1 files changed, 20 insertions, 13 deletions

diff --git a/kernel/cpu.c b/kernel/cpu.c
index a343bde710b1..81e2a388a0f6 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -274,21 +274,28 @@ void clear_tasks_mm_cpumask(int cpu)
         rcu_read_unlock();
 }
 
-static inline void check_for_tasks(int cpu)
+static inline void check_for_tasks(int dead_cpu)
 {
-        struct task_struct *p;
-        cputime_t utime, stime;
+        struct task_struct *g, *p;
 
-        write_lock_irq(&tasklist_lock);
-        for_each_process(p) {
-                task_cputime(p, &utime, &stime);
-                if (task_cpu(p) == cpu && p->state == TASK_RUNNING &&
-                    (utime || stime))
-                        pr_warn("Task %s (pid = %d) is on cpu %d (state = %ld, flags = %x)\n",
-                                p->comm, task_pid_nr(p), cpu,
-                                p->state, p->flags);
-        }
-        write_unlock_irq(&tasklist_lock);
+        read_lock_irq(&tasklist_lock);
+        do_each_thread(g, p) {
+                if (!p->on_rq)
+                        continue;
+                /*
+                 * We do the check with unlocked task_rq(p)->lock.
+                 * Order the reading to do not warn about a task,
+                 * which was running on this cpu in the past, and
+                 * it's just been woken on another cpu.
+                 */
+                rmb();
+                if (task_cpu(p) != dead_cpu)
+                        continue;
+
+                pr_warn("Task %s (pid=%d) is on cpu %d (state=%ld, flags=%x)\n",
+                        p->comm, task_pid_nr(p), dead_cpu, p->state, p->flags);
+        } while_each_thread(g, p);
+        read_unlock_irq(&tasklist_lock);
 }
 
 struct take_cpu_down_param {