4 files changed, 43 insertions, 3 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 861cad53b744..255750d9b1be 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1378,13 +1378,45 @@ static inline void pgtable_page_dtor(struct page *page)
         ((unlikely(pmd_none(*(pmd))) && __pte_alloc_kernel(pmd, address))? \
                 NULL: pte_offset_kernel(pmd, address))
 
+#if USE_SPLIT_PMD_PTLOCKS
+
+static inline spinlock_t *pmd_lockptr(struct mm_struct *mm, pmd_t *pmd)
+{
+        return &virt_to_page(pmd)->ptl;
+}
+
+static inline bool pgtable_pmd_page_ctor(struct page *page)
+{
+        spin_lock_init(&page->ptl);
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+        page->pmd_huge_pte = NULL;
+#endif
+        return true;
+}
+
+static inline void pgtable_pmd_page_dtor(struct page *page)
+{
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+        VM_BUG_ON(page->pmd_huge_pte);
+#endif
+}
+
+#define pmd_huge_pte(mm, pmd) (virt_to_page(pmd)->pmd_huge_pte)
+
+#else
+
 static inline spinlock_t *pmd_lockptr(struct mm_struct *mm, pmd_t *pmd)
 {
         return &mm->page_table_lock;
 }
 
+static inline bool pgtable_pmd_page_ctor(struct page *page) { return true; }
+static inline void pgtable_pmd_page_dtor(struct page *page) {}
+
 #define pmd_huge_pte(mm, pmd) ((mm)->pmd_huge_pte)
 
+#endif
+
 static inline spinlock_t *pmd_lock(struct mm_struct *mm, pmd_t *pmd)
 {
         spinlock_t *ptl = pmd_lockptr(mm, pmd);
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 566df579c51f..934261099975 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -24,6 +24,8 @@
 struct address_space;
 
 #define USE_SPLIT_PTE_PTLOCKS   (NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS)
+#define USE_SPLIT_PMD_PTLOCKS   (USE_SPLIT_PTE_PTLOCKS && \
+                IS_ENABLED(CONFIG_ARCH_ENABLE_SPLIT_PMD_PTLOCK))
 
 /*
  * Each physical page in the system has a struct page associated with
@@ -63,6 +65,9 @@ struct page {
                                                  * this page is only used to
                                                  * free other pages.
                                                  */
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && USE_SPLIT_PMD_PTLOCKS
+                pgtable_t pmd_huge_pte; /* protected by page->ptl */
+#endif
                 };
 
                 union {
@@ -406,7 +411,7 @@ struct mm_struct {
 #ifdef CONFIG_MMU_NOTIFIER
         struct mmu_notifier_mm *mmu_notifier_mm;
 #endif
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
         pgtable_t pmd_huge_pte; /* protected by page_table_lock */
 #endif
 #ifdef CONFIG_CPUMASK_OFFSTACK
diff --git a/kernel/fork.c b/kernel/fork.c
index e2520756e005..728d5be9548c 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -560,7 +560,7 @@ static void check_mm(struct mm_struct *mm)
                                           "mm:%p idx:%d val:%ld\n", mm, i, x);
         }
 
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
         VM_BUG_ON(mm->pmd_huge_pte);
 #endif
 }
@@ -814,7 +814,7 @@ struct mm_struct *dup_mm(struct task_struct *tsk)
         memcpy(mm, oldmm, sizeof(*mm));
         mm_init_cpumask(mm);
 
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
         mm->pmd_huge_pte = NULL;
 #endif
         if (!mm_init(mm, tsk))
diff --git a/mm/Kconfig b/mm/Kconfig
index c28d247e524a..7aa02def4666 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -222,6 +222,9 @@ config SPLIT_PTLOCK_CPUS
         default "999999" if !64BIT && GENERIC_LOCKBREAK
         default "4"
 
+config ARCH_ENABLE_SPLIT_PMD_PTLOCK
+        boolean
+
 #
 # support for memory balloon compaction
 config BALLOON_COMPACTION