On Sun, 29 Sep 2013 20:36:34 +0200 Oleg Nesterov <oleg@xxxxxxxxxx> wrote: > Why? Say, percpu_rw_semaphore, or upcoming changes in get_online_cpus(), > (Peter, I think they should be unified anyway, but lets ignore this for > now). Or freeze_super() (which currently looks buggy), perhaps something > else. This pattern > Just so I'm clear to what you are trying to implement... This is to handle the case (as Paul said) to see changes to state by RCU and back again? That is, it isn't enough to see that the state changed to something (like SLOW MODE), but we also need a way to see it change back? With get_online_cpus(), we need to see the state where it changed to "performing hotplug" where holders need to go into the slow path, and then also see the state change to "no longe performing hotplug" and the holders now go back to fast path. Is this the rational for this email? Thanks, -- Steve -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>