacai Chen" <chenhc@...ote.com>
Subject: [PATCH 3.16 11/99] MIPS: Ensure pmd_present() returns false after
 pmd_mknotpresent()

3.16.65-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Huacai Chen <chenhc@...ote.com>

commit 92aa0718c9fa5160ad2f0e7b5bffb52f1ea1e51a upstream.

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

References: 5bb1cc0ff9a6 ("arm64: Ensure pmd_present() returns false after pmd_mknotpresent()")
Reviewed-by: James Hogan <jhogan@...nel.org>
Signed-off-by: Huacai Chen <chenhc@...ote.com>
Signed-off-by: Paul Burton <paul.burton@...s.com>
Patchwork: https://patchwork.linux-mips.org/patch/21135/
Cc: Ralf Baechle <ralf@...ux-mips.org>
Cc: James Hogan <james.hogan@...s.com>
Cc: Steven J . Hill <Steven.Hill@...ium.com>
Cc: linux-mips@...ux-mips.org
Cc: Fuxin Zhang <zhangfx@...ote.com>
Cc: Zhangjin Wu <wuzhangjin@...il.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/mips/include/asm/pgtable-64.h | 5 +++++
 1 file changed, 5 insertions(+)

--- a/arch/mips/include/asm/pgtable-64.h
+++ b/arch/mips/include/asm/pgtable-64.h
@@ -189,6 +189,11 @@ 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;
 }