On Thu, Jan 13, 2011 at 4:53 AM, Gleb Natapov <gleb@xxxxxxxxxx> wrote: > > I implemented get_user_pages_nowait() on top of your patch. In my testing > it works as expected when used inside KVM. Does this looks OK to you? It looks reasonable, although I suspect the subtle behavior wrt the mmap_sem means that you should not expose the magic bare FAULT_FLAG_ALLOW_RETRY flag to the __get_user_pages() thing. It's just too easy to introduce bugs, methinks. So I'd suggest - drop FOLL_RETRY - make FOLL_NOWAIT set both (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_NOWAIT) and that way the get_user_pages() thing will never release the mmap_sem, and you never have any subtle locking issues for that particular interface. But some other VM person should look at it too. Linus -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html