Re: [PATCH v5 update 30/32] mm: memcontrol: convert objcg to be per-memcg per-node type

[Qi Zheng]

On 2/27/26 4:05 AM, Shakeel Butt wrote:
> On Wed, Feb 25, 2026 at 05:44:56PM +0800, Qi Zheng wrote:
> > From: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
> >
> > Convert objcg to be per-memcg per-node type, so that when reparent LRU
> > folios later, we can hold the lru lock at the node level, thus avoiding
> > holding too many lru locks at once.
> >
> > Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
> > ---
> > changlog:
> >   - fix a missing root_obj_cgroup conversion and completely delete
> >     root_obj_cgroup.
>
> After this patch, do we care that page/folio/slab points to the objcg of the
> same node as them for a given memcg?

Maybe not. My only concern is whether the kernel has a way of
determining whether two folios belong to the same memcg by checking if
the objcg pointers are equal. If so, it needs to be changed to check if
objcg->memcg are equal.

>