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From:   Joonsoo Kim <js1304@gmail.com>
Date:   Thu, 9 Apr 2020 09:53:59 +0900
Message-ID: <CAAmzW4MANwv6OS646Tkbvs1Db+kn6f2=WDJHi9EAXsz0vp1sXA@mail.gmail.com>
Subject: Re: [PATCH v5 05/10] mm/swap: charge the page when adding to the swap cache
To:     Hillf Danton <hdanton@sina.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Michal Hocko <mhocko@kernel.org>,
        Hugh Dickins <hughd@google.com>,
        Minchan Kim <minchan@kernel.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Mel Gorman <mgorman@techsingularity.net>
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2020=EB=85=84 4=EC=9B=94 7=EC=9D=BC (=ED=99=94) =EC=98=A4=EC=A0=84 11:21, H=
illf Danton <hdanton@sina.com>=EB=8B=98=EC=9D=B4 =EC=9E=91=EC=84=B1:
>
>
> On Tue, 7 Apr 2020 09:42:54 +0900 Joonsoo Kim wrote:
> >
> > 2020=3DEB=3D85=3D84 4=3DEC=3D9B=3D94 6=3DEC=3D9D=3DBC (=3DEC=3D9B=3D94)=
 =3DEC=3D98=3DA4=3DED=3D9B=3D84 8:58, Hi=3D
> > llf Danton <hdanton@sina.com>=3DEB=3D8B=3D98=3DEC=3D9D=3DB4 =3DEC=3D9E=
=3D91=3DEC=3D84=3DB1:
> > >
> > >
> > > On Fri,  3 Apr 2020 14:40:43 +0900 Joonsoo Kim wrote:
> > > >
> > > > @@ -153,11 +165,16 @@ int add_to_swap_cache(struct page *page, swp_=
entr=3D
> > y_t entry,
> > > >               xas_unlock_irq(&xas);
> > > >       } while (xas_nomem(&xas, gfp));
> > > >
> > > > -     if (!xas_error(&xas))
> > > > +     if (!xas_error(&xas)) {
> > > > +             mem_cgroup_commit_charge(page, memcg, false, compound=
);
> > >
> > > Add a tp
> > >                 trace_mm_add_to_swap_cache(page);
> >
> > Please let me know the reason of this comment.
>
> It is derived from
>
>         trace_mm_filemap_add_to_page_cache(page);
>
> in __add_to_page_cache_locked().

Maybe, it has it's own purpose and it would not be applied here. If
someone want to add
a tp here, it can be done with a justification, after this patchset.

Thanks.