sched: use show_regs() to improve __schedule_bug() output

A full register dump along with stack backtrace would make the
"scheduling while atomic" message more helpful. Use show_regs() instead
of dump_stack() for this. We already know we're atomic in here (that is
why this function was called) so show_regs()'s atomicity expectations
are guaranteed.

Also, modify the output of the "BUG: scheduling while atomic:" header a
bit to keep task->comm and task->pid together and preempt_count() after
them.

Signed-off-by: Satyam Sharma <satyam@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 11 insertions, 3 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index af02a4de069b..d1e6663d3ab0 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -66,6 +66,7 @@
 #include <linux/pagemap.h>
 
 #include <asm/tlb.h>
+#include <asm/irq_regs.h>
 
 /*
  * Scheduler clock - returns current time in nanosec units.
@@ -3507,12 +3508,19 @@ EXPORT_SYMBOL(sub_preempt_count);
  */
 static noinline void __schedule_bug(struct task_struct *prev)
 {
-        printk(KERN_ERR "BUG: scheduling while atomic: %s/0x%08x/%d\n",
-                prev->comm, preempt_count(), task_pid_nr(prev));
+        struct pt_regs *regs = get_irq_regs();
+
+        printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
+                prev->comm, prev->pid, preempt_count());
+
         debug_show_held_locks(prev);
         if (irqs_disabled())
                 print_irqtrace_events(prev);
-        dump_stack();
+
+        if (regs)
+                show_regs(regs);
+        else
+                dump_stack();
 }
 
 /*