1 files changed, 15 insertions, 6 deletions

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 753afbca549f..ef4242e5d4bc 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -488,7 +488,7 @@ static struct cgroup_subsys_state *cgroup_tryget_css(struct cgroup *cgrp,
 
 	rcu_read_lock();
 	css = cgroup_css(cgrp, ss);
-	if (!css || !css_tryget_online(css))
+	if (css && !css_tryget_online(css))
 		css = NULL;
 	rcu_read_unlock();
 
@@ -1891,7 +1891,7 @@ static int cgroup_reconfigure(struct fs_context *fc)
  */
 static bool use_task_css_set_links __read_mostly;
 
-static void cgroup_enable_task_cg_lists(void)
+void cgroup_enable_task_cg_lists(void)
 {
 	struct task_struct *p, *g;
 
@@ -2119,11 +2119,12 @@ int cgroup_do_get_tree(struct fs_context *fc)
 
 		nsdentry = kernfs_node_dentry(cgrp->kn, sb);
 		dput(fc->root);
-		fc->root = nsdentry;
 		if (IS_ERR(nsdentry)) {
-			ret = PTR_ERR(nsdentry);
 			deactivate_locked_super(sb);
+			ret = PTR_ERR(nsdentry);
+			nsdentry = NULL;
 		}
+		fc->root = nsdentry;
 	}
 
 	if (!ctx->kfc.new_sb_created)
@@ -2894,7 +2895,7 @@ static void cgroup_print_ss_mask(struct seq_file *seq, u16 ss_mask)
 	do_each_subsys_mask(ss, ssid, ss_mask) {
 		if (printed)
 			seq_putc(seq, ' ');
-		seq_printf(seq, "%s", ss->name);
+		seq_puts(seq, ss->name);
 		printed = true;
 	} while_each_subsys_mask();
 	if (printed)
@@ -5255,8 +5256,16 @@ static struct cgroup *cgroup_create(struct cgroup *parent)
 	 * if the parent has to be frozen, the child has too.
 	 */
 	cgrp->freezer.e_freeze = parent->freezer.e_freeze;
-	if (cgrp->freezer.e_freeze)
+	if (cgrp->freezer.e_freeze) {
+		/*
+		 * Set the CGRP_FREEZE flag, so when a process will be
+		 * attached to the child cgroup, it will become frozen.
+		 * At this point the new cgroup is unpopulated, so we can
+		 * consider it frozen immediately.
+		 */
+		set_bit(CGRP_FREEZE, &cgrp->flags);
 		set_bit(CGRP_FROZEN, &cgrp->flags);
+	}
 
 	spin_lock_irq(&css_set_lock);
 	for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp)) {