Commit aa50b501 authored by Kinsey Ho's avatar Kinsey Ho Committed by Andrew Morton
Browse files

mm: clean up mem_cgroup_iter() 

A clean up to make variable names more clear and to improve code
readability.

No functional change.

Link: https://lkml.kernel.org/r/20240905003058.1859929-6-kinseyho@google.com


Signed-off-by: default avatarKinsey Ho <kinseyho@google.com>
Reviewed-by: default avatarT.J. Mercier <tjmercier@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Tejun Heo <tj@kernel.org>
Cc: Yosry Ahmed <yosryahmed@google.com>
Cc: Zefan Li <lizefan.x@bytedance.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent ec0db74b

mm/memcontrol.c

+12 −20
Original line number Diff line number Diff line
@@ -987,8 +987,8 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root, 
{

	struct mem_cgroup_reclaim_iter *iter;

	struct cgroup_subsys_state *css;

	struct mem_cgroup *memcg;

	struct mem_cgroup *pos = NULL;

	struct mem_cgroup *pos;

	struct mem_cgroup *next;



	if (mem_cgroup_disabled())

		return NULL;
@@ -998,14 +998,13 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root, 


	rcu_read_lock();

restart:

	memcg = NULL;

	next = NULL;



	if (reclaim) {

		int gen;

		struct mem_cgroup_per_node *mz;

		int nid = reclaim->pgdat->node_id;



		mz = root->nodeinfo[reclaim->pgdat->node_id];

		iter = &mz->iter;

		iter = &root->nodeinfo[nid]->iter;

		gen = atomic_read(&iter->generation);



		/*
@@ -1018,29 +1017,22 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root, 
			goto out_unlock;



		pos = READ_ONCE(iter->position);

	} else if (prev) {

	} else

		pos = prev;

	}



	css = pos ? &pos->css : NULL;



	for (;;) {

		css = css_next_descendant_pre(css, &root->css);

		if (!css) {

			break;

		}



	while ((css = css_next_descendant_pre(css, &root->css))) {

		/*

		 * Verify the css and acquire a reference.  The root

		 * is provided by the caller, so we know it's alive

		 * and kicking, and don't take an extra reference.

		 */

		if (css == &root->css || css_tryget(css)) {

		if (css == &root->css || css_tryget(css))

			break;

	}

	}



	memcg = mem_cgroup_from_css(css);

	next = mem_cgroup_from_css(css);



	if (reclaim) {

		/*
@@ -1048,13 +1040,13 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root, 
		 * thread, so check that the value hasn't changed since we read

		 * it to avoid reclaiming from the same cgroup twice.

		 */

		if (cmpxchg(&iter->position, pos, memcg) != pos) {

		if (cmpxchg(&iter->position, pos, next) != pos) {

			if (css && css != &root->css)

				css_put(css);

			goto restart;

		}



		if (!memcg) {

		if (!next) {

			atomic_inc(&iter->generation);



			/*
@@ -1073,7 +1065,7 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root, 
	if (prev && prev != root)

		css_put(&prev->css);



	return memcg;

	return next;

}



/**