[PATCH] powerpc: Set the correct kernel taint on machine check errors.

[PATCH] powerpc: Set the correct kernel taint on machine check errors.

[Daniel Axtens]

This means the 'M' flag will work properly when the kernel prints a backtrace.

Signed-off-by: Daniel Axtens <dja@axtens.net>
---
 arch/powerpc/kernel/traps.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 6530f1b..37de90f 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -297,6 +297,8 @@ long machine_check_early(struct pt_regs *regs)
 
 	__this_cpu_inc(irq_stat.mce_exceptions);
 
+	add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE);
+
 	if (cur_cpu_spec && cur_cpu_spec->machine_check_early)
 		handled = cur_cpu_spec->machine_check_early(regs);
 	return handled;
-- 
2.1.4

Re: [PATCH] powerpc: Set the correct kernel taint on machine check errors.

[Michael Ellerman]

On Mon, 2015-06-15 at 13:25 +1000, Daniel Axtens wrote:
> This means the 'M' flag will work properly when the kernel prints a backtrace.
> 
> Signed-off-by: Daniel Axtens <dja@axtens.net>
> ---
>  arch/powerpc/kernel/traps.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> index 6530f1b..37de90f 100644
> --- a/arch/powerpc/kernel/traps.c
> +++ b/arch/powerpc/kernel/traps.c
> @@ -297,6 +297,8 @@ long machine_check_early(struct pt_regs *regs)
>  
>  	__this_cpu_inc(irq_stat.mce_exceptions);
>  
> +	add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE);

I'm not sure about the lockdep bit.

I guess it's safer to just declare it fubar.

Does this fix a bug, or just nice to have?

cheers

Re: [PATCH] powerpc: Set the correct kernel taint on machine check errors.

[Daniel Axtens]

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On Wed, 2015-06-24 at 15:00 +1000, Michael Ellerman wrote:
> On Mon, 2015-06-15 at 13:25 +1000, Daniel Axtens wrote:
> > This means the 'M' flag will work properly when the kernel prints a backtrace.
> > 
> > Signed-off-by: Daniel Axtens <dja@axtens.net>
> > ---
> >  arch/powerpc/kernel/traps.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> > index 6530f1b..37de90f 100644
> > --- a/arch/powerpc/kernel/traps.c
> > +++ b/arch/powerpc/kernel/traps.c
> > @@ -297,6 +297,8 @@ long machine_check_early(struct pt_regs *regs)
> >  
> >  	__this_cpu_inc(irq_stat.mce_exceptions);
> >  
> > +	add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE);
> 
> I'm not sure about the lockdep bit.
> 
> I guess it's safer to just declare it fubar.
> 
I'm also not sure; I was matching x86 behaviour.

> Does this fix a bug, or just nice to have?
> 
If you consider having the taint bits set incorrectly to be a bug, then
it fixes a bug. Otherwise, it's just nice debug info to have: when we
get a traceback with M set that isn't obviously related to a MCE we are
forewarned.

> cheers
> 
> 

-- 
Regards,
Daniel

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Re: powerpc: Set the correct kernel taint on machine check errors.

[Michael Ellerman]

On Mon, 2015-15-06 at 03:25:19 UTC, Daniel Axtens wrote:
> This means the 'M' flag will work properly when the kernel prints a backtrace.
> 
> Signed-off-by: Daniel Axtens <dja@axtens.net>

Applied to powerpc fixes, thanks.

https://git.kernel.org/cgit/linux/kernel/git/powerpc/linux.git/commit/?h=fixes&id=27ea2c420cad57386c25668cb9a9f0f082635586

cheers