Re: [PATCH] mm/memcontrol: respect zswap.writeback setting from parent cg too

[Nhat Pham <nphamcs@gmail.com>]

On Thu, Aug 15, 2024 at 3:10 PM Yosry Ahmed <yosryahmed@google.com> wrote:
>
> On Thu, Aug 15, 2024 at 3:08 PM Andrew Morton <akpm@linux-foundation.org> wrote:
> >
> > On Thu, 15 Aug 2024 12:12:26 -0700 Nhat Pham <nphamcs@gmail.com> wrote:
> >
> > > > Yeah, I thought about the other way around and reached the same
> > > > conclusion.
> > > > And there's permission boundary in the mix too - if root disables zswap
> > > > writeback for its cgroup, the subcgroups, which could possibly be owned
> > > > by other users, should not be able to reenable this.
> > >
> > > Hmm yeah, I think I agree with your and Yosry's reasonings :) It
> > > doesn't affect our use case AFAICS, and the code looks solid to me,
> > > so:
> > >
> > > Reviewed-by: Nhat Pham <nphamcs@gmail.com>
> >
> > But you'd still like an update to Documentation/admin-guide/cgroup-v2.rst?
>
>
> Yeah I'd rather see a v2 with updated docs, and hopefully a selftest
> if the existing tests problem is resolved.

Ah yeah, I was thinking this could be done in a follow-up patch.

But yes, please - documentation. Preferably everything together as v2.

>
> Also, do we want a Fixes tag and to backport this so that current
> users get the new behavior ASAP?

Hmm, I wonder if it's more confusing for users to change the behavior
in older kernels.

(OTOH, if this already is what people expect, then yeah it's a good
idea to backport).