Re: [PATCH 2.6.32-rc6] sched, kvm: fix race condition involvingsched_in_preempt_notifers

From: Ingo Molnar
Date: Fri Nov 13 2009 - 04:56:00 EST



* Tejun Heo <tj@xxxxxxxxxx> wrote:

> In finish_task_switch(), fire_sched_in_preempt_notifiers() is called
> after finish_lock_switch(). However, depending on architecture,
> preemption can be enabled after finish_lock_switch() which breaks the
> semantics of preempt notifiers. Move it before finish_arch_switch().
> This also makes in notifiers symmetric to out notifiers in terms of
> locking - now both are called under rq lock.
>
> NOT_SIGNED_OFF_YET
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Avi Kivity <avi@xxxxxxxxxx>
> ---
> Avi, I think kvm should be fine with this but I haven't tested it.
> Does this look okay to you? If so, can you please route this through
> kvm tree with my signoff?

I'd like to have Avi's Ack for it, but we want to do sched.c changes via
the scheduler tree.

Ingo
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