Re: [RFC PATCH V2 5/5] vhost: access vq metadata through kernel virtual address

[Jason Wang]

On 2019/3/7 äå12:31, Michael S. Tsirkin wrote:
> > +static void vhost_set_vmap_dirty(struct vhost_vmap *used)
> > +{
> > +	int i;
> > +
> > +	for (i = 0; i < used->npages; i++)
> > +		set_page_dirty_lock(used->pages[i]);
> This seems to rely on page lock to mark page dirty.
>
> Could it happen that page writeback will check the
> page, find it clean, and then you mark it dirty and then
> invalidate callback is called?

Yes. But does this break anything? The page is still there, we just 
remove a kernel mapping to it.

Thanks