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From:   Zhaoyang Huang <huangzhaoyang@gmail.com>
Date:   Thu, 25 May 2023 09:23:07 +0800
Message-ID: <CAGWkznGs=voCMYWsSRMJ7ZKxz0NcB6P9ynOK8AizHBHZG2MoDA@mail.gmail.com>
Subject: Re: [PATCH] mm: deduct the number of pages reclaimed by madvise from workingset
To:     Suren Baghdasaryan <surenb@google.com>
Cc:     "zhaoyang.huang" <zhaoyang.huang@unisoc.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, ke.wang@unisoc.com
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On Thu, May 25, 2023 at 4:41=E2=80=AFAM Suren Baghdasaryan <surenb@google.c=
om> wrote:
>
> On Wed, May 24, 2023 at 2:13=E2=80=AFAM zhaoyang.huang
> <zhaoyang.huang@unisoc.com> wrote:
> >
> > From: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
> >
> > The pages reclaimed by madvise_pageout are made of inactive and dropped=
 from LRU
> > forcefully, which lead to the coming up refault pages possess a large r=
efault
> > distance than it should be. These could affect the accuracy of thrashin=
g when
> > madvise_pageout is used as a common way of memory reclaiming as ANDROID=
 does now.
>
> Doesn't workingset_eviction() in the following call chain already
> handle nonresident page aging?:
>
> reclaim_pages
>   reclaim_folio_list
>     shrink_folio_list
>       __remove_mapping
>         workingset_eviction
>           workingset_age_nonresident
Yes. What I suggest is to minor this pages from non-resident as they
are dropped forcefully
>
>
> >
> > Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
> > ---
> >  include/linux/swap.h | 2 +-
> >  mm/madvise.c         | 4 ++--
> >  mm/vmscan.c          | 8 +++++++-
> >  3 files changed, 10 insertions(+), 4 deletions(-)
> >
> > diff --git a/include/linux/swap.h b/include/linux/swap.h
> > index 2787b84..0312142 100644
> > --- a/include/linux/swap.h
> > +++ b/include/linux/swap.h
> > @@ -428,7 +428,7 @@ extern unsigned long mem_cgroup_shrink_node(struct =
mem_cgroup *mem,
> >  extern int vm_swappiness;
> >  long remove_mapping(struct address_space *mapping, struct folio *folio=
);
> >
> > -extern unsigned long reclaim_pages(struct list_head *page_list);
> > +extern unsigned long reclaim_pages(struct mm_struct *mm, struct list_h=
ead *page_list);
> >  #ifdef CONFIG_NUMA
> >  extern int node_reclaim_mode;
> >  extern int sysctl_min_unmapped_ratio;
> > diff --git a/mm/madvise.c b/mm/madvise.c
> > index b6ea204..61c8d7b 100644
> > --- a/mm/madvise.c
> > +++ b/mm/madvise.c
> > @@ -420,7 +420,7 @@ static int madvise_cold_or_pageout_pte_range(pmd_t =
*pmd,
> >  huge_unlock:
> >                 spin_unlock(ptl);
> >                 if (pageout)
> > -                       reclaim_pages(&page_list);
> > +                       reclaim_pages(mm, &page_list);
> >                 return 0;
> >         }
> >
> > @@ -516,7 +516,7 @@ static int madvise_cold_or_pageout_pte_range(pmd_t =
*pmd,
> >         arch_leave_lazy_mmu_mode();
> >         pte_unmap_unlock(orig_pte, ptl);
> >         if (pageout)
> > -               reclaim_pages(&page_list);
> > +               reclaim_pages(mm, &page_list);
> >         cond_resched();
> >
> >         return 0;
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index 20facec..048c10b 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -2741,12 +2741,14 @@ static unsigned int reclaim_folio_list(struct l=
ist_head *folio_list,
> >         return nr_reclaimed;
> >  }
> >
> > -unsigned long reclaim_pages(struct list_head *folio_list)
> > +unsigned long reclaim_pages(struct mm_struct *mm, struct list_head *fo=
lio_list)
>
> You would also need to change Damon usage of reclaim_pages() here:
> https://elixir.bootlin.com/linux/v6.4-rc1/source/mm/damon/paddr.c#L253
ok, thanks for reminding
>
> >  {
> >         int nid;
> >         unsigned int nr_reclaimed =3D 0;
> >         LIST_HEAD(node_folio_list);
> >         unsigned int noreclaim_flag;
> > +       struct lruvec *lruvec;
> > +       struct mem_cgroup *memcg =3D get_mem_cgroup_from_mm(mm);
> >
> >         if (list_empty(folio_list))
> >                 return nr_reclaimed;
> > @@ -2764,10 +2766,14 @@ unsigned long reclaim_pages(struct list_head *f=
olio_list)
> >                 }
> >
> >                 nr_reclaimed +=3D reclaim_folio_list(&node_folio_list, =
NODE_DATA(nid));
> > +               lruvec =3D &memcg->nodeinfo[nid]->lruvec;
> > +               workingset_age_nonresident(lruvec, -nr_reclaimed);
> >                 nid =3D folio_nid(lru_to_folio(folio_list));
> >         } while (!list_empty(folio_list));
> >
> >         nr_reclaimed +=3D reclaim_folio_list(&node_folio_list, NODE_DAT=
A(nid));
> > +       lruvec =3D &memcg->nodeinfo[nid]->lruvec;
> > +       workingset_age_nonresident(lruvec, -nr_reclaimed);
> >
> >         memalloc_noreclaim_restore(noreclaim_flag);
> >
> > --
> > 1.9.1
> >