Re: [PATCH v6 32/33] mm: memcontrol: eliminate the problem of dying memory cgroup for LRU folios

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

On 4/7/26 2:11 AM, Joshua Hahn wrote:
> On Thu,  5 Mar 2026 19:52:50 +0800 Qi Zheng <qi.zheng@linux.dev> wrote:
> 
>> From: Muchun Song <songmuchun@bytedance.com>
>>
>> Now that everything is set up, switch folio->memcg_data pointers to
>> objcgs, update the accessors, and execute reparenting on cgroup death.
>>
>> Finally, folio->memcg_data of LRU folios and kmem folios will always
>> point to an object cgroup pointer. The folio->memcg_data of slab
>> folios will point to an vector of object cgroups.
>>
>> Signed-off-by: Muchun Song <songmuchun@bytedance.com>
>> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
>> Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
>> ---
> 
> Hello Qi, thank you for this series!
> 
>>   static void memcg_online_kmem(struct mem_cgroup *memcg)
>> @@ -4949,16 +4985,20 @@ void mem_cgroup_calculate_protection(struct mem_cgroup *root,
>>   static int charge_memcg(struct folio *folio, struct mem_cgroup *memcg,
>>   			gfp_t gfp)
>>   {
>> -	int ret;
>> -
>> -	ret = try_charge(memcg, gfp, folio_nr_pages(folio));
> 
> While developing on top of mm-new I found that this was the last caller of
> try_charge(). I was thinking that it might be a nice opportunity to just

Yeah, we're already aware of this.

> remove the definition of try_charge() as well, maybe as a clean up patch
> at the end of the series.

Will send a separate cleanup patch later.

Thanks,
Qi