Re: [PATCH 6/8] mm/zsmalloc, zswap: Handle objcg charging and lifetime in zsmalloc

[Nhat Pham <nphamcs@gmail.com>]

On Wed, Mar 4, 2026 at 8:46 AM Yosry Ahmed <yosry@kernel.org> wrote:
>
> > > AFAICT the only zswap-specific part is the actual stat indexes, what
> > > if these are parameterized at the zsmalloc pool level? AFAICT zswap
> > > and zram will never share a pool.
> >
> > TBH, if we were to start from scratch, these should be zsmalloc
> > counters not zswap counters. Only zsmalloc knows about the memory
> > placement and real memory consumption (i.e taking into account
> > intra-slot wasted space) - this information is abstracted away from
> > all of the callers.
>
> I agree, but we cannot change the zswap stats now that we added them.
> Keep in mind that when they were added zsmalloc was not the only
> backend.
>
> > And if/when zram supports cgroup tracking, memory
> > used by zswap and memory used by zram is indistinguishable, no?
>
> It is distinguishable as long as they use different zsmalloc pools, I
> don't see why we'd need to share a pool.
>
> > Anyway, Joshua, do you think this is doable? Seems promising to me,
> > but idk if it will be clean to implement or not.
>
> Not sure what you mean here? Changing the stats to be zsmalloc-based?
> IIUC we can't do this without breaking userspace.

No I meant your proposal haha. Sorry for being confusing - probably
need more caffeine :)