Re: [PATCH] dax: Fix missed PMD wakeups

[Matthew Wilcox]

On Wed, Jul 10, 2019 at 09:02:04PM +0200, Jan Kara wrote:
> @@ -848,7 +853,7 @@ static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev,
>  	if (unlikely(dax_is_locked(entry))) {
>  		void *old_entry = entry;
>  
> -		entry = get_unlocked_entry(xas);
> +		entry = get_unlocked_entry(xas, 0);
>  
>  		/* Entry got punched out / reallocated? */
>  		if (!entry || WARN_ON_ONCE(!xa_is_value(entry)))

I'm not sure about this one.  Are we sure there will never be a dirty
PMD entry?  Even if we can't create one today, it feels like a bit of
a landmine to leave for someone who creates one in the future.