Commit 468ab843 authored by Yang Shi's avatar Yang Shi Committed by Linus Torvalds
Browse files

mm: vmscan: add shrinker_info_protected() helper 

The shrinker_info is dereferenced in a couple of places via
rcu_dereference_protected with different calling conventions, for
example, using mem_cgroup_nodeinfo helper or dereferencing
memcg->nodeinfo[nid]->shrinker_info.  And the later patch will add more
dereference places.

So extract the dereference into a helper to make the code more readable.
No functional change.

[akpm@linux-foundation.org: retain rcu_dereference_protected() in free_shrinker_info(), per Hugh]

Link: https://lkml.kernel.org/r/20210311190845.9708-8-shy828301@gmail.com


Signed-off-by: default avatarYang Shi <shy828301@gmail.com>
Acked-by: default avatarRoman Gushchin <guro@fb.com>
Acked-by: default avatarKirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Reviewed-by: default avatarShakeel Butt <shakeelb@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal 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 e4262c4f

mm/vmscan.c

+9 −3
Original line number Diff line number Diff line
@@ -192,6 +192,13 @@ static inline int shrinker_map_size(int nr_items) 
	return (DIV_ROUND_UP(nr_items, BITS_PER_LONG) * sizeof(unsigned long));

}



static struct shrinker_info *shrinker_info_protected(struct mem_cgroup *memcg,

						     int nid)

{

	return rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_info,

					 lockdep_is_held(&shrinker_rwsem));

}



static int expand_one_shrinker_info(struct mem_cgroup *memcg,

				    int size, int old_size)

{
@@ -201,7 +208,7 @@ static int expand_one_shrinker_info(struct mem_cgroup *memcg, 


	for_each_node(nid) {

		pn = memcg->nodeinfo[nid];

		old = rcu_dereference_protected(pn->shrinker_info, true);

		old = shrinker_info_protected(memcg, nid);

		/* Not yet online memcg */

		if (!old)

			return 0;
@@ -675,8 +682,7 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid, 
	if (!down_read_trylock(&shrinker_rwsem))

		return 0;



	info = rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_info,

					 true);

	info = shrinker_info_protected(memcg, nid);

	if (unlikely(!info))

		goto unlock;