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

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Date:   Tue, 18 May 2021 18:25:28 +0800
From:   Dong Aisheng <dongas86@...il.com>
To:     Mike Rapoport <rppt@...nel.org>
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 18, 2021 at 6:09 PM Mike Rapoport <rppt@...nel.org> wrote:
>
> On Mon, May 17, 2021 at 07:20:41PM +0800, 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());
>
> I'd move both sparse_buffer_fini() and freeing of 'usage' memory after the
> failed label.
>

Doing that needs to introduce another 'failed' label.
Do you think if it's necessary?

e.g.
diff --git a/mm/sparse.c b/mm/sparse.c
index 7ac481353b6b..408b737e168e 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -533,7 +533,7 @@ static void __init sparse_init_nid(int nid,
unsigned long pnum_begin,
                        mem_section_usage_size() * map_count);
        if (!usage) {
                pr_err("%s: node[%d] usemap allocation failed", __func__, nid);
-               goto failed;
+               goto failed1;
        }
        sparse_buffer_init(map_count * section_map_size(), nid);
        for_each_present_section_nr(pnum_begin, pnum) {
@@ -548,17 +548,20 @@ static void __init sparse_init_nid(int nid,
unsigned long pnum_begin,
                        pr_err("%s: node[%d] memory map backing
failed. Some memory will not be available.",
                               __func__, nid);
                        pnum_begin = pnum;
-                       sparse_buffer_fini();
-                       goto failed;
+                       goto failed2;
                }
                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;
-failed:
+failed2:
+       sparse_buffer_fini();
+       memblock_free_early(__pa(usage), map_count * mem_section_usage_size());
+failed1:
        /* We failed to allocate, mark all the following pnums as not present */
        for_each_present_section_nr(pnum_begin, pnum) {
                struct mem_section *ms;

Regards
Aisheng
> >                       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;
> > --
> > 2.25.1
> >
> >
>
> --
> Sincerely yours,
> Mike.