From 468ab8437a97a953895856c3709e48b3067da13c Mon Sep 17 00:00:00 2001 From: Yang Shi Date: Tue, 4 May 2021 18:36:26 -0700 Subject: [PATCH] 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: Yang Shi Acked-by: Roman Gushchin Acked-by: Kirill Tkhai Acked-by: Vlastimil Babka Reviewed-by: Shakeel Butt Cc: Dave Chinner Cc: Johannes Weiner Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 518084c..400f4a6 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -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; -- 2.7.4