mm: kmem: reimplement get_obj_cgroup_from_current()

Reimplement get_obj_cgroup_from_current() using current_obj_cgroup(). 
get_obj_cgroup_from_current() and current_obj_cgroup() share 80% of the
code, so the new implementation is almost trivial.

get_obj_cgroup_from_current() is a convenient function used by the
bpf subsystem, so there is no reason to get rid of it completely.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Roman Gushchin (Cruise) <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]>
Acked-by: Shakeel Butt <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Dennis Zhou <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Naresh Kamboju <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 10 insertions, 1 deletions

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 8006bc3bd7bf..b3d2e3e60eed 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1805,9 +1805,18 @@ void __memcg_kmem_uncharge_page(struct page *page, int order);
  * needs to be used outside of the local scope.
  */
 struct obj_cgroup *current_obj_cgroup(void);
-struct obj_cgroup *get_obj_cgroup_from_current(void);
 struct obj_cgroup *get_obj_cgroup_from_folio(struct folio *folio);
 
+static inline struct obj_cgroup *get_obj_cgroup_from_current(void)
+{
+	struct obj_cgroup *objcg = current_obj_cgroup();
+
+	if (objcg)
+		obj_cgroup_get(objcg);
+
+	return objcg;
+}
+
 int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size);
 void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size);