Re: [PATCH v2 0/2] mm/zswap: Fixes and improves the zswap global shrinker

[Hao Jia]

On 2026/7/23 12:49, Yosry Ahmed wrote:
> On Wed, Jul 22, 2026 at 6:21 PM Hao Jia <jiahao.kernel@xxxxxxxxx> wrote:
> > On 2026/7/20 09:26, Hao Jia wrote:
> > > On 2026/7/18 12:40, Andrew Morton wrote:
> > > > On Fri, 17 Jul 2026 18:28:04 -0700 Yosry Ahmed <yosry@xxxxxxxxxx> wrote:
> > > >
> > > > > > The [1/2] changelog lacks a description of how the flaw impacts users.
> > > > > > Please describe this fully and maintain that info within the
> > > > > > changelogging.  This info helps -stable maintainers and others
> > > > > > understand why we're proposing a backport and helps myself and others
> > > > > > with timing decisions.
> > > > >
> > > > > The first line in the changelog should be sufficient imo: "Zswap
> > > > > writeback on hitting the pool limit is broken when memory cgroup is
> > > > > disabled"
> > > >
> > > > "broken"?  Perhaps this means "fails to occur".
> > > >
> > > > But what is the userspace-visible impact?  IOW, why are we proposing a
> > > > backport?
> > >
> > > Perhaps the first paragraph of the commit1 message could be modified as
> > > follows? I have added a description of the issues that occur without
> > > this patch.
> >
> > Hi Andrew, Yosry, and Nhat,
> > Any thoughts on this change?
>
> I would front load the user impact in the first paragraph:
>
> Zswap writeback when the global pool limit is hit fails when memory
> cgroups are disabled. The pool remains full until it is organically
> drained by swapins or memory freeing, leading to zswap store failures
> and pages bypassing getting written directly to the backing swap device,
> causing LRU inversion (hotter pages with higher fault latency).
>
> ...

Will done.

Thanks,
Hao