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

On Mon, Dec 8, 2014 at 3:58 PM, Anton Blanchard [off-list ref] wrote:

Hi Ingo,

quoted

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