Re: [PATCH V5 0/9] Fixes for vhost metadata acceleration
From: Jason Gunthorpe <jgg@ziepe.ca>
Date: 2019-08-13 11:57:11
Also in:
kvm, linux-mm, lkml
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