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

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Message-ID: <01356cc7-61c3-fb15-1c85-939b6366a636@redhat.com>
Date:   Tue, 25 May 2021 09:52:28 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Dong Aisheng <aisheng.dong@....com>, linux-mm@...ck.org
Cc:     linux-kernel@...r.kernel.org, dongas86@...il.com,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 2/5] mm/sparse: free section usage memory in case
 populate_section_memmap failed

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?

-- 
Thanks,

David / dhildenb