[PATCH 3/9] mm: introduce api for split page table lock for PMD level

["Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>]

Basic api, backed by mm->page_table_lock for now. Actual implementation
will be added later.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 include/linux/mm.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 6cf8ddb..d4361e7 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1294,6 +1294,19 @@ static inline void pgtable_page_dtor(struct page *page)
 	((unlikely(pmd_none(*(pmd))) && __pte_alloc_kernel(pmd, address))? \
 		NULL: pte_offset_kernel(pmd, address))
 
+static inline spinlock_t *huge_pmd_lockptr(struct mm_struct *mm, pmd_t *pmd)
+{
+	return &mm->page_table_lock;
+}
+
+
+static inline spinlock_t *huge_pmd_lock(struct mm_struct *mm, pmd_t *pmd)
+{
+	spinlock_t *ptl = huge_pmd_lockptr(mm, pmd);
+	spin_lock(ptl);
+	return ptl;
+}
+
 extern void free_area_init(unsigned long * zones_size);
 extern void free_area_init_node(int nid, unsigned long * zones_size,
 		unsigned long zone_start_pfn, unsigned long *zholes_size);
-- 
1.8.4.rc3

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