Bug#801925: NULL pointer dereference: IP: [<f828a00c>] sr_runtime_suspend+0xc/0x20 [sr_mod]

[Alan Stern <stern@rowland.harvard.edu>]

On Tue, 9 Feb 2016, Alexandre Rossi wrote:

> Hi,
> 
> netconsole does not seem to work so early in the boot process this time.
> 
> > As this is Linux 4.3 and not 4.4, I guess this is a different problem
> > though. Alexandre, where you able to capture the stack trace? I’d submit
> > a new bug report with this.
> 
> Here is a photo. Please ping me if you need to test some debugging patches.

It looks like the problem occurs in blk_post_runtime_resume().  Since 
there have been recent changes to this routine, it's hard to tell 
whether you're using the most up-to-date code.

In particular, the first few lines of blk_post_runtime_resume() in 
block/blk-core.c should look like this:

void blk_post_runtime_resume(struct request_queue *q, int err)
{
	if (!q->dev)
		return;

The test was introduced by commit 4fd41a8552af ("SCSI: Fix NULL pointer
dereference in runtime PM"), which was added to the mainline kernel
between 4.3 and 4.4.  I don't know what the commit ID would be for a
.stable kernel.

Alan Stern