Nouveau - Jul 2017 - [regression drm/noveau] suspend to ram -> BOOM: exception RIP: drm_calc_vbltimestamp_from_scanoutpos+335

On Fri, Jul 14, 2017 at 03:36:08PM +0200, Mike Galbraith
wrote:
> Ok, a network outage gave me time to go hunting.  Indeed it is a bad
> interaction with the tree DRM merged into.  All DRM did was to slip a
> WARN_ON_ONCE() that nouveau triggers into a kernel module where such
> things no longer warn, they blow the box out of the water.  I made a
> dinky testcase module (attached), and bisected to the real root....
> 
> 19d436268dde95389c616bb3819da73f0a8b28a8 is the first bad commit
> commit 19d436268dde95389c616bb3819da73f0a8b28a8
> Author: Peter Zijlstra <peterz at infradead.org>
> Date:   Sat Feb 25 08:56:53 2017 +0100
> 
>     debug: Add _ONCE() logic to report_bug()
Urgh, is for some mysterious reason the __bug_table section of modules
ending up in RO memory?

I forever get lost in that link magic :/

On Fri, Jul 14, 2017 at 05:58:18PM +0200, Mike Galbraith
wrote:
> On Fri, 2017-07-14 at 17:50 +0200, Peter Zijlstra wrote:
> > Urgh, is for some mysterious reason the __bug_table section of modules
> > ending up in RO memory?
> > 
> > I forever get lost in that link magic :/
> 
> +1
> 
> drm.ko
>  20
__bug_table   00000630  0000000000000000  0000000000000000  0004bff3  2**0
>                   CONTENTS, ALLOC, LOAD, RELOC, READONLY, DATA
> vmlinux
>  15 __bug_table   0000ba84  ffffffff81af26c0  0000000001af26c0  00cf26c0 
2**0
>                   CONTENTS, ALLOC, LOAD, READONLY, DATA
> 
> Danged if I know... um um RELOC business mucks things up?
Argh, it shouldn't be READONLY for vmlinux either, but apparently that
is working for mysterious reasons.

Some architectures were in fact complaining that I broke that, and hence
patch:

b5effd3815cc ("debug: Fix __bug_table[] in arch linker scripts")

I think we need professional help with this linking stuff, but who to
ask?