linux-kernel - Re: [PATCH 03/14] mm/page_alloc: Make should_fail_alloc_page a static function should_fail_alloc

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Date:   Thu, 8 Jul 2021 21:18:44 +0200
From:   Matteo Croce <mcroce@...ux.microsoft.com>
To:     Mel Gorman <mgorman@...hsingularity.net>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...nel.org>,
        David Hildenbrand <david@...hat.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Dan Streetman <ddstreet@...e.org>,
        Yang Shi <shy828301@...il.com>, Linux-MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 03/14] mm/page_alloc: Make should_fail_alloc_page a
 static function should_fail_alloc_page static

On Thu, 20 May 2021 09:47:58 +0100
Mel Gorman <mgorman@...hsingularity.net> wrote:

> make W=1 generates the following warning for mm/page_alloc.c
> 
>   mm/page_alloc.c:3651:15: warning: no previous prototype for
> ‘should_fail_alloc_page’ [-Wmissing-prototypes] noinline bool
> should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
> ^~~~~~~~~~~~~~~~~~~~~~
> 
> This function is deliberately split out for BPF to allow errors to be
> injected. The function is not used anywhere else so it is local to
> the file. Make it static which should still allow error injection
> to be used similar to how block/blk-core.c:should_fail_bio() works.
> 
> Signed-off-by: Mel Gorman <mgorman@...hsingularity.net>
> ---
>  mm/page_alloc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index aaa1655cf682..26cc1a4e639b 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3648,7 +3648,7 @@ static inline bool
> __should_fail_alloc_page(gfp_t gfp_mask, unsigned int order) 
>  #endif /* CONFIG_FAIL_PAGE_ALLOC */
>  
> -noinline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int
> order) +static noinline bool should_fail_alloc_page(gfp_t gfp_mask,
> unsigned int order) {
>  	return __should_fail_alloc_page(gfp_mask, order);
>  }


Hi Mel,

It seems that this breaks builds with CONFIG_DEBUG_INFO_BTF=y.
Maybe that warning was a false positive because
should_fail_alloc_page() is referenced via a macro?

I proposed to revert it, feel free to propose another fix.

Regards,
-- 
per aspera ad upstream