Re: Linux 3.4 released

[Tejun Heo <tj@kernel.org>]

Hello, Jörg-Volker.

Please always use reply-to-all.

On Tue, May 22, 2012 at 09:50:10PM +0200, Jörg-Volker Peetz wrote:
> no, changing to  printk(KERN_CRIT "XXX: ...", ...)  in kernel/workqueue.c didn't
> print anything I could read. Would it appear before the "panic screen"? But I'm
> not able to scroll back.
> The Panic screen starts with

It should appear right above BUG:.  Can you please try the following
instead?

Thanks.

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 5abf42f..57c33ef 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1096,10 +1096,18 @@ queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work)
 }
 EXPORT_SYMBOL_GPL(queue_work_on);
 
+#include <linux/uaccess.h>
 static void delayed_work_timer_fn(unsigned long __data)
 {
 	struct delayed_work *dwork = (struct delayed_work *)__data;
 	struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work);
+	unsigned long v;
+
+	if (probe_kernel_read(&v, &cwq->wq, sizeof(v))) {
+		printk(KERN_CRIT "XXX delayed_work_timer_fn: cwq %p, fn=%pf\n",
+		       cwq, dwork->work.func);
+		return;
+	}
 
 	__queue_work(smp_processor_id(), cwq->wq, &dwork->work);
 }