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From: Mel Gorman <mgorman@techsingularity.net>
To: Matteo Croce <mcroce@linux.microsoft.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@kernel.org>,
	David Hildenbrand <david@redhat.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Dan Streetman <ddstreet@ieee.org>, Yang Shi <shy828301@gmail.com>,
	Linux-MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 03/14] mm/page_alloc: Make should_fail_alloc_page a static function should_fail_alloc_page static
Date: Fri, 9 Jul 2021 10:30:40 +0100	[thread overview]
Message-ID: <20210709093040.GX3840@techsingularity.net> (raw)
In-Reply-To: <20210708211648.13659bb5@linux.microsoft.com>

On Thu, Jul 08, 2021 at 09:18:44PM +0200, Matteo Croce wrote:
> On Thu, 20 May 2021 09:47:58 +0100
> Mel Gorman <mgorman@techsingularity.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@techsingularity.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.
> 

The alternative fix of making the symbol global was rejected. eBPF needs
to figure out a way of instrumenting code that is is unused by the kernel
and not globally visible but I don't know how that might be achieved.

-- 
Mel Gorman
SUSE Labs


  reply	other threads:[~2021-07-09  9:30 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-20  8:47 [PATCH 00/14] Clean W=1 build warnings for mm/ Mel Gorman
2021-05-20  8:47 ` [PATCH 01/14] mm/vmscan: Remove kerneldoc-like comment from isolate_lru_pages Mel Gorman
2021-05-20  8:47 ` [PATCH 02/14] mm/vmalloc: Include header for prototype of set_iounmap_nonlazy Mel Gorman
2021-05-20  8:47 ` [PATCH 03/14] mm/page_alloc: Make should_fail_alloc_page a static function should_fail_alloc_page static Mel Gorman
2021-07-08 19:18   ` Matteo Croce
2021-07-09  9:30     ` Mel Gorman [this message]
2021-05-20  8:47 ` [PATCH 04/14] mm/mapping_dirty_helpers: Remove double Note in kerneldoc Mel Gorman
2021-05-20  8:48 ` [PATCH 05/14] mm/early_ioremap: Add prototype for early_memremap_pgprot_adjust Mel Gorman
2021-05-20  8:48 ` [PATCH 06/14] mm/memcontrol.c: Fix kerneldoc comment for mem_cgroup_calculate_protection Mel Gorman
2021-05-20 23:24   ` Chris Down
2021-05-20  8:48 ` [PATCH 07/14] mm/memory_hotplug: Fix kerneldoc comment for __try_online_node Mel Gorman
2021-05-20 10:42   ` David Hildenbrand
2021-05-20  8:48 ` [PATCH 08/14] mm/memory_hotplug: Fix kerneldoc comment for __remove_memory Mel Gorman
2021-05-20 10:42   ` David Hildenbrand
2021-05-20  8:48 ` [PATCH 09/14] mm/zbud: Add kerneldoc fields for zbud_pool Mel Gorman
2021-05-20  8:48 ` [PATCH 10/14] mm/z3fold: Add kerneldoc fields for z3fold_pool Mel Gorman
2021-05-20  8:48 ` [PATCH 11/14] mm/swap: Make swap_address_space an inline function Mel Gorman
2021-05-20  8:48 ` [PATCH 12/14] mm/mmap_lock: Remove dead code for !CONFIG_TRACING configurations Mel Gorman
2021-05-20  8:48 ` [PATCH 13/14] mm/page_alloc: Move prototype for find_suitable_fallback Mel Gorman
2021-05-20  8:48 ` [PATCH 14/14] mm/swap: Make NODE_DATA an inline function on CONFIG_FLATMEM Mel Gorman
2021-05-20 22:51 ` [PATCH 00/14] Clean W=1 build warnings for mm/ Yang Shi
2021-05-25 11:48 ` Vlastimil Babka
2021-05-25 14:25   ` Mel Gorman

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