On Tue, Aug 13, 2019 at 04:31:07PM +0800, Jason Wang wrote: > What kind of issues do you see? Spinlock is to synchronize GUP with MMU > notifier in this series. A GUP that can't sleep can't pagefault which makes it a really weird pattern > Btw, back to the original question. May I know why synchronize_rcu() is not > suitable? Consider: We already went over this. You'd need to determine it doesn't somehow deadlock the mm on reclaim paths. Maybe it is OK, the rcq_gq_wq is marked WQ_MEM_RECLAIM at least.. I also think Michael was concerned about the latency spikes a long RCU delay would cause. Jason
