Re: [RESEND PATCH] mm: bail out from partial cgroup_reclaim inside shrink_lruvec

[Zhaoyang Huang <huangzhaoyang@gmail.com>]

On Thu, Feb 12, 2026 at 6:13 AM T.J. Mercier <tjmercier@google.com> wrote:
>
> On Mon, Feb 9, 2026 at 9:44 PM zhaoyang.huang <zhaoyang.huang@unisoc.com> wrote:
> >
> > From: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
>
> Hi Zhaoyang,
>
> > Nowadays, ANDROID system replaces madivse with memory.reclaim to implement
> > user space memory management which desires to reclaim a certain amount of
> > memcg's memory. However, oversized reclaiming and high latency are observed
> > as there is no limitation over nr_reclaimed inside try_to_shrink_lruvec
> > when MGLRU enabled. Besides, this could also affect all none root_reclaim
> > such as reclaim_high etc.
> > The commit 'b82b530740b9' ("mm: vmscan: restore incremental cgroup
> > iteration") introduces sc->memcg_full_walk to limit the walk range of
> > mem_cgroup_iter. This commit would like to make single memcg's scanning
> > more precised by judging if nr_reclaimed reached when sc->memcg_full_walk
> > not set.
> >
> > Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
> > ---
> >  mm/vmscan.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index 670fe9fae5ba..03bda1094621 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -4832,8 +4832,8 @@ static bool should_abort_scan(struct lruvec *lruvec, struct scan_control *sc)
> >         int i;
> >         enum zone_watermarks mark;
> >
> > -       /* don't abort memcg reclaim to ensure fairness */
> > -       if (!root_reclaim(sc))
> > +       /* don't abort full walk memcg reclaim to ensure fairness */
> > +       if (!root_reclaim(sc) && sc->memcg_full_walk)
> >                 return false;
>
> Can't we just get rid of this if (!root_reclaim(sc)) check entirely
> now that commit 'b82b530740b9' ("mm: vmscan: restore incremental
> cgroup
> iteration") provides eventual fairness for the proactive reclaim case?
> That wasn't true when this check was added initially.
Thanks for the suggestion which works, I will resend the patch.
>
> Thanks,
> T.J.