Re: [PATCH V5 0/9] Fixes for vhost metadata acceleration
From: Christoph Hellwig <hch@infradead.org>
Date: 2019-08-13 16:41:10
Also in:
kvm, linux-mm, lkml, netdev
On Tue, Aug 13, 2019 at 08:57:07AM -0300, Jason Gunthorpe wrote:
On Tue, Aug 13, 2019 at 04:31:07PM +0800, Jason Wang wrote:quoted
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
get_user_pages/get_user_pages_fast must not be called under a spinlock. We have the somewhat misnamed __get_user_page_fast that just does a lookup for existing pages and never faults for a few places that need to do that lookup from contexts where we can't sleep.