Merge tag 'trace-v4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux...

[linux-2.6-block.git] / kernel / trace / trace_stack.c

diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
index 0bd212af406c49fc64ad308112e9ad7fab1eb4ff..dda9e6742950305f36fbe920f9fe0c6f68d83fbf 100644 (file)
--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -91,9 +91,19 @@ check_stack(unsigned long ip, unsigned long *stack)
        if (!object_is_on_stack(stack))
                return;
 
+       /* Can't do this from NMI context (can cause deadlocks) */
+       if (in_nmi())
+               return;
+
        local_irq_save(flags);
        arch_spin_lock(&stack_trace_max_lock);
 
+       /*
+        * RCU may not be watching, make it see us.
+        * The stack trace code uses rcu_sched.
+        */
+       rcu_irq_enter();
+
        /* In case another CPU set the tracer_frame on us */
        if (unlikely(!frame_size))
                this_size -= tracer_frame;
@@ -175,6 +185,7 @@ check_stack(unsigned long ip, unsigned long *stack)
        }
 
  out:
+       rcu_irq_exit();
        arch_spin_unlock(&stack_trace_max_lock);
        local_irq_restore(flags);
 }