Re: [PATCH v3] mm: mglru: fix stale batch updates after memcg reparenting

[Qi Zheng]

On 6/26/26 5:39 PM, Johannes Weiner wrote:
> On Fri, Jun 26, 2026 at 03:04:17PM +0800, Qi Zheng wrote:
> > On 6/26/26 2:48 PM, Harry Yoo wrote:
> > > On 6/26/26 3:24 PM, Qi Zheng wrote:
> > > > On 6/26/26 12:59 PM, Harry Yoo wrote:
> > > > > Observing a dying cgroup should be rare anyway, it's worth focusing
> > > > > more on readability?
> > > >
> > > > While it's rare to encounter consecutive dying memcgs, it can still
> > > > happen, right?
> > >
> > > But is worth saving a few instruction in a basic block that is
> > > unlikely() to be executed?
> >
> > I don't have a strong opinion here. Hi Johannes, I'll leave the decision
> > up to you. If necessary, I can send out the v4.
>
> Yes, I was thinking what Harry actually bothered to spell out ;)
>
> The race is rare, multiple levels even rarer, and even *then*
> mem_cgroup_lruvec() is a quick inline.
>
> This way you have one block to handle that one rare race
> condition. One place to put the comment. No labels, no goto.
>
> Simplicity wins :)

Okay, I will update it as you suggested and send out the v4.

Hi Shakeel, do we really need to move lock_batch_lruvec() to
memcontrol.h? It's currently only used by reset_batch_size().

Thanks,
Qi