7 files changed, 44 insertions, 12 deletions

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/cgroup_freezer.c b/kernel/cgroup_freezer.c
index da5e13975531..e5c0244962b0 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -205,9 +205,12 @@ static void freezer_fork(struct cgroup_subsys *ss, struct task_struct *task)
          * No lock is needed, since the task isn't on tasklist yet,
          * so it can't be moved to another cgroup, which means the
          * freezer won't be removed and will be valid during this
-         * function call.
+         * function call.  Nevertheless, apply RCU read-side critical
+         * section to suppress RCU lockdep false positives.
          */
+        rcu_read_lock();
         freezer = task_freezer(task);
+        rcu_read_unlock();
 
         /*
          * The root cgroup is non-freezable, so we can skip the
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 2f3fbf84215a..3d1552d3c12b 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -4897,7 +4897,7 @@ err_fput_free_put_context:
 
 err_free_put_context:
         if (err < 0)
-                kfree(event);
+                free_event(event);
 
 err_put_context:
         if (err < 0)
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.c b/kernel/sched.c
index 6af210a7de70..3c2a54f70ffe 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -323,6 +323,15 @@ static inline struct task_group *task_group(struct task_struct *p)
 /* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
 static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
 {
+        /*
+         * Strictly speaking this rcu_read_lock() is not needed since the
+         * task_group is tied to the cgroup, which in turn can never go away
+         * as long as there are tasks attached to it.
+         *
+         * However since task_group() uses task_subsys_state() which is an
+         * rcu_dereference() user, this quiets CONFIG_PROVE_RCU.
+         */
+        rcu_read_lock();
 #ifdef CONFIG_FAIR_GROUP_SCHED
         p->se.cfs_rq = task_group(p)->cfs_rq[cpu];
         p->se.parent = task_group(p)->se[cpu];
@@ -332,6 +341,7 @@ static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
         p->rt.rt_rq  = task_group(p)->rt_rq[cpu];
         p->rt.parent = task_group(p)->rt_se[cpu];
 #endif
+        rcu_read_unlock();
 }
 
 #else
@@ -3780,7 +3790,7 @@ int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner)
          * the mutex owner just released it and exited.
          */
         if (probe_kernel_address(&owner->cpu, cpu))
-                goto out;
+                return 0;
 #else
         cpu = owner->cpu;
 #endif
@@ -3790,14 +3800,14 @@ int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner)
          * the cpu field may no longer be valid.
          */
         if (cpu >= nr_cpumask_bits)
-                goto out;
+                return 0;
 
         /*
          * We need to validate that we can do a
          * get_cpu() and that we have the percpu area.
          */
         if (!cpu_online(cpu))
-                goto out;
+                return 0;
 
         rq = cpu_rq(cpu);
 
@@ -3816,7 +3826,7 @@ int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner)
 
                 cpu_relax();
         }
-out:
+
         return 1;
 }
 #endif
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/kernel/workqueue.c b/kernel/workqueue.c
index dee48658805c..5bfb213984b2 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -774,7 +774,7 @@ void flush_delayed_work(struct delayed_work *dwork)
 {
         if (del_timer_sync(&dwork->timer)) {
                 struct cpu_workqueue_struct *cwq;
-                cwq = wq_per_cpu(keventd_wq, get_cpu());
+                cwq = wq_per_cpu(get_wq_data(&dwork->work)->wq, get_cpu());
                 __queue_work(cwq, &dwork->work);
                 put_cpu();
         }