Re: [PATCH v3 1/2] mm/zswap: Fix global shrinker when memory cgroup is disabled

[Andrew Morton]

On Thu, 30 Jul 2026 09:52:38 -0700 Yosry Ahmed <yosry@xxxxxxxxxx> wrote:

> > > >
> > > > How does this affect users?  What behavior do they observe when it
> > > > occurs?
> > >
> > > I think the first paragraph sums it up pretty well, especially the
> > > last sentence "hotter pages with higher fault latency".
> >
> > How do users observe that?
> >
> > See, what I'm looking for here is an explanation for why we're
> > proposing a backport.  How are our users harmed by the current code and
> > how does this change benefit them?
> 
> It's a potential performance regression when using zswap with memcg
> disabled. Sorry I just realized you were looking for a high level
> description not detailed symptoms :)

Are we able to guess how significant this is?  It should have
significant impact to justify a backport.

Sorry to push - I'm forever trying to train people to describe the
userspace-visible effects so we can make these backporting decisions!

And to justify those decisions to -stable maintainers

And so that someone who is experiencing a slowdown in some private
kernel branch can look at the changelog and decide whether this might
fix it for them.