Commit 89b5fae5 authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds
Browse files

mm: vmscan: distinguish global reclaim from global LRU scanning 



The traditional zone reclaim code is scanning the per-zone LRU lists
during direct reclaim and kswapd, and the per-zone per-memory cgroup LRU
lists when reclaiming on behalf of a memory cgroup limit.

Subsequent patches will convert the traditional reclaim code to reclaim
exclusively from the per-memory cgroup LRU lists.  As a result, using
the predicate for which LRU list is scanned will no longer be
appropriate to tell global reclaim from limit reclaim.

This patch adds a global_reclaim() predicate to tell direct/kswapd
reclaim from memory cgroup limit reclaim and substitutes it in all
places where currently scanning_global_lru() is used for that.

Signed-off-by: default avatarJohannes Weiner <jweiner@redhat.com>
Reviewed-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: default avatarMichal Hocko <mhocko@suse.cz>
Reviewed-by: default avatarKirill A. Shutemov <kirill@shutemov.name>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Ying Han <yinghan@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9f3a0d09

mm/vmscan.c

+37 −25
Original line number Diff line number Diff line
@@ -153,9 +153,25 @@ static LIST_HEAD(shrinker_list); 
static DECLARE_RWSEM(shrinker_rwsem);



#ifdef CONFIG_CGROUP_MEM_RES_CTLR

#define scanning_global_lru(sc)	(!(sc)->mem_cgroup)

static bool global_reclaim(struct scan_control *sc)

{

	return !sc->mem_cgroup;

}



static bool scanning_global_lru(struct scan_control *sc)

{

	return !sc->mem_cgroup;

}

#else

#define scanning_global_lru(sc)	(1)

static bool global_reclaim(struct scan_control *sc)

{

	return true;

}



static bool scanning_global_lru(struct scan_control *sc)

{

	return true;

}

#endif



static struct zone_reclaim_stat *get_reclaim_stat(struct zone *zone,
@@ -994,7 +1010,7 @@ keep_lumpy: 
	 * back off and wait for congestion to clear because further reclaim

	 * will encounter the same problem

	 */

	if (nr_dirty && nr_dirty == nr_congested && scanning_global_lru(sc))

	if (nr_dirty && nr_dirty == nr_congested && global_reclaim(sc))

		zone_set_flag(zone, ZONE_CONGESTED);



	free_hot_cold_page_list(&free_pages, 1);
@@ -1313,7 +1329,7 @@ static int too_many_isolated(struct zone *zone, int file, 
	if (current_is_kswapd())

		return 0;



	if (!scanning_global_lru(sc))

	if (!global_reclaim(sc))

		return 0;



	if (file) {
@@ -1491,6 +1507,12 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, 
	if (scanning_global_lru(sc)) {

		nr_taken = isolate_pages_global(nr_to_scan, &page_list,

			&nr_scanned, sc->order, reclaim_mode, zone, 0, file);

	} else {

		nr_taken = mem_cgroup_isolate_pages(nr_to_scan, &page_list,

			&nr_scanned, sc->order, reclaim_mode, zone,

			sc->mem_cgroup, 0, file);

	}

	if (global_reclaim(sc)) {

		zone->pages_scanned += nr_scanned;

		if (current_is_kswapd())

			__count_zone_vm_events(PGSCAN_KSWAPD, zone,
@@ -1498,14 +1520,6 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, 
		else

			__count_zone_vm_events(PGSCAN_DIRECT, zone,

					       nr_scanned);

	} else {

		nr_taken = mem_cgroup_isolate_pages(nr_to_scan, &page_list,

			&nr_scanned, sc->order, reclaim_mode, zone,

			sc->mem_cgroup, 0, file);

		/*

		 * mem_cgroup_isolate_pages() keeps track of

		 * scanned pages on its own.

		 */

	}



	if (nr_taken == 0) {
@@ -1646,18 +1660,16 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone, 
						&pgscanned, sc->order,

						reclaim_mode, zone,

						1, file);

		zone->pages_scanned += pgscanned;

	} else {

		nr_taken = mem_cgroup_isolate_pages(nr_pages, &l_hold,

						&pgscanned, sc->order,

						reclaim_mode, zone,

						sc->mem_cgroup, 1, file);

		/*

		 * mem_cgroup_isolate_pages() keeps track of

		 * scanned pages on its own.

		 */

	}



	if (global_reclaim(sc))

		zone->pages_scanned += pgscanned;



	reclaim_stat->recent_scanned[file] += nr_taken;



	__count_zone_vm_events(PGREFILL, zone, pgscanned);
@@ -1827,7 +1839,7 @@ static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, 


static int vmscan_swappiness(struct scan_control *sc)

{

	if (scanning_global_lru(sc))

	if (global_reclaim(sc))

		return vm_swappiness;

	return mem_cgroup_swappiness(sc->mem_cgroup);

}
@@ -1862,9 +1874,9 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc, 
	 * latencies, so it's better to scan a minimum amount there as

	 * well.

	 */

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

	if (current_is_kswapd())

		force_scan = true;

	if (!scanning_global_lru(sc))

	if (!global_reclaim(sc))

		force_scan = true;



	/* If we have no swap space, do not bother scanning anon pages. */
@@ -1881,7 +1893,7 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc, 
	file  = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) +

		zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE);



	if (scanning_global_lru(sc)) {

	if (global_reclaim(sc)) {

		free  = zone_page_state(zone, NR_FREE_PAGES);

		/* If we have very few page cache pages,

		   force-scan anon pages. */
@@ -2114,7 +2126,7 @@ static bool shrink_zones(int priority, struct zonelist *zonelist, 
		 * Take care memory controller reclaiming has small influence

		 * to global LRU.

		 */

		if (scanning_global_lru(sc)) {

		if (global_reclaim(sc)) {

			if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))

				continue;

			if (zone->all_unreclaimable && priority != DEF_PRIORITY)
@@ -2212,7 +2224,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, 
	get_mems_allowed();

	delayacct_freepages_start();



	if (scanning_global_lru(sc))

	if (global_reclaim(sc))

		count_vm_event(ALLOCSTALL);



	for (priority = DEF_PRIORITY; priority >= 0; priority--) {
@@ -2226,7 +2238,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, 
		 * Don't shrink slabs when reclaiming memory from

		 * over limit cgroups

		 */

		if (scanning_global_lru(sc)) {

		if (global_reclaim(sc)) {

			unsigned long lru_pages = 0;

			for_each_zone_zonelist(zone, z, zonelist,

					gfp_zone(sc->gfp_mask)) {
@@ -2288,7 +2300,7 @@ out: 
		return 0;



	/* top priority shrink_zones still had more to do? don't OOM, then */

	if (scanning_global_lru(sc) && !all_unreclaimable(zonelist, sc))

	if (global_reclaim(sc) && !all_unreclaimable(zonelist, sc))

		return 1;



	return 0;

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