+/* NUMA hinting page fault entry point for trans huge pmds */
+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;
+ 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)))
+ goto out_unlock;
+
+ page = pmd_page(pmd);
+ get_page(page);
+ 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) {
+ put_page(page);
+ goto clear_pmdnuma;
+ }
+
+ /* Acquire the page lock to serialise THP migrations */
+ spin_unlock(&mm->page_table_lock);
+ lock_page(page);
+ page_locked = true;
+
+ /* Confirm the PTE did not while locked */
+ spin_lock(&mm->page_table_lock);
+ 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 (current_nid != -1)
+ task_numa_fault(current_nid, HPAGE_PMD_NR, migrated);
+ return 0;
+}
+