6 files changed, 43 insertions, 10 deletions

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index b8ad1ea99586..8f78073d7caa 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -530,6 +530,7 @@ static inline struct cgroup_subsys_state *task_subsys_state(
 {
         return rcu_dereference_check(task->cgroups->subsys[subsys_id],
                                      rcu_read_lock_held() ||
+                                     lockdep_is_held(&task->alloc_lock) ||
                                      cgroup_lock_is_held());
 }
 
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 07db2feb8572..db266bbed23f 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -190,6 +190,8 @@ static inline int rcu_read_lock_sched_held(void)
 
 #ifdef CONFIG_PROVE_RCU
 
+extern int rcu_my_thread_group_empty(void);
+
 /**
  * rcu_dereference_check - rcu_dereference with debug checking
  * @p: The pointer to read, prior to dereferencing
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index e2769e13980c..3a53c771e503 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1646,7 +1646,9 @@ static inline struct cftype *__d_cft(struct dentry *dentry)
 int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen)
 {
         char *start;
-        struct dentry *dentry = rcu_dereference(cgrp->dentry);
+        struct dentry *dentry = rcu_dereference_check(cgrp->dentry,
+                                                      rcu_read_lock_held() ||
+                                                      cgroup_lock_is_held());
 
         if (!dentry || cgrp == dummytop) {
                 /*
@@ -1662,13 +1664,17 @@ int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen)
         *--start = '\0';
         for (;;) {
                 int len = dentry->d_name.len;
+
                 if ((start -= len) < buf)
                         return -ENAMETOOLONG;
-                memcpy(start, cgrp->dentry->d_name.name, len);
+                memcpy(start, dentry->d_name.name, len);
                 cgrp = cgrp->parent;
                 if (!cgrp)
                         break;
-                dentry = rcu_dereference(cgrp->dentry);
+
+                dentry = rcu_dereference_check(cgrp->dentry,
+                                               rcu_read_lock_held() ||
+                                               cgroup_lock_is_held());
                 if (!cgrp->parent)
                         continue;
                 if (--start < buf)
@@ -4555,13 +4561,13 @@ static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent,
 {
         int subsys_id, i, depth = 0;
         struct cgroup_subsys_state *parent_css, *child_css;
-        struct css_id *child_id, *parent_id = NULL;
+        struct css_id *child_id, *parent_id;
 
         subsys_id = ss->subsys_id;
         parent_css = parent->subsys[subsys_id];
         child_css = child->subsys[subsys_id];
-        depth = css_depth(parent_css) + 1;
         parent_id = parent_css->id;
+        depth = parent_id->depth;
 
         child_id = get_new_cssid(ss, depth);
         if (IS_ERR(child_id))
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index 03a7ea1579f6..49d808e833b0 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -122,3 +122,14 @@ void wakeme_after_rcu(struct rcu_head  *head)
         rcu = container_of(head, struct rcu_synchronize, head);
         complete(&rcu->completion);
 }
+
+#ifdef CONFIG_PROVE_RCU
+/*
+ * wrapper function to avoid #include problems.
+ */
+int rcu_my_thread_group_empty(void)
+{
+        return thread_group_empty(current);
+}
+EXPORT_SYMBOL_GPL(rcu_my_thread_group_empty);
+#endif /* #ifdef CONFIG_PROVE_RCU */
diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c
index 9b49db144037..19be00ba6123 100644
--- a/kernel/sched_debug.c
+++ b/kernel/sched_debug.c
@@ -114,7 +114,9 @@ print_task(struct seq_file *m, struct rq *rq, struct task_struct *p)
         {
                 char path[64];
 
+                rcu_read_lock();
                 cgroup_path(task_group(p)->css.cgroup, path, sizeof(path));
+                rcu_read_unlock();
                 SEQ_printf(m, " %s", path);
         }
 #endif
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6c755de385f7..0f711c213d2e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -811,10 +811,12 @@ int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem)
          * enabled in "curr" and "curr" is a child of "mem" in *cgroup*
          * hierarchy(even if use_hierarchy is disabled in "mem").
          */
+        rcu_read_lock();
         if (mem->use_hierarchy)
                 ret = css_is_ancestor(&curr->css, &mem->css);
         else
                 ret = (curr == mem);
+        rcu_read_unlock();
         css_put(&curr->css);
         return ret;
 }
@@ -2312,7 +2314,9 @@ mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
 
         /* record memcg information */
         if (do_swap_account && swapout && memcg) {
+                rcu_read_lock();
                 swap_cgroup_record(ent, css_id(&memcg->css));
+                rcu_read_unlock();
                 mem_cgroup_get(memcg);
         }
         if (swapout && memcg)
@@ -2369,8 +2373,10 @@ static int mem_cgroup_move_swap_account(swp_entry_t entry,
 {
         unsigned short old_id, new_id;
 
+        rcu_read_lock();
         old_id = css_id(&from->css);
         new_id = css_id(&to->css);
+        rcu_read_unlock();
 
         if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
                 mem_cgroup_swap_statistics(from, false);
@@ -4038,11 +4044,16 @@ static int is_target_pte_for_mc(struct vm_area_struct *vma,
                         put_page(page);
         }
         /* throught */
-        if (ent.val && do_swap_account && !ret &&
-                        css_id(&mc.from->css) == lookup_swap_cgroup(ent)) {
-                ret = MC_TARGET_SWAP;
-                if (target)
-                        target->ent = ent;
+        if (ent.val && do_swap_account && !ret) {
+                unsigned short id;
+                rcu_read_lock();
+                id = css_id(&mc.from->css);
+                rcu_read_unlock();
+                if (id == lookup_swap_cgroup(ent)) {
+                        ret = MC_TARGET_SWAP;
+                        if (target)
+                                target->ent = ent;
+                }
         }
         return ret;
 }