On Tue, Dec 03, 2024 at 08:02:26PM +0100, Uladzislau Rezki wrote: I think there are a few other things we can try here.
First, if the copy is small (and I still don't have an answer to that ...), we can skip the vmalloc lookup if the copy doesn't cross a page boundary. Second, we could try storing this in a maple tree rather than an rbtree. That gives us RCU protected lookups rather than under a spinlock. It might even be worth going to a rwlock first, in case the problem is that there's severe lock contention. But I've asked for data on spinlock contention and not received an answer on that either, so I don't know what to suggest. Anyway, NACK to the original patch; that's just a horrible idea.
