linux-kernel - Re: [PATCH 9/9] mm/z3fold: remove unneeded return value of z3fold_compact

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Date:   Wed, 2 Mar 2022 16:56:26 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     Vitaly Wool <vitaly.wool@...sulko.com>
CC:     Andrew Morton <akpm@...ux-foundation.org>,
        Linux-MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 9/9] mm/z3fold: remove unneeded return value of
 z3fold_compact_page()

On 2022/3/2 16:40, Vitaly Wool wrote:
> On Sat, Feb 19, 2022 at 10:26 AM Miaohe Lin <linmiaohe@...wei.com> wrote:
>>
>> Remove the unneeded return value of z3fold_compact_page() as it's
>> never checked.
> 
> It was a sort of hook for gathering extended compaction statistics in
> future. Do you really gain a lot by removing this?

I see. So I shouldn't discard the return value though it looks unused.
This is just for cleanup purpose so let's just drop this patch.

Many thanks for your time and Reviewed-by tag in this series! :)

> 
> ~Vitaly
> 
>> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
>> ---
>>  mm/z3fold.c | 14 +++++---------
>>  1 file changed, 5 insertions(+), 9 deletions(-)
>>
>> diff --git a/mm/z3fold.c b/mm/z3fold.c
>> index 83b5a3514427..db41b4227ec7 100644
>> --- a/mm/z3fold.c
>> +++ b/mm/z3fold.c
>> @@ -746,18 +746,18 @@ static struct z3fold_header *compact_single_buddy(struct z3fold_header *zhdr)
>>
>>  #define BIG_CHUNK_GAP  3
>>  /* Has to be called with lock held */
>> -static int z3fold_compact_page(struct z3fold_header *zhdr)
>> +static void z3fold_compact_page(struct z3fold_header *zhdr)
>>  {
>>         struct page *page = virt_to_page(zhdr);
>>
>>         if (test_bit(MIDDLE_CHUNK_MAPPED, &page->private))
>> -               return 0; /* can't move middle chunk, it's used */
>> +               return; /* can't move middle chunk, it's used */
>>
>>         if (unlikely(PageIsolated(page)))
>> -               return 0;
>> +               return;
>>
>>         if (zhdr->middle_chunks == 0)
>> -               return 0; /* nothing to compact */
>> +               return; /* nothing to compact */
>>
>>         if (zhdr->first_chunks == 0 && zhdr->last_chunks == 0) {
>>                 /* move to the beginning */
>> @@ -766,7 +766,7 @@ static int z3fold_compact_page(struct z3fold_header *zhdr)
>>                 zhdr->middle_chunks = 0;
>>                 zhdr->start_middle = 0;
>>                 zhdr->first_num++;
>> -               return 1;
>> +               return;
>>         }
>>
>>         /*
>> @@ -778,7 +778,6 @@ static int z3fold_compact_page(struct z3fold_header *zhdr)
>>                         BIG_CHUNK_GAP) {
>>                 mchunk_memmove(zhdr, zhdr->first_chunks + ZHDR_CHUNKS);
>>                 zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
>> -               return 1;
>>         } else if (zhdr->last_chunks != 0 && zhdr->first_chunks == 0 &&
>>                    TOTAL_CHUNKS - (zhdr->last_chunks + zhdr->start_middle
>>                                         + zhdr->middle_chunks) >=
>> @@ -787,10 +786,7 @@ static int z3fold_compact_page(struct z3fold_header *zhdr)
>>                         zhdr->middle_chunks;
>>                 mchunk_memmove(zhdr, new_start);
>>                 zhdr->start_middle = new_start;
>> -               return 1;
>>         }
>> -
>> -       return 0;
>>  }
>>
>>  static void do_compact_page(struct z3fold_header *zhdr, bool locked)
>> --
>> 2.23.0
>>
> .
>