On Tue 04-07-17 14:48:56, Thomas Gleixner wrote: > On Tue, 4 Jul 2017, Michal Hocko wrote: > > On Tue 04-07-17 11:32:33, Thomas Gleixner wrote: > > > The rework of the cpu hotplug locking unearthed potential deadlocks with > > > the memory hotplug locking code. > > > > > > The solution for these is to rework the memory hotplug locking code as well > > > and take the cpu hotplug lock before the memory hotplug lock in > > > mem_hotplug_begin(), but this will cause a recursive locking of the cpu > > > hotplug lock when the memory hotplug code calls lru_add_drain_all(). > > > > > > Split out the inner workings of lru_add_drain_all() into > > > lru_add_drain_all_cpuslocked() so this function can be invoked from the > > > memory hotplug code with the cpu hotplug lock held. > > > > You have added callers in the later patch in the series AFAICS which > > is OK but I think it would be better to have them in this patch > > already. Nothing earth shattering (maybe a rebase artifact). > > The requirement for changing that comes with the extra hotplug locking in > mem_hotplug_begin(). That is required to establish the proper lock order > and then causes the recursive locking in the next patch. Adding the caller > here would be wrong, because then lru_add_drain_all_cpuslocked() would be > called unprotected. Hens and eggs as usual :) Yeah, you are right. My bad I should have noticed that. -- Michal Hocko SUSE Labs -- 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>
