[PATCH] powerpc: secondary CPUs signal to master before setting active and online (fixes kernel BUG at kernel/smpboot.c:134!)

[Linus Torvalds]

On Mon, Dec 8, 2014 at 3:58 PM, Anton Blanchard <anton at samba.org> wrote:
> Hi Ingo,
>
>> At that point I thought the previous task_cpu() was somewhat ingrained
>> in the scheduler and came up with the patch. If not, we could go on a
>> hunt to see what else needs fixing.
>
> I had another look. The scheduled does indeed make assumptions about the
> previous task_cpu, but we have a hammer to fix it up called
> select_fallback_rq.
>
> I annotated select_fallback_rq, and did hit a case where the CPU was
> not active. ppc64 patch below.

Anton, I'll assume I will get this through the usual powerpc pull requests?

> I think x86 have a similar (although harder to hit) issue.

Ingo?

                         Linus