Commit 7a704474 authored by Yosry Ahmed's avatar Yosry Ahmed Committed by Andrew Morton
Browse files

mm: memcg: rename and document global_reclaim() 

Evidently, global_reclaim() can be a confusing name.  Especially that it
used to exist before with a subtly different definition (removed by commit
b5ead35e ("mm: vmscan: naming fixes: global_reclaim() and
sane_reclaim()").  It can be interpreted as non-cgroup reclaim, even
though it returns true for cgroup reclaim on the root memcg (through
memory.reclaim).

Rename it to root_reclaim() in an attempt to make it less ambiguous, and
add documentation to it as well as cgroup_reclaim.

Link: https://lkml.kernel.org/r/20230621023053.432374-1-yosryahmed@google.com


Signed-off-by: default avatarYosry Ahmed <yosryahmed@google.com>
Reported-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Closes: https://lore.kernel.org/lkml/20230405200150.GA35884@cmpxchg.org/


Acked-by: default avatarYu Zhao <yuzhao@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 7302338a

mm/vmscan.c

+13 −8
Original line number Diff line number Diff line
@@ -429,12 +429,17 @@ void reparent_shrinker_deferred(struct mem_cgroup *memcg) 
	up_read(&shrinker_rwsem);

}



/* Returns true for reclaim through cgroup limits or cgroup interfaces. */

static bool cgroup_reclaim(struct scan_control *sc)

{

	return sc->target_mem_cgroup;

}



static bool global_reclaim(struct scan_control *sc)

/*

 * Returns true for reclaim on the root cgroup. This is true for direct

 * allocator reclaim and reclaim through cgroup interfaces on the root cgroup.

 */

static bool root_reclaim(struct scan_control *sc)

{

	return !sc->target_mem_cgroup || mem_cgroup_is_root(sc->target_mem_cgroup);

}
@@ -489,7 +494,7 @@ static bool cgroup_reclaim(struct scan_control *sc) 
	return false;

}



static bool global_reclaim(struct scan_control *sc)

static bool root_reclaim(struct scan_control *sc)

{

	return true;

}
@@ -546,7 +551,7 @@ static void flush_reclaim_state(struct scan_control *sc) 
	 * memcg reclaim, to make reporting more accurate and reduce

	 * underestimation, but it's probably not worth the complexity for now.

	 */

	if (current->reclaim_state && global_reclaim(sc)) {

	if (current->reclaim_state && root_reclaim(sc)) {

		sc->nr_reclaimed += current->reclaim_state->reclaimed;

		current->reclaim_state->reclaimed = 0;

	}
@@ -5325,7 +5330,7 @@ static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc, bool 
static unsigned long get_nr_to_reclaim(struct scan_control *sc)

{

	/* don't abort memcg reclaim to ensure fairness */

	if (!global_reclaim(sc))

	if (!root_reclaim(sc))

		return -1;



	return max(sc->nr_to_reclaim, compact_gap(sc->order));
@@ -5477,7 +5482,7 @@ static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc 
{

	struct blk_plug plug;



	VM_WARN_ON_ONCE(global_reclaim(sc));

	VM_WARN_ON_ONCE(root_reclaim(sc));

	VM_WARN_ON_ONCE(!sc->may_writepage || !sc->may_unmap);



	lru_add_drain();
@@ -5538,7 +5543,7 @@ static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control * 
	struct blk_plug plug;

	unsigned long reclaimed = sc->nr_reclaimed;



	VM_WARN_ON_ONCE(!global_reclaim(sc));

	VM_WARN_ON_ONCE(!root_reclaim(sc));



	/*

	 * Unmapped clean folios are already prioritized. Scanning for more of
@@ -6260,7 +6265,7 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) 
	bool proportional_reclaim;

	struct blk_plug plug;



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

	if (lru_gen_enabled() && !root_reclaim(sc)) {

		lru_gen_shrink_lruvec(lruvec, sc);

		return;

	}
@@ -6501,7 +6506,7 @@ static void shrink_node(pg_data_t *pgdat, struct scan_control *sc) 
	struct lruvec *target_lruvec;

	bool reclaimable = false;



	if (lru_gen_enabled() && global_reclaim(sc)) {

	if (lru_gen_enabled() && root_reclaim(sc)) {

		lru_gen_shrink_node(pgdat, sc);

		return;

	}