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. Acked-by: Roman Gushchin <[email protected]> Acked-by: Kirill Tkhai <[email protected]> Acked-by: Vlastimil Babka <[email protected]> Reviewed-by: Shakeel Butt <[email protected]> Signed-off-by: Yang Shi <[email protected]> --- mm/vmscan.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 7fdfdacf9a1f..ef9f1531a6ee 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; @@ -232,7 +239,7 @@ void free_shrinker_info(struct mem_cgroup *memcg) for_each_node(nid) { pn = memcg->nodeinfo[nid]; - info = rcu_dereference_protected(pn->shrinker_info, true); + info = shrinker_info_protected(memcg, nid); kvfree(info); rcu_assign_pointer(pn->shrinker_info, NULL); } @@ -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; -- 2.26.2
