Commit 131adcc7 authored Mar 05, 2026 by Qi Zheng Committed by Andrew Morton Apr 18, 2026

mm: memcontrol: refactor memcg_reparent_objcgs()

Refactor the memcg_reparent_objcgs() to facilitate subsequent reparenting
LRU folios here.

Link: https://lore.kernel.org/2e5696db1993e593a51004c1dacedbc261689629.1772711148.git.zhengqi.arch@bytedance.com


Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Cc: Allen Pais <apais@linux.microsoft.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Imran Khan <imran.f.khan@oracle.com>
Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yosry Ahmed <yosry@kernel.org>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

parent f3046526

mm/memcontrol.c

+24 −5

Original line number	Diff line number	Diff line
		@@ -208,15 +208,12 @@ static struct obj_cgroup *obj_cgroup_alloc(void)
		return objcg;
		}

		static void memcg_reparent_objcgs(struct mem_cgroup *memcg)
		static inline struct obj_cgroup __memcg_reparent_objcgs(struct mem_cgroup memcg,
		struct mem_cgroup *parent)
		{
		struct obj_cgroup objcg, iter;
		struct mem_cgroup *parent = parent_mem_cgroup(memcg);

		objcg = rcu_replace_pointer(memcg->objcg, NULL, true);

		spin_lock_irq(&objcg_lock);

		/* 1) Ready to reparent active objcg. */
		list_add(&objcg->list, &memcg->objcg_list);
		/* 2) Reparent active objcg and already reparented objcgs to parent. */
		@@ -225,7 +222,29 @@ static void memcg_reparent_objcgs(struct mem_cgroup *memcg)
		/* 3) Move already reparented objcgs to the parent's list */
		list_splice(&memcg->objcg_list, &parent->objcg_list);

		return objcg;
		}

		static inline void reparent_locks(struct mem_cgroup memcg, struct mem_cgroup parent)
		{
		spin_lock_irq(&objcg_lock);
		}

		static inline void reparent_unlocks(struct mem_cgroup memcg, struct mem_cgroup parent)
		{
		spin_unlock_irq(&objcg_lock);
		}

		static void memcg_reparent_objcgs(struct mem_cgroup *memcg)
		{
		struct obj_cgroup *objcg;
		struct mem_cgroup *parent = parent_mem_cgroup(memcg);

		reparent_locks(memcg, parent);

		objcg = __memcg_reparent_objcgs(memcg, parent);

		reparent_unlocks(memcg, parent);

		percpu_ref_kill(&objcg->refcnt);
		}