Re: [PATCH v2 1/2] mm: Export nr_swap_pages

Johannes Weiner
2015-12-07T16:48:47Z

On Mon, Dec 07, 2015 at 02:48:12PM +0100, Michal Hocko wrote:
> On Fri 04-12-15 15:58:53, Chris Wilson wrote:
> > Some modules, like i915.ko, use swappable objects and may try to swap
> > them out under memory pressure (via the shrinker). Before doing so, they
> > want to check using get_nr_swap_pages() to see if any swap space is
> > available as otherwise they will waste time purging the object from the
> > device without recovering any memory for the system. This requires the
> > nr_swap_pages counter to be exported to the modules.
>
> I guess it should be sufficient to change get_nr_swap_pages into a real
> function and export it rather than giving the access to the counter
> directly?

What do you mean by "sufficient"? That is actually more work.

It should be sufficient to just export the counter.