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SubjectRe: [PATCH] keep rd->online and cpu_online_map in sync
>>> On Mon, Mar 10, 2008 at  6:03 PM, in message <200803102303.28660.rjw@sisk.pl>,
"Rafael J. Wysocki" <rjw@sisk.pl> wrote:
> On Monday, 10 of March 2008, Suresh Siddha wrote:
>> On Mon, Mar 10, 2008 at 09:39:34AM -0400, Gregory Haskins wrote:
>> > keep rd->online and cpu_online_map in sync
>> >
>> > It is possible to allow the root-domain cache of online cpus to
>> > become out of sync with the global cpu_online_map. This is because we
>> > currently trigger removal of cpus too early in the notifier chain.
>> > Other DOWN_PREPARE handlers may in fact run and reconfigure the
>> > root-domain topology, thereby stomping on our own offline handling.
>> >
>> > The end result is that rd->online may become out of sync with
>> > cpu_online_map, which results in potential task misrouting.
>> >
>> > So change the offline handling to be more tightly coupled with the
>> > global offline process by triggering on CPU_DYING intead of
>> > CPU_DOWN_PREPARE.
>> >
>> > Signed-off-by: Gregory Haskins <ghaskins@novell.com>
>> > ---
>> >
>> > kernel/sched.c | 2 +-
>> > 1 files changed, 1 insertions(+), 1 deletions(-)
>> >
>> > diff --git a/kernel/sched.c b/kernel/sched.c
>> > index 52b9867..a616fa1 100644
>> > --- a/kernel/sched.c
>> > +++ b/kernel/sched.c
>> > @@ -5881,7 +5881,7 @@ migration_call(struct notifier_block *nfb, unsigned
> long action, void *hcpu)
>> > spin_unlock_irq(&rq->lock);
>> > break;
>> >
>> > - case CPU_DOWN_PREPARE:
>> > + case CPU_DYING:
>>
>> Don't we need to take care of CPU_DYING_FROZEN aswell?
>
> Well, I'd say we do.

Should I add that to the patch as well then?

>
>> > /* Update our root-domain */
>> > rq = cpu_rq(cpu);
>> > spin_lock_irqsave(&rq->lock, flags);
>> >




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