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

Jason Wang
Thu, 07 Mar 2019 02:45:57 -0000

On 2019/3/7 ??12:31, 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