linux-kernel - Re: [PATCH] mm/sparse.c: mark populate_section_memmap as _

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Date:   Wed, 30 Oct 2019 09:14:04 +0100
From:   Oscar Salvador <osalvador@...e.de>
To:     Ilya Leoshkevich <iii@...ux.ibm.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>
Subject: Re: [PATCH] mm/sparse.c: mark populate_section_memmap as __meminit

On Mon, Oct 28, 2019 at 05:55:49PM +0100, Ilya Leoshkevich wrote:
> Building the kernel on s390 with -Og produces the following warning:
> 
> WARNING: vmlinux.o(.text+0x28dabe): Section mismatch in reference from the function populate_section_memmap() to the function .meminit.text:__populate_section_memmap()
> The function populate_section_memmap() references
> the function __meminit __populate_section_memmap().
> This is often because populate_section_memmap lacks a __meminit
> annotation or the annotation of __populate_section_memmap is wrong.
> 
> While -Og is not supported, in theory this might still happen with
> another compiler or on another architecture. So fix this by using the
> correct section annotations.
> 
> Signed-off-by: Ilya Leoshkevich <iii@...ux.ibm.com>
> ---
>  mm/sparse.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/sparse.c b/mm/sparse.c
> index f6891c1992b1..0f1f36443a96 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -448,7 +448,7 @@ static unsigned long __init section_map_size(void)
>  	return PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
>  }
>  
> -struct page __init *__populate_section_memmap(unsigned long pfn,
> +struct page __meminit *__populate_section_memmap(unsigned long pfn,
>  		unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
>  {
>  	unsigned long size = section_map_size();
> @@ -647,7 +647,7 @@ void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
>  #endif
>  
>  #ifdef CONFIG_SPARSEMEM_VMEMMAP
> -static struct page *populate_section_memmap(unsigned long pfn,
> +static struct page * __meminit populate_section_memmap(unsigned long pfn,
>  		unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
>  {
>  	return __populate_section_memmap(pfn, nr_pages, nid, altmap);
> @@ -669,7 +669,7 @@ static void free_map_bootmem(struct page *memmap)
>  	vmemmap_free(start, end, NULL);
>  }
>  #else
> -struct page *populate_section_memmap(unsigned long pfn,
> +struct page * __meminit populate_section_memmap(unsigned long pfn,
>  		unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
>  {
>  	struct page *page, *ret;

I did not really check deep, but I __think__ you only need to add __meminit in
populate_section_memmap functions.

__populate_section_memmap for SPARSE case is only used at init phase.


-- 
Oscar Salvador
SUSE L3