On Mon, Jul 06, 2015 at 03:05:09PM -0700, Andrew Morton wrote:
> On Sat, 4 Jul 2015 21:10:08 +0300 "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> wrote:
>
> > On Sat, Jul 04, 2015 at 05:26:47PM +0800, kbuild test robot wrote:
> > > tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > > head: 14a6f1989dae9445d4532941bdd6bbad84f4c8da
> > > commit: 3b242c66ccbd60cf47ab0e8992119d9617548c23 x86: mm: enable deferred struct page initialisation on x86-64
> > > date: 3 days ago
> > > config: x86_64-randconfig-x006-201527 (attached as .config)
> > > reproduce:
> > > git checkout 3b242c66ccbd60cf47ab0e8992119d9617548c23
> > > # save the attached .config to linux build tree
> > > make ARCH=x86_64
> > >
> > > All warnings (new ones prefixed by >>):
> > >
> > > mm/page_alloc.c: In function 'early_page_uninitialised':
> > > >> mm/page_alloc.c:247:6: warning: unused variable 'nid' [-Wunused-variable]
> > > int nid = early_pfn_to_nid(pfn);
> >
> > We can silence the warning with something like patch below. But I'm not
> > sure it worth it.
> >
> > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> > index 754c25966a0a..746a6a7b0535 100644
> > --- a/include/linux/mmzone.h
> > +++ b/include/linux/mmzone.h
> > @@ -911,7 +911,7 @@ extern char numa_zonelist_order[];
> > #ifndef CONFIG_NEED_MULTIPLE_NODES
> >
> > extern struct pglist_data contig_page_data;
> > -#define NODE_DATA(nid) (&contig_page_data)
> > +#define NODE_DATA(nid) ((void)nid, &contig_page_data)
> > #define NODE_MEM_MAP(nid) mem_map
> >
> > #else /* CONFIG_NEED_MULTIPLE_NODES */
>
> Sigh. Macros do suck. If NODE_DATA was a regular old C function this
> warning wouldn't occur. Problem is, we should then rename it to
> "node_data" and that would require 246 edits.
>
> I suppose we could compromise and do
>
> static inline struct pglist_data *NODE_DATA(int nid)
>
> ?
It might set a bad precedent. While I know there are counter examples,
I generally expect CAPITAL_NAMES to be macros of some description --
usually constants. This is a relatively harmless warning thats easy to
work around so how about this?
---8<---
mm, meminit: Suppress unused memory variable warning
The kbuild test robot reported the following
tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 14a6f1989dae9445d4532941bdd6bbad84f4c8da
commit: 3b242c66ccbd60cf47ab0e8992119d9617548c23 x86: mm: enable deferred struct page initialisation on x86-64
date: 3 days ago
config: x86_64-randconfig-x006-201527 (attached as .config)
reproduce:
git checkout 3b242c66ccbd60cf47ab0e8992119d9617548c23
# save the attached .config to linux build tree
make ARCH=x86_64
All warnings (new ones prefixed by >>):
mm/page_alloc.c: In function 'early_page_uninitialised':
>> mm/page_alloc.c:247:6: warning: unused variable 'nid' [-Wunused-variable]
int nid = early_pfn_to_nid(pfn);
It's due to the NODE_DATA macro ignoring the nid parameter on !NUMA
configurations. This patch avoids the warning by not declaring nid.
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
---
mm/page_alloc.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 506eac8b38af..ac05e7ae399e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -246,9 +246,7 @@ static inline void reset_deferred_meminit(pg_data_t *pgdat)
/* Returns true if the struct page for the pfn is uninitialised */
static inline bool __meminit early_page_uninitialised(unsigned long pfn)
{
- int nid = early_pfn_to_nid(pfn);
-
- if (pfn >= NODE_DATA(nid)->first_deferred_pfn)
+ if (pfn >= NODE_DATA(early_pfn_to_nid(pfn))->first_deferred_pfn)
return true;
return false;
--
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