linux-kernel - Re: [PATCH 2/5] mm/sparse: free section usage memory in case populate_section

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Message-ID: <CAA+hA=TQ6ZzJcBkBju2OyxNGhUHSnm-MHED5GTzsYECKh2PEzA@mail.gmail.com>
Date:   Tue, 25 May 2021 16:15:59 +0800
From:   Dong Aisheng <dongas86@...il.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     Dong Aisheng <aisheng.dong@....com>, linux-mm@...ck.org,
        open list <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 2/5] mm/sparse: free section usage memory in case
 populate_section_memmap failed

On Tue, May 25, 2021 at 3:52 PM David Hildenbrand <david@...hat.com> wrote:
>
> On 17.05.21 13:20, Dong Aisheng wrote:
> > Free section usage memory in case populate_section_memmap failed.
> > We use map_count to track the remain unused memory to be freed.
> >
> > Cc: Andrew Morton <akpm@...ux-foundation.org>
> > Signed-off-by: Dong Aisheng <aisheng.dong@....com>
> > ---
> >   mm/sparse.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/mm/sparse.c b/mm/sparse.c
> > index 7ac481353b6b..98bfacc763da 100644
> > --- a/mm/sparse.c
> > +++ b/mm/sparse.c
> > @@ -549,12 +549,14 @@ static void __init sparse_init_nid(int nid, unsigned long pnum_begin,
> >                              __func__, nid);
> >                       pnum_begin = pnum;
> >                       sparse_buffer_fini();
> > +                     memblock_free_early(__pa(usage), map_count * mem_section_usage_size());
> >                       goto failed;
> >               }
> >               check_usemap_section_nr(nid, usage);
> >               sparse_init_one_section(__nr_to_section(pnum), pnum, map, usage,
> >                               SECTION_IS_EARLY);
> >               usage = (void *) usage + mem_section_usage_size();
> > +             map_count--;
> >       }
> >       sparse_buffer_fini();
> >       return;
> >
>
> Why care about optimizing something that literally never fails, and if
> it would fail, leave the system in a sub-optimal, mostly unusable state?
>

It just fixes the code logic.
I'm going to listen to more comments, if everyone thinks it's not needed.
I may drop in V2.

Regards
Aisheng

> --
> Thanks,
>
> David / dhildenb
>