mm: numa: Add THP migration for the NUMA working set scanning fault case.

[platform/adaptation/renesas_rcar/renesas_kernel.git] / mm / huge_memory.c

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 199b261..711baf8 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -600,7 +600,7 @@ out:
 }
 __setup("transparent_hugepage=", setup_transparent_hugepage);
 
-static inline pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
+pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
 {
        if (likely(vma->vm_flags & VM_WRITE))
                pmd = pmd_mkwrite(pmd);
@@ -1023,10 +1023,12 @@ out:
 int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
                                unsigned long addr, pmd_t pmd, pmd_t *pmdp)
 {
-       struct page *page = NULL;
+       struct page *page;
        unsigned long haddr = addr & HPAGE_PMD_MASK;
        int target_nid;
        int current_nid = -1;
+       bool migrated;
+       bool page_locked = false;
 
        spin_lock(&mm->page_table_lock);
        if (unlikely(!pmd_same(pmd, *pmdp)))
@@ -1034,42 +1036,61 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
 
        page = pmd_page(pmd);
        get_page(page);
-       spin_unlock(&mm->page_table_lock);
        current_nid = page_to_nid(page);
        count_vm_numa_event(NUMA_HINT_FAULTS);
        if (current_nid == numa_node_id())
                count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
 
        target_nid = mpol_misplaced(page, vma, haddr);
-       if (target_nid == -1)
+       if (target_nid == -1) {
+               put_page(page);
                goto clear_pmdnuma;
+       }
 
-       /*
-        * Due to lacking code to migrate thp pages, we'll split
-        * (which preserves the special PROT_NONE) and re-take the
-        * fault on the normal pages.
-        */
-       split_huge_page(page);
-       put_page(page);
-
-       return 0;
+       /* Acquire the page lock to serialise THP migrations */
+       spin_unlock(&mm->page_table_lock);
+       lock_page(page);
+       page_locked = true;
 
-clear_pmdnuma:
+       /* Confirm the PTE did not while locked */
        spin_lock(&mm->page_table_lock);
-       if (unlikely(!pmd_same(pmd, *pmdp)))
+       if (unlikely(!pmd_same(pmd, *pmdp))) {
+               unlock_page(page);
+               put_page(page);
                goto out_unlock;
+       }
+       spin_unlock(&mm->page_table_lock);
+
+       /* Migrate the THP to the requested node */
+       migrated = migrate_misplaced_transhuge_page(mm, vma,
+                               pmdp, pmd, addr,
+                               page, target_nid);
+       if (migrated)
+               current_nid = target_nid;
+       else {
+               spin_lock(&mm->page_table_lock);
+               if (unlikely(!pmd_same(pmd, *pmdp))) {
+                       unlock_page(page);
+                       goto out_unlock;
+               }
+               goto clear_pmdnuma;
+       }
+
+       task_numa_fault(current_nid, HPAGE_PMD_NR, migrated);
+       return 0;
 
+clear_pmdnuma:
        pmd = pmd_mknonnuma(pmd);
        set_pmd_at(mm, haddr, pmdp, pmd);
        VM_BUG_ON(pmd_numa(*pmdp));
        update_mmu_cache_pmd(vma, addr, pmdp);
+       if (page_locked)
+               unlock_page(page);
 
 out_unlock:
        spin_unlock(&mm->page_table_lock);
-       if (page) {
-               put_page(page);
-               task_numa_fault(numa_node_id(), HPAGE_PMD_NR, false);
-       }
+       if (current_nid != -1)
+               task_numa_fault(current_nid, HPAGE_PMD_NR, migrated);
        return 0;
 }