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Commit a4d3e9e7 authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds
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mm: vmscan: fix force-scanning small targets without swap 



Without swap, anonymous pages are not scanned.  As such, they should not
count when considering force-scanning a small target if there is no swap.

Otherwise, targets are not force-scanned even when their effective scan
number is zero and the other conditions--kswapd/memcg--apply.

This fixes 246e87a9 ("memcg: fix get_scan_count() for small
targets").

[akpm@linux-foundation.org: fix comment]
Signed-off-by: default avatarJohannes Weiner <jweiner@redhat.com>
Acked-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: default avatarMichal Hocko <mhocko@suse.cz>
Cc: Ying Han <yinghan@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: default avatarMel Gorman <mel@csn.ul.ie>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d4c32f35

mm/vmscan.c

+12 −15
Original line number Diff line number Diff line
@@ -1808,23 +1808,15 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc, 
	u64 fraction[2], denominator;

	enum lru_list l;

	int noswap = 0;

	int force_scan = 0;

	bool force_scan = false;

	unsigned long nr_force_scan[2];





	anon  = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) +

		zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON);

	file  = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) +

		zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE);



	if (((anon + file) >> priority) < SWAP_CLUSTER_MAX) {

		/* kswapd does zone balancing and need to scan this zone */

	/* kswapd does zone balancing and needs to scan this zone */

	if (scanning_global_lru(sc) && current_is_kswapd())

			force_scan = 1;

		force_scan = true;

	/* memcg may have small limit and need to avoid priority drop */

	if (!scanning_global_lru(sc))

			force_scan = 1;

	}

		force_scan = true;



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

	if (!sc->may_swap || (nr_swap_pages <= 0)) {
@@ -1837,6 +1829,11 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc, 
		goto out;

	}



	anon  = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) +

		zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON);

	file  = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) +

		zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE);



	if (scanning_global_lru(sc)) {

		free  = zone_page_state(zone, NR_FREE_PAGES);

		/* If we have very few page cache pages,