On Thu, Feb 23, 2023 at 02:17:18PM -0400, Jason Gunthorpe wrote: > On Thu, Feb 23, 2023 at 08:15:17AM -1000, Tejun Heo wrote: > > 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. > > Isn't memfd also in the same boat? I see. Yeah, that's looks like named shared anon. The first one instantiating a page would always be the owner. Thanks. -- tejun
