1 files changed, 30 insertions, 14 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 0ad946974df4..64f8aadb0595 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1288,18 +1288,18 @@ 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 anon_vma *anon_vma = NULL;
         struct page *page;
         unsigned long haddr = addr & HPAGE_PMD_MASK;
         int target_nid;
         int current_nid = -1;
-        bool migrated;
+        bool migrated, page_locked;
 
         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())
@@ -1309,12 +1309,29 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
          * Acquire the page lock to serialise THP migrations but avoid dropping
          * page_table_lock if at all possible
          */
-        if (trylock_page(page))
-                goto got_lock;
+        page_locked = trylock_page(page);
+        target_nid = mpol_misplaced(page, vma, haddr);
+        if (target_nid == -1) {
+                /* If the page was locked, there are no parallel migrations */
+                if (page_locked) {
+                        unlock_page(page);
+                        goto clear_pmdnuma;
+                }
 
-        /* Serialise against migrationa and check placement check placement */
+                /* Otherwise wait for potential migrations and retry fault */
+                spin_unlock(&mm->page_table_lock);
+                wait_on_page_locked(page);
+                goto out;
+        }
+
+        /* Page is misplaced, serialise migrations and parallel THP splits */
+        get_page(page);
         spin_unlock(&mm->page_table_lock);
-        lock_page(page);
+        if (!page_locked) {
+                lock_page(page);
+                page_locked = true;
+        }
+        anon_vma = page_lock_anon_vma_read(page);
 
         /* Confirm the PTE did not while locked */
         spin_lock(&mm->page_table_lock);
@@ -1324,14 +1341,6 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
                 goto out_unlock;
         }
 
-got_lock:
-        target_nid = mpol_misplaced(page, vma, haddr);
-        if (target_nid == -1) {
-                unlock_page(page);
-                put_page(page);
-                goto clear_pmdnuma;
-        }
-
         /* Migrate the THP to the requested node */
         spin_unlock(&mm->page_table_lock);
         migrated = migrate_misplaced_transhuge_page(mm, vma,
@@ -1340,6 +1349,8 @@ got_lock:
                 goto check_same;
 
         task_numa_fault(target_nid, HPAGE_PMD_NR, true);
+        if (anon_vma)
+                page_unlock_anon_vma_read(anon_vma);
         return 0;
 
 check_same:
@@ -1356,6 +1367,11 @@ clear_pmdnuma:
         update_mmu_cache_pmd(vma, addr, pmdp);
 out_unlock:
         spin_unlock(&mm->page_table_lock);
+
+out:
+        if (anon_vma)
+                page_unlock_anon_vma_read(anon_vma);
+
         if (current_nid != -1)
                 task_numa_fault(current_nid, HPAGE_PMD_NR, false);
         return 0;