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

Linus Torvalds
2014-07-23T04:21:43Z

On Tue, Jul 22, 2014 at 8:53 PM, Michel Dänzer <michel@daenzer.net> 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