Re: Random panic in load_balance() with 3.16-rc

[Linus Torvalds]

On Tue, Jul 22, 2014 at 8:53 PM, Michel DÃnzer <michel@xxxxxxxxxxx> wrote:
>
> Just happened again with the same change on top of 3.16-rc6.

The (maybe) related bugzilla entry is just odd. Bruno Wolff reports
that the BUG_ON() in his added patch triggers:

+               cpumask_clear(sched_group_cpus(sg));
+               sg->sgc->capacity = 0;
+               BUG_ON(!cpumask_empty(sched_group_cpus(sg)));

where it *just* did a cpumask_clear(), and now the BUG_ON() triggers
that it's no longer empty?

That would imply an allocation error, but all the sched groups seem to
be properly allocated with the proper addition of cpumask_size().

And his config file even has NR_CPUS being 32, so it should be a
single word of bitmap, which triggers all the simple code.

Completely insane, in other words.

           Linus
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