Commit b5ead35e authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds
Browse files

mm: vmscan: naming fixes: global_reclaim() and sane_reclaim() 

Seven years after introducing the global_reclaim() function, I still have
to double take when reading a callsite.  I don't know how others do it,
this is a terrible name.

Invert the meaning and rename it to cgroup_reclaim().

[ After all, "global reclaim" is just regular reclaim invoked from the
  page allocator. It's reclaim on behalf of a cgroup limit that is a
  special case of reclaim, and should be explicit - not the reverse. ]

sane_reclaim() isn't very descriptive either: it tests whether we can use
the regular writeback throttling - available during regular page reclaim
or cgroup2 limit reclaim - or need to use the broken
wait_on_page_writeback() method.  Use "writeback_throttling_sane()".

Link: http://lkml.kernel.org/r/20191022144803.302233-5-hannes@cmpxchg.org


Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Reviewed-by: default avatarRoman Gushchin <guro@fb.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a1086291

mm/vmscan.c

+18 −20
Original line number Diff line number Diff line
@@ -239,13 +239,13 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker) 
	up_write(&shrinker_rwsem);

}



static bool global_reclaim(struct scan_control *sc)

static bool cgroup_reclaim(struct scan_control *sc)

{

	return !sc->target_mem_cgroup;

	return sc->target_mem_cgroup;

}



/**

 * sane_reclaim - is the usual dirty throttling mechanism operational?

 * writeback_throttling_sane - is the usual dirty throttling mechanism available?

 * @sc: scan_control in question

 *

 * The normal page dirty throttling mechanism in balance_dirty_pages() is
@@ -257,11 +257,9 @@ static bool global_reclaim(struct scan_control *sc) 
 * This function tests whether the vmscan currently in progress can assume

 * that the normal dirty throttling mechanism is operational.

 */

static bool sane_reclaim(struct scan_control *sc)

static bool writeback_throttling_sane(struct scan_control *sc)

{

	struct mem_cgroup *memcg = sc->target_mem_cgroup;



	if (!memcg)

	if (!cgroup_reclaim(sc))

		return true;

#ifdef CONFIG_CGROUP_WRITEBACK

	if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
@@ -302,12 +300,12 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker) 
{

}



static bool global_reclaim(struct scan_control *sc)

static bool cgroup_reclaim(struct scan_control *sc)

{

	return true;

	return false;

}



static bool sane_reclaim(struct scan_control *sc)

static bool writeback_throttling_sane(struct scan_control *sc)

{

	return true;

}
@@ -1227,7 +1225,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, 
				goto activate_locked;



			/* Case 2 above */

			} else if (sane_reclaim(sc) ||

			} else if (writeback_throttling_sane(sc) ||

			    !PageReclaim(page) || !may_enter_fs) {

				/*

				 * This is slightly racy - end_page_writeback()
@@ -1821,7 +1819,7 @@ static int too_many_isolated(struct pglist_data *pgdat, int file, 
	if (current_is_kswapd())

		return 0;



	if (!sane_reclaim(sc))

	if (!writeback_throttling_sane(sc))

		return 0;



	if (file) {
@@ -1971,7 +1969,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, 
	reclaim_stat->recent_scanned[file] += nr_taken;



	item = current_is_kswapd() ? PGSCAN_KSWAPD : PGSCAN_DIRECT;

	if (global_reclaim(sc))

	if (!cgroup_reclaim(sc))

		__count_vm_events(item, nr_scanned);

	__count_memcg_events(lruvec_memcg(lruvec), item, nr_scanned);

	spin_unlock_irq(&pgdat->lru_lock);
@@ -1985,7 +1983,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, 
	spin_lock_irq(&pgdat->lru_lock);



	item = current_is_kswapd() ? PGSTEAL_KSWAPD : PGSTEAL_DIRECT;

	if (global_reclaim(sc))

	if (!cgroup_reclaim(sc))

		__count_vm_events(item, nr_reclaimed);

	__count_memcg_events(lruvec_memcg(lruvec), item, nr_reclaimed);

	reclaim_stat->recent_rotated[0] += stat.nr_activate[0];
@@ -2309,7 +2307,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg, 
	 * using the memory controller's swap limit feature would be

	 * too expensive.

	 */

	if (!global_reclaim(sc) && !swappiness) {

	if (cgroup_reclaim(sc) && !swappiness) {

		scan_balance = SCAN_FILE;

		goto out;

	}
@@ -2333,7 +2331,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg, 
	 * thrashing file LRU becomes infinitely more attractive than

	 * anon pages.  Try to detect this based on file LRU size.

	 */

	if (global_reclaim(sc)) {

	if (!cgroup_reclaim(sc)) {

		unsigned long pgdatfile;

		unsigned long pgdatfree;

		int z;
@@ -2564,7 +2562,7 @@ static void shrink_node_memcg(struct pglist_data *pgdat, struct mem_cgroup *memc 
	 * abort proportional reclaim if either the file or anon lru has already

	 * dropped to zero at the first pass.

	 */

	scan_adjusted = (global_reclaim(sc) && !current_is_kswapd() &&

	scan_adjusted = (!cgroup_reclaim(sc) && !current_is_kswapd() &&

			 sc->priority == DEF_PRIORITY);



	blk_start_plug(&plug);
@@ -2853,7 +2851,7 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc) 
		 * Legacy memcg will stall in page writeback so avoid forcibly

		 * stalling in wait_iff_congested().

		 */

		if (!global_reclaim(sc) && sane_reclaim(sc) &&

		if (cgroup_reclaim(sc) && writeback_throttling_sane(sc) &&

		    sc->nr.dirty && sc->nr.dirty == sc->nr.congested)

			set_memcg_congestion(pgdat, root, true);
@@ -2948,7 +2946,7 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc) 
		 * Take care memory controller reclaiming has small influence

		 * to global LRU.

		 */

		if (global_reclaim(sc)) {

		if (!cgroup_reclaim(sc)) {

			if (!cpuset_zone_allowed(zone,

						 GFP_KERNEL | __GFP_HARDWALL))

				continue;
@@ -3048,7 +3046,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, 
retry:

	delayacct_freepages_start();



	if (global_reclaim(sc))

	if (!cgroup_reclaim(sc))

		__count_zid_vm_events(ALLOCSTALL, sc->reclaim_idx, 1);



	do {