Re: [PATCH v3 28/30 fix 1/2] mm: memcontrol: fix lruvec_stats->state_local reparenting

[Shakeel Butt]

On Thu, Jan 15, 2026 at 06:41:38PM +0800, Qi Zheng wrote:
> From: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
> 
> Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
> ---
>  include/linux/memcontrol.h |  2 --
>  mm/memcontrol-v1.c         |  8 --------
>  mm/memcontrol-v1.h         |  5 ++++-
>  mm/memcontrol.c            | 19 ++++++++-----------
>  4 files changed, 12 insertions(+), 22 deletions(-)
> 
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 1fe554eec1e25..e0b84b109b7ac 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -944,8 +944,6 @@ bool memcg_vm_event_item_valid(enum vm_event_item idx);
>  unsigned long lruvec_page_state(struct lruvec *lruvec, enum node_stat_item idx);
>  unsigned long lruvec_page_state_local(struct lruvec *lruvec,
>  				      enum node_stat_item idx);
> -void reparent_memcg_lruvec_state_local(struct mem_cgroup *memcg,
> -				       struct mem_cgroup *parent, int idx);
>  
>  void mem_cgroup_flush_stats(struct mem_cgroup *memcg);
>  void mem_cgroup_flush_stats_ratelimited(struct mem_cgroup *memcg);
> diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c
> index 03b924920d6a5..daf9bad8c45ea 100644
> --- a/mm/memcontrol-v1.c
> +++ b/mm/memcontrol-v1.c
> @@ -1909,14 +1909,6 @@ void reparent_memcg1_state_local(struct mem_cgroup *memcg, struct mem_cgroup *pa
>  		reparent_memcg_state_local(memcg, parent, memcg1_stats[i]);
>  }
>  
> -void reparent_memcg1_lruvec_state_local(struct mem_cgroup *memcg, struct mem_cgroup *parent)
> -{
> -	int i;
> -
> -	for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++)
> -		reparent_memcg_lruvec_state_local(memcg, parent, memcg1_stats[i]);
> -}
> -
>  void memcg1_stat_format(struct mem_cgroup *memcg, struct seq_buf *s)
>  {
>  	unsigned long memory, memsw;
> diff --git a/mm/memcontrol-v1.h b/mm/memcontrol-v1.h
> index 45528195d3578..5b1188f3d4173 100644
> --- a/mm/memcontrol-v1.h
> +++ b/mm/memcontrol-v1.h
> @@ -75,7 +75,6 @@ void memcg1_uncharge_batch(struct mem_cgroup *memcg, unsigned long pgpgout,
>  
>  void memcg1_stat_format(struct mem_cgroup *memcg, struct seq_buf *s);
>  void reparent_memcg1_state_local(struct mem_cgroup *memcg, struct mem_cgroup *parent);
> -void reparent_memcg1_lruvec_state_local(struct mem_cgroup *memcg, struct mem_cgroup *parent);
>  
>  void memcg1_account_kmem(struct mem_cgroup *memcg, int nr_pages);
>  static inline bool memcg1_tcpmem_active(struct mem_cgroup *memcg)
> @@ -116,6 +115,10 @@ static inline void memcg1_uncharge_batch(struct mem_cgroup *memcg,
>  
>  static inline void memcg1_stat_format(struct mem_cgroup *memcg, struct seq_buf *s) {}
>  
> +static inline void reparent_memcg1_state_local(struct mem_cgroup *memcg, struct mem_cgroup *parent)
> +{
> +}
> +
>  static inline void memcg1_account_kmem(struct mem_cgroup *memcg, int nr_pages) {}
>  static inline bool memcg1_tcpmem_active(struct mem_cgroup *memcg) { return false; }
>  static inline bool memcg1_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages,
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 7333a37830051..b7b35143d4d2d 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -225,13 +225,13 @@ static inline struct obj_cgroup *__memcg_reparent_objcgs(struct mem_cgroup *memc
>  	return objcg;
>  }
>  
> -#ifdef CONFIG_MEMCG_V1
> +static void reparent_memcg_lruvec_state_local(struct mem_cgroup *memcg,
> +					      struct mem_cgroup *parent, int idx);
>  static void __mem_cgroup_flush_stats(struct mem_cgroup *memcg, bool force);
>  
>  static inline void reparent_state_local(struct mem_cgroup *memcg, struct mem_cgroup *parent)
>  {

No reparenting local stats for v2.

> -	if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
> -		return;
> +	int i;
>  
>  	synchronize_rcu();
>  
> @@ -239,13 +239,10 @@ static inline void reparent_state_local(struct mem_cgroup *memcg, struct mem_cgr
>  
>  	/* The following counts are all non-hierarchical and need to be reparented. */
>  	reparent_memcg1_state_local(memcg, parent);
> -	reparent_memcg1_lruvec_state_local(memcg, parent);
> -}
> -#else
> -static inline void reparent_state_local(struct mem_cgroup *memcg, struct mem_cgroup *parent)
> -{
> +
> +	for (i = 0; i < NR_LRU_LISTS; i++)
> +		reparent_memcg_lruvec_state_local(memcg, parent, i);
>  }
> -#endif
>  
>  static inline void reparent_locks(struct mem_cgroup *memcg, struct mem_cgroup *parent)
>  {
> @@ -510,8 +507,8 @@ unsigned long lruvec_page_state_local(struct lruvec *lruvec,
>  	return x;
>  }
>  
> -void reparent_memcg_lruvec_state_local(struct mem_cgroup *memcg,
> -				       struct mem_cgroup *parent, int idx)
> +static void reparent_memcg_lruvec_state_local(struct mem_cgroup *memcg,
> +					      struct mem_cgroup *parent, int idx)
>  {
>  	int i = memcg_stats_index(idx);
>  	int nid;
> -- 
> 2.20.1
>