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 <guro@xxxxxx>
Acked-by: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Signed-off-by: Yang Shi <shy828301@xxxxxxxxx>
---
mm/vmscan.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7f3c00e76fd1..c0d04f242917 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)
{
@@ -199,8 +206,7 @@ static int expand_one_shrinker_info(struct mem_cgroup *memcg,
int nid;
for_each_node(nid) {
- old = rcu_dereference_protected(
- mem_cgroup_nodeinfo(memcg, nid)->shrinker_info, true);
+ old = shrinker_info_protected(memcg, nid);
/* Not yet online memcg */
if (!old)
return 0;
@@ -231,7 +237,7 @@ void free_shrinker_info(struct mem_cgroup *memcg)
for_each_node(nid) {
pn = mem_cgroup_nodeinfo(memcg, nid);
- info = rcu_dereference_protected(pn->shrinker_info, true);
+ info = shrinker_info_protected(memcg, nid);
kvfree(info);
rcu_assign_pointer(pn->shrinker_info, NULL);
}
@@ -674,8 +680,7 @@ 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
