Re: [PATCH 2/3] mm/page_ext: remove rollback for untouched mem_section in online_page_ext

[Andrew Morton]

On Fri, 14 Jul 2023 19:47:48 +0800 Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx> wrote:

> If init_section_page_ext failed, we only need rollback for mem_section
> before failed mem_section. Make rollback end point to failed mem_section
> to remove unnecessary rollback.
> 
> As pfn += PAGES_PER_SECTION will be executed even if init_section_page_ext
> failed. So pfn points to mem_section after failed mem_section. Subtract
> one mem_section from pfn to get failed mem_section.
> 
> ...
>
> --- a/mm/page_ext.c
> +++ b/mm/page_ext.c
> @@ -424,6 +424,7 @@ static int __meminit online_page_ext(unsigned long start_pfn,
>  		return 0;
>  
>  	/* rollback */
> +	end = pfn - PAGES_PER_SECTION;
>  	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
>  		__free_page_ext(pfn);
>  

This is a bugfix, yes?

I guess init_section_page_ext() never fails for anyone...