Merge branch 'akpm' (patches from Andrew)

Merge misc fixes from Andrew Morton:
 "4 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm, page_alloc: fix has_unmovable_pages for HugePages
  fork,memcg: fix crash in free_thread_stack on memcg charge fail
  mm: thp: fix flags for pmd migration when split
  mm, memory_hotplug: initialize struct pages for the full memory section

kernel/fork.c

@@ -240,8 +240,10 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
 	 * free_thread_stack() can be called in interrupt context,
 	 * so cache the vm_struct.
 	 */
-	if (stack)
+	if (stack) {
 		tsk->stack_vm_area = find_vm_area(stack);
+		tsk->stack = stack;
+	}
 	return stack;
 #else
 	struct page *page = alloc_pages_node(node, THREADINFO_GFP,
@@ -288,7 +290,10 @@ static struct kmem_cache *thread_stack_cache;
 static unsigned long *alloc_thread_stack_node(struct task_struct *tsk,
 						  int node)
 {
-	return kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
+	unsigned long *stack;
+	stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
+	tsk->stack = stack;
+	return stack;
 }
 
 static void free_thread_stack(struct task_struct *tsk)

mm/huge_memory.c

@@ -2144,23 +2144,25 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
 	 */
 	old_pmd = pmdp_invalidate(vma, haddr, pmd);
 
-#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
 	pmd_migration = is_pmd_migration_entry(old_pmd);
-	if (pmd_migration) {
+	if (unlikely(pmd_migration)) {
 		swp_entry_t entry;
 
 		entry = pmd_to_swp_entry(old_pmd);
 		page = pfn_to_page(swp_offset(entry));
-	} else
-#endif
+		write = is_write_migration_entry(entry);
+		young = false;
+		soft_dirty = pmd_swp_soft_dirty(old_pmd);
+	} else {
 		page = pmd_page(old_pmd);
-	VM_BUG_ON_PAGE(!page_count(page), page);
-	page_ref_add(page, HPAGE_PMD_NR - 1);
 		if (pmd_dirty(old_pmd))
 			SetPageDirty(page);
 		write = pmd_write(old_pmd);
 		young = pmd_young(old_pmd);
 		soft_dirty = pmd_soft_dirty(old_pmd);
+	}
+	VM_BUG_ON_PAGE(!page_count(page), page);
+	page_ref_add(page, HPAGE_PMD_NR - 1);
 
 	/*
 	 * Withdraw the table only after we mark the pmd entry invalid.

mm/page_alloc.c

@@ -5542,6 +5542,18 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
 			cond_resched();
 		}
 	}
+#ifdef CONFIG_SPARSEMEM
+	/*
+	 * If the zone does not span the rest of the section then
+	 * we should at least initialize those pages. Otherwise we
+	 * could blow up on a poisoned page in some paths which depend
+	 * on full sections being initialized (e.g. memory hotplug).
+	 */
+	while (end_pfn % PAGES_PER_SECTION) {
+		__init_single_page(pfn_to_page(end_pfn), end_pfn, zone, nid);
+		end_pfn++;
+	}
+#endif
 }
 
 #ifdef CONFIG_ZONE_DEVICE
@@ -7802,11 +7814,14 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
 		 * handle each tail page individually in migration.
 		 */
 		if (PageHuge(page)) {
+			struct page *head = compound_head(page);
+			unsigned int skip_pages;
 
-			if (!hugepage_migration_supported(page_hstate(page)))
+			if (!hugepage_migration_supported(page_hstate(head)))
 				goto unmovable;
 
-			iter = round_up(iter + 1, 1<<compound_order(page)) - 1;
+			skip_pages = (1 << compound_order(head)) - (page - head);
+			iter += skip_pages - 1;
 			continue;
 		}