Re: [4.2] commit d59cfc09c32 (sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem) causes regression for libvirt/kvm

From: Tejun Heo
Date: Tue Sep 15 2015 - 18:28:19 EST


Hello,

On Tue, Sep 15, 2015 at 02:38:30PM -0700, Paul E. McKenney wrote:
> I did take a shot at adding the rcu_sync stuff during this past merge
> window, but it did not converge quickly enough to make it. It looks
> quite good for the next merge window. There have been changes in most
> of the relevant areas, so probably best to just try them and see which
> works best.

Heh, I'm having a bit of trouble following. Are you saying that the
changes would be too big for -stable? If so, I'll send out reverts of
the culprit patches and then reapply them for this cycle so that it
can land together with the rcu changes in the next merge window, but
it'd be great to find out whether the rcu changes are enough for the
issue that Christian is seeing to go away. If not, I'll switch to a
different locking scheme and mark those patches w/ stable tag.

Thanks!

--
tejun
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