linux-kernel - Re: [PATCH 2/3] mm/sparse: Optimize sparse_add_one

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Date:   Wed, 20 Mar 2019 09:56:50 +0200
From:   Mike Rapoport <rppt@...ux.ibm.com>
To:     Baoquan He <bhe@...hat.com>
Cc:     linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
        pasha.tatashin@...cle.com, mhocko@...e.com,
        rppt@...ux.vnet.ibm.com, richard.weiyang@...il.com,
        linux-mm@...ck.org
Subject: Re: [PATCH 2/3] mm/sparse: Optimize sparse_add_one_section()

On Wed, Mar 20, 2019 at 03:35:39PM +0800, Baoquan He wrote:
> Reorder the allocation of usemap and memmap since usemap allocation
> is much smaller and simpler. Otherwise hard work is done to make
> memmap ready, then have to rollback just because of usemap allocation
> failure.
> 
> Signed-off-by: Baoquan He <bhe@...hat.com>
> ---
>  mm/sparse.c | 13 +++++++------
>  1 file changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/mm/sparse.c b/mm/sparse.c
> index 0a0f82c5d969..054b99f74181 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -697,16 +697,17 @@ int __meminit sparse_add_one_section(int nid, unsigned long start_pfn,
>  	ret = sparse_index_init(section_nr, nid);
>  	if (ret < 0 && ret != -EEXIST)
>  		return ret;
> -	ret = 0;
> -	memmap = kmalloc_section_memmap(section_nr, nid, altmap);
> -	if (!memmap)
> -		return -ENOMEM;
> +
>  	usemap = __kmalloc_section_usemap();
> -	if (!usemap) {
> -		__kfree_section_memmap(memmap, altmap);
> +	if (!usemap)
> +		return -ENOMEM;
> +	memmap = kmalloc_section_memmap(section_nr, nid, altmap);
> +	if (!memmap) {
> +		kfree(usemap);

If you are anyway changing this why not to switch to goto's for error
handling?

>  		return -ENOMEM;
>  	}
> 
> +	ret = 0;
>  	ms = __pfn_to_section(start_pfn);
>  	if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
>  		ret = -EEXIST;
> -- 
> 2.17.2
> 

-- 
Sincerely yours,
Mike.