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

[Alexandre Rossi <alexandre.rossi@gmail.com>]

Hello,

>> > 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.

Okay now I've tried with 4.4. The oops does not occur. So this is
fixed for me in 4.4.

If there is interest in backporting to 4.3, 13b438914341 ("SCSI: fix
crashes in sd and sr runtime PM") is not enough to backport. Something
in 4.4, most probably 4fd41a8552af ("SCSI: Fix NULL pointer
dereference in runtime PM") is also needed.

Thanks a lot,

Alex