Hi Ingo, Steve, Thomas, Ingo pointed me at an issue on LKML/mainline regarding cpu-hotplug. It turns out that the issue (I believe) was related to the root-domain code that I added a few months ago. This code is also in -rt, so the bug should exist there as well. This may fix the root-cause of that s2ram bug that Mike Galbraith found and patched a while back as well. If that is the case, we can probably get rid of the "num_online_cpus()" in the update_migration code. That will require confirmation from Mike, however, as I do not have a P4 machine like his that exhibits the bug. For now, both patches should probably co-exist together. This applies to 24.3-rt3 Regards, -Greg ------------------------------ 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@xxxxxxxxxx> --- kernel/sched.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index 7547c70..24edc53 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -6082,7 +6082,7 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu) spin_unlock_irq(&rq->lock); break; - case CPU_DOWN_PREPARE: + case CPU_DYING: /* Update our root-domain */ rq = cpu_rq(cpu); spin_lock_irqsave(&rq->lock, flags); -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
