Merge branch 'akpm' (patches from Andrew)

Merge misc fixes from Andrew Morton:
 "19 patches.

  Subsystems affected by this patch series: mm (userfaultfd, migration,
  memblock, mempolicy, slub, secretmem, and thp), ocfs2, binfmt, vfs,
  and misc"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mailmap: add Andrej Shadura
  mm/thp: decrease nr_thps in file's mapping on THP split
  mm/secretmem: fix NULL page->mapping dereference in page_is_secretmem()
  vfs: check fd has read access in kernel_read_file_from_fd()
  elfcore: correct reference to CONFIG_UML
  mm, slub: fix incorrect memcg slab count for bulk free
  mm, slub: fix potential use-after-free in slab_debugfs_fops
  mm, slub: fix potential memoryleak in kmem_cache_open()
  mm, slub: fix mismatch between reconstructed freelist depth and cnt
  mm, slub: fix two bugs in slab_debug_trace_open()
  mm/mempolicy: do not allow illegal MPOL_F_NUMA_BALANCING | MPOL_LOCAL in mbind()
  memblock: check memory total_size
  ocfs2: mount fails with buffer overflow in strlen
  ocfs2: fix data corruption after conversion from inline format
  mm/migrate: fix CPUHP state to update node demotion order
  mm/migrate: add CPU hotplug to demotion #ifdef
  mm/migrate: optimize hotplug-time demotion order updates
  userfaultfd: fix a race between writeprotect and exit_mmap()
  mm/userfaultfd: selftests: fix memory corruption with thp enabled

1 files changed, 37 insertions, 25 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index a6a7743ee98f..1852d787e6ab 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -3066,7 +3066,7 @@ void migrate_vma_finalize(struct migrate_vma *migrate)
 EXPORT_SYMBOL(migrate_vma_finalize);
 #endif /* CONFIG_DEVICE_PRIVATE */
 
-#if defined(CONFIG_MEMORY_HOTPLUG)
+#if defined(CONFIG_HOTPLUG_CPU)
 /* Disable reclaim-based migration. */
 static void __disable_all_migrate_targets(void)
 {
@@ -3209,25 +3209,6 @@ static void set_migration_target_nodes(void)
 }
 
 /*
- * React to hotplug events that might affect the migration targets
- * like events that online or offline NUMA nodes.
- *
- * The ordering is also currently dependent on which nodes have
- * CPUs.  That means we need CPU on/offline notification too.
- */
-static int migration_online_cpu(unsigned int cpu)
-{
-	set_migration_target_nodes();
-	return 0;
-}
-
-static int migration_offline_cpu(unsigned int cpu)
-{
-	set_migration_target_nodes();
-	return 0;
-}
-
-/*
  * This leaves migrate-on-reclaim transiently disabled between
  * the MEM_GOING_OFFLINE and MEM_OFFLINE events.  This runs
  * whether reclaim-based migration is enabled or not, which
@@ -3239,8 +3220,18 @@ static int migration_offline_cpu(unsigned int cpu)
  * set_migration_target_nodes().
  */
 static int __meminit migrate_on_reclaim_callback(struct notifier_block *self,
-						 unsigned long action, void *arg)
+						 unsigned long action, void *_arg)
 {
+	struct memory_notify *arg = _arg;
+
+	/*
+	 * Only update the node migration order when a node is
+	 * changing status, like online->offline.  This avoids
+	 * the overhead of synchronize_rcu() in most cases.
+	 */
+	if (arg->status_change_nid < 0)
+		return notifier_from_errno(0);
+
 	switch (action) {
 	case MEM_GOING_OFFLINE:
 		/*
@@ -3274,13 +3265,31 @@ static int __meminit migrate_on_reclaim_callback(struct notifier_block *self,
 	return notifier_from_errno(0);
 }
 
+/*
+ * React to hotplug events that might affect the migration targets
+ * like events that online or offline NUMA nodes.
+ *
+ * The ordering is also currently dependent on which nodes have
+ * CPUs.  That means we need CPU on/offline notification too.
+ */
+static int migration_online_cpu(unsigned int cpu)
+{
+	set_migration_target_nodes();
+	return 0;
+}
+
+static int migration_offline_cpu(unsigned int cpu)
+{
+	set_migration_target_nodes();
+	return 0;
+}
+
 static int __init migrate_on_reclaim_init(void)
 {
 	int ret;
 
-	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "migrate on reclaim",
-				migration_online_cpu,
-				migration_offline_cpu);
+	ret = cpuhp_setup_state_nocalls(CPUHP_MM_DEMOTION_DEAD, "mm/demotion:offline",
+					NULL, migration_offline_cpu);
 	/*
 	 * In the unlikely case that this fails, the automatic
 	 * migration targets may become suboptimal for nodes
@@ -3288,9 +3297,12 @@ static int __init migrate_on_reclaim_init(void)
 	 * rare case, do not bother trying to do anything special.
 	 */
 	WARN_ON(ret < 0);
+	ret = cpuhp_setup_state(CPUHP_AP_MM_DEMOTION_ONLINE, "mm/demotion:online",
+				migration_online_cpu, NULL);
+	WARN_ON(ret < 0);
 
 	hotplug_memory_notifier(migrate_on_reclaim_callback, 100);
 	return 0;
 }
 late_initcall(migrate_on_reclaim_init);
-#endif /* CONFIG_MEMORY_HOTPLUG */
+#endif /* CONFIG_HOTPLUG_CPU */