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

[Qi Zheng <qi.zheng@linux.dev>]

On 1/18/26 11:22 AM, Shakeel Butt wrote:
> On Thu, Jan 15, 2026 at 06:41:38PM +0800, Qi Zheng wrote:
>> From: Qi Zheng <zhengqi.arch@bytedance.com>
>>
>> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
>> ---
>>   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.

It seems that lruvec_stats->state_local (non-hierarchical) needs to be
relocated in both v1 and 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
>>