From: Shakeel Butt <shakeel.butt@linux.dev>
Date: Thu, 25 Dec 2025 23:21:15 +0000 (-0800)
Subject: memcg: remove unused mem_cgroup_id() and mem_cgroup_from_id()
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2202e3a8cb80da583670034ee33c995513708949;p=thirdparty%2Fkernel%2Fstable.git

memcg: remove unused mem_cgroup_id() and mem_cgroup_from_id()

Now that all callers have been converted to use either:
 - The private ID APIs (mem_cgroup_private_id/mem_cgroup_from_private_id)
   for internal kernel objects that outlive their cgroup
 - The public cgroup ID APIs (mem_cgroup_ino/mem_cgroup_get_from_ino)
   for external interfaces

Remove the unused wrapper functions mem_cgroup_id() and
mem_cgroup_from_id() along with their !CONFIG_MEMCG stubs.

Link: https://lkml.kernel.org/r/20251225232116.294540-8-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: SeongJae Park <sj@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index c823150ec288..3e7d69020b39 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -830,12 +830,6 @@ static inline unsigned short mem_cgroup_private_id(struct mem_cgroup *memcg)
 }
 struct mem_cgroup *mem_cgroup_from_private_id(unsigned short id);
 
-static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg)
-{
-	return mem_cgroup_private_id(memcg);
-}
-struct mem_cgroup *mem_cgroup_from_id(unsigned short id);
-
 static inline u64 mem_cgroup_ino(struct mem_cgroup *memcg)
 {
 	return memcg ? cgroup_id(memcg->css.cgroup) : 0;
@@ -1282,18 +1276,6 @@ static inline void mem_cgroup_scan_tasks(struct mem_cgroup *memcg,
 {
 }
 
-static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg)
-{
-	return 0;
-}
-
-static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
-{
-	WARN_ON_ONCE(id);
-	/* XXX: This should always return root_mem_cgroup */
-	return NULL;
-}
-
 static inline unsigned short mem_cgroup_private_id(struct mem_cgroup *memcg)
 {
 	return 0;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 1ff2f9bd820c..ede39dde05df 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3615,11 +3615,6 @@ struct mem_cgroup *mem_cgroup_from_private_id(unsigned short id)
 	return xa_load(&mem_cgroup_private_ids, id);
 }
 
-struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
-{
-	return mem_cgroup_from_private_id(id);
-}
-
 struct mem_cgroup *mem_cgroup_get_from_ino(u64 ino)
 {
 	struct cgroup *cgrp;