powerpc/traps: Fix the message printed when stack overflows

commit 9bf3d3c upstream.

Today's message is useless:

  [   42.253267] Kernel stack overflow in process (ptrval), r1=c65500b0

This patch fixes it:

  [   66.905235] Kernel stack overflow in process sh[356], r1=c65560b0

Fixes: ad67b74 ("printk: hash addresses printed with %p")
Cc: stable@vger.kernel.org # v4.15+
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: Use task_pid_nr()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/powerpc/kernel/traps.c

@@ -1292,8 +1292,8 @@ void slb_miss_bad_addr(struct pt_regs *regs)
 
 void StackOverflow(struct pt_regs *regs)
 {
- printk(KERN_CRIT "Kernel stack overflow in process %p, r1=%lx\n",
-  current, regs->gpr[1]);
+ pr_crit("Kernel stack overflow in process %s[%d], r1=%lx\n",
+  current->comm, task_pid_nr(current), regs->gpr[1]);
  debugger(regs);
  show_regs(regs);
  panic("kernel stack overflow");