Commit a2a36488 authored by Keith Busch's avatar Keith Busch Committed by Linus Torvalds
Browse files

mm/vmscan: Consider anonymous pages without swap 

Reclaim anonymous pages if a migration path is available now that demotion
provides a non-swap recourse for reclaiming anon pages.

Note that this check is subtly different from the can_age_anon_pages()
checks.  This mechanism checks whether a specific page in a specific
context can actually be reclaimed, given current swap space and cgroup
limits.

can_age_anon_pages() is a much simpler and more preliminary check which
just says whether there is a possibility of future reclaim.

[kbusch@kernel.org: v11]
  Link: https://lkml.kernel.org/r/20210715055145.195411-8-ying.huang@intel.com
  Link: https://lkml.kernel.org/r/20210721063926.3024591-7-ying.huang@intel.com

Link: https://lkml.kernel.org/r/20210715055145.195411-8-ying.huang@intel.com


Cc: Keith Busch <kbusch@kernel.org>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: default avatar"Huang, Ying" <ying.huang@intel.com>
Reviewed-by: default avatarYang Shi <shy828301@gmail.com>
Reviewed-by: default avatarZi Yan <ziy@nvidia.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Wei Xu <weixugc@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2f368a9f

mm/vmscan.c

+30 −4
Original line number Diff line number Diff line
@@ -524,7 +524,7 @@ static long add_nr_deferred(long nr, struct shrinker *shrinker, 


static bool can_demote(int nid, struct scan_control *sc)

{

	if (sc->no_demotion)

	if (sc && sc->no_demotion)

		return false;

	if (next_demotion_node(nid) == NUMA_NO_NODE)

		return false;
@@ -533,6 +533,31 @@ static bool can_demote(int nid, struct scan_control *sc) 
	return false;

}



static inline bool can_reclaim_anon_pages(struct mem_cgroup *memcg,

					  int nid,

					  struct scan_control *sc)

{

	if (memcg == NULL) {

		/*

		 * For non-memcg reclaim, is there

		 * space in any swap device?

		 */

		if (get_nr_swap_pages() > 0)

			return true;

	} else {

		/* Is the memcg below its swap limit? */

		if (mem_cgroup_get_nr_swap_pages(memcg) > 0)

			return true;

	}



	/*

	 * The page can not be swapped.

	 *

	 * Can it be reclaimed from this node via demotion?

	 */

	return can_demote(nid, sc);

}



/*

 * This misses isolated pages which are not accounted for to save counters.

 * As the data only determines if reclaim or compaction continues, it is
@@ -544,7 +569,7 @@ unsigned long zone_reclaimable_pages(struct zone *zone) 


	nr = zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_FILE) +

		zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_FILE);

	if (get_nr_swap_pages() > 0)

	if (can_reclaim_anon_pages(NULL, zone_to_nid(zone), NULL))

		nr += zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_ANON) +

			zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_ANON);
@@ -2541,6 +2566,7 @@ enum scan_balance { 
static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,

			   unsigned long *nr)

{

	struct pglist_data *pgdat = lruvec_pgdat(lruvec);

	struct mem_cgroup *memcg = lruvec_memcg(lruvec);

	unsigned long anon_cost, file_cost, total_cost;

	int swappiness = mem_cgroup_swappiness(memcg);
@@ -2551,7 +2577,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, 
	enum lru_list lru;



	/* If we have no swap space, do not bother scanning anon pages. */

	if (!sc->may_swap || mem_cgroup_get_nr_swap_pages(memcg) <= 0) {

	if (!sc->may_swap || !can_reclaim_anon_pages(memcg, pgdat->node_id, sc)) {

		scan_balance = SCAN_FILE;

		goto out;

	}
@@ -2929,7 +2955,7 @@ static inline bool should_continue_reclaim(struct pglist_data *pgdat, 
	 */

	pages_for_compaction = compact_gap(sc->order);

	inactive_lru_pages = node_page_state(pgdat, NR_INACTIVE_FILE);

	if (get_nr_swap_pages() > 0)

	if (can_reclaim_anon_pages(NULL, pgdat->node_id, sc))

		inactive_lru_pages += node_page_state(pgdat, NR_INACTIVE_ANON);



	return inactive_lru_pages > pages_for_compaction;