Re: [ANNOUNCE] v5.9-rc3-rt3

[Sebastian Andrzej Siewior]

On 2020-09-09 07:45:22 [+0200], Mike Galbraith wrote:
> On Wed, 2020-09-09 at 05:12 +0200, Mike Galbraith wrote:
> > On Wed, 2020-09-02 at 17:55 +0200, Sebastian Andrzej Siewior wrote:
> > >
> > > Known issues
> > >      - It has been pointed out that due to changes to the printk code the
> > >        internal buffer representation changed. This is only an issue if tools
> > >        like `crash' are used to extract the printk buffer from a kernel memory
> > >        image.
> >
> > Ouch.  While installing -rt5 on lappy via nfs, -rt5 server box exploded
> > leaving nada in logs.  I have a nifty crash dump of the event, but...
> 
> After convincing crash (with club) that it didn't _really_ need a
> log_buf, nfs had nothing to do with the crash, it was nouveau.

okay. Line 280 is hard to understand. My guess is that we got a pointer
and then the boom occurred but I can't tell why/how. A few lines later
there is args->x = y…
Do you see the lockdep splat without nouveau?

> crash> bt -l
> PID: 2146   TASK: ffff994c7fad0000  CPU: 0   COMMAND: "X"
>  #0 [ffffbfffc11a76c8] machine_kexec at ffffffffb7064879
>     /backup/usr/local/src/kernel/linux-master-rt/./include/linux/ftrace.h: 792
>  #1 [ffffbfffc11a7710] __crash_kexec at ffffffffb7173622
>     /backup/usr/local/src/kernel/linux-master-rt/kernel/kexec_core.c: 963
>  #2 [ffffbfffc11a77d0] crash_kexec at ffffffffb7174920
>     /backup/usr/local/src/kernel/linux-master-rt/./arch/x86/include/asm/atomic.h: 41
>  #3 [ffffbfffc11a77e0] oops_end at ffffffffb702716f
>     /backup/usr/local/src/kernel/linux-master-rt/arch/x86/kernel/dumpstack.c: 342
>  #4 [ffffbfffc11a7800] exc_general_protection at ffffffffb79a2fc6
>     /backup/usr/local/src/kernel/linux-master-rt/arch/x86/kernel/traps.c: 82
>  #5 [ffffbfffc11a7890] asm_exc_general_protection at ffffffffb7a00a1e
>     /backup/usr/local/src/kernel/linux-master-rt/./arch/x86/include/asm/idtentry.h: 532
>  #6 [ffffbfffc11a78a0] nvif_object_ctor at ffffffffc07ee6a7 [nouveau]
>     /backup/usr/local/src/kernel/linux-master-rt/drivers/gpu/drm/nouveau/nvif/object.c: 280
>  #7 [ffffbfffc11a7918] __kmalloc at ffffffffb72eea12
>     /backup/usr/local/src/kernel/linux-master-rt/mm/slub.c: 261
>  #8 [ffffbfffc11a7980] nvif_object_ctor at ffffffffc07ee6a7 [nouveau]
>     /backup/usr/local/src/kernel/linux-master-rt/drivers/gpu/drm/nouveau/nvif/object.c: 280

Sebastian