[PATCHv5 11/11] x86, mm: enable split page table lock for PMD level

[Kirill A. Shutemov]

Enable PMD split page table lock for X86_64 and PAE.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Tested-by: Alex Thorlton <athorlton@xxxxxxx>
---
 arch/x86/Kconfig               |  4 ++++
 arch/x86/include/asm/pgalloc.h | 11 ++++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ee2fb9d377..015d1362b7 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1880,6 +1880,10 @@ config USE_PERCPU_NUMA_NODE_ID
 	def_bool y
 	depends on NUMA
 
+config ARCH_ENABLE_SPLIT_PMD_PTLOCK
+	def_bool y
+	depends on X86_64 || X86_PAE
+
 menu "Power management and ACPI options"
 
 config ARCH_HIBERNATION_HEADER
diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h
index b4389a468f..e2fb2b6934 100644
--- a/arch/x86/include/asm/pgalloc.h
+++ b/arch/x86/include/asm/pgalloc.h
@@ -80,12 +80,21 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
 #if PAGETABLE_LEVELS > 2
 static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
 {
-	return (pmd_t *)get_zeroed_page(GFP_KERNEL|__GFP_REPEAT);
+	struct page *page;
+	page = alloc_pages(GFP_KERNEL | __GFP_REPEAT| __GFP_ZERO, 0);
+	if (!page)
+		return NULL;
+	if (!pgtable_pmd_page_ctor(page)) {
+		__free_pages(page, 0);
+		return NULL;
+	}
+	return (pmd_t *)page_address(page);
 }
 
 static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
 {
 	BUG_ON((unsigned long)pmd & (PAGE_SIZE-1));
+	pgtable_pmd_page_dtor(virt_to_page(pmd));
 	free_page((unsigned long)pmd);
 }
 
-- 
1.8.4.rc3

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