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

[Qi Zheng]

On 4/7/26 2:11 AM, Joshua Hahn wrote:
> On Thu,  5 Mar 2026 19:52:50 +0800 Qi Zheng <qi.zheng@xxxxxxxxx> wrote:
>
> > From: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> >
> > 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@xxxxxxxxxxxxx>
> > Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
> > Acked-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
> > ---
>
> 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