Re: [PATCH 14/19] mm: Introduce a cgroup for pinned memory

[Tejun Heo]

On Thu, Feb 23, 2023 at 02:10:56PM -0400, Jason Gunthorpe wrote:
> > I am not familiar with memfd, but based on
> > mem_cgroup_swapin_charge_folio() it seems like if cgroup B swapped in
> > the pages they will remain charged to cgroup A, unless cgroup A is
> > removed/offlined. Am I missing something?
> 
> Ah, I don't know, Tejun said:
> 
> "but it can converge when page usage transfers across cgroups
> if needed."
> 
> Which I assumed was swap related but I don't know how convergence
> works.

That'd work for pagecache. For swap-backed, I think Yosry is right. Is
MAP_SHARED | MAP_ANONYMOUS a concern? Such mappings can only be shared
through forking, so it's not a common thing to be shared across different
resource domains.

Thanks.

-- 
tejun