1 files changed, 29 insertions, 4 deletions

diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
index 678a5120ee30..4c5dead0c239 100644
--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -110,12 +110,12 @@ static inline void check_stack(void)
 static void
 stack_trace_call(unsigned long ip, unsigned long parent_ip)
 {
-        int cpu, resched;
+        int cpu;
 
         if (unlikely(!ftrace_enabled || stack_trace_disabled))
                 return;
 
-        resched = ftrace_preempt_disable();
+        preempt_disable_notrace();
 
         cpu = raw_smp_processor_id();
         /* no atomic needed, we only modify this variable by this cpu */
@@ -127,7 +127,7 @@ stack_trace_call(unsigned long ip, unsigned long parent_ip)
  out:
         per_cpu(trace_active, cpu)--;
         /* prevent recursion in schedule */
-        ftrace_preempt_enable(resched);
+        preempt_enable_notrace();
 }
 
 static struct ftrace_ops trace_ops __read_mostly =
@@ -157,6 +157,7 @@ stack_max_size_write(struct file *filp, const char __user *ubuf,
         unsigned long val, flags;
         char buf[64];
         int ret;
+        int cpu;
 
         if (count >= sizeof(buf))
                 return -EINVAL;
@@ -171,9 +172,20 @@ stack_max_size_write(struct file *filp, const char __user *ubuf,
                 return ret;
 
         local_irq_save(flags);
+
+        /*
+         * In case we trace inside arch_spin_lock() or after (NMI),
+         * we will cause circular lock, so we also need to increase
+         * the percpu trace_active here.
+         */
+        cpu = smp_processor_id();
+        per_cpu(trace_active, cpu)++;
+
         arch_spin_lock(&max_stack_lock);
         *ptr = val;
         arch_spin_unlock(&max_stack_lock);
+
+        per_cpu(trace_active, cpu)--;
         local_irq_restore(flags);
 
         return count;
@@ -183,6 +195,7 @@ static const struct file_operations stack_max_size_fops = {
         .open           = tracing_open_generic,
         .read           = stack_max_size_read,
         .write          = stack_max_size_write,
+        .llseek         = default_llseek,
 };
 
 static void *
@@ -206,7 +219,13 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
 
 static void *t_start(struct seq_file *m, loff_t *pos)
 {
+        int cpu;
+
         local_irq_disable();
+
+        cpu = smp_processor_id();
+        per_cpu(trace_active, cpu)++;
+
         arch_spin_lock(&max_stack_lock);
 
         if (*pos == 0)
@@ -217,7 +236,13 @@ static void *t_start(struct seq_file *m, loff_t *pos)
 
 static void t_stop(struct seq_file *m, void *p)
 {
+        int cpu;
+
         arch_spin_unlock(&max_stack_lock);
+
+        cpu = smp_processor_id();
+        per_cpu(trace_active, cpu)--;
+
         local_irq_enable();
 }
 
@@ -225,7 +250,7 @@ static int trace_lookup_stack(struct seq_file *m, long i)
 {
         unsigned long addr = stack_dump_trace[i];
 
-        return seq_printf(m, "%pF\n", (void *)addr);
+        return seq_printf(m, "%pS\n", (void *)addr);
 }
 
 static void print_disabled(struct seq_file *m)