Re: linux-next: build failure after merge of the final tree (hwpoison tree related)

[Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>]

Hi,

On Mon, Sep 27, 2010 at 03:55:51PM +1000, Stephen Rothwell wrote:
> Hi Andi,
> 
> After merging the final tree, today's linux-next build (powerpc allnoconfig)
> failed like this:
> 
> mm/mprotect.o: In function `migrate_huge_page_move_mapping':
> mprotect.c:(.text+0x0): multiple definition of `migrate_huge_page_move_mapping'
> mm/shmem.o:shmem.c:(.text+0x0): first defined here
> mm/rmap.o: In function `migrate_huge_page_move_mapping':
> rmap.c:(.text+0x0): multiple definition of `migrate_huge_page_move_mapping'
> mm/shmem.o:shmem.c:(.text+0x0): first defined here
> 
> Caused by commit 7b217c52ce7f33379beb27aa7685109fa74ed6bf ("hugetlb:
> hugepage migration core").
> 
> This function is declared as "extern int ..." with a body in
> include/linux/migrate.h for the non CONFIG_MIGRATION case.

This build error reappears for x86_64 with !CONFIG_MIGRATION.
As you commented, "extern int" declaration causes it.
So please apply the following patch.

Thank you for reporting.

Thanks,
Naoya Horiguchi

---
Date: Thu, 30 Sep 2010 09:56:02 +0900
Subject: [PATCH] fix build error with !CONFIG_MIGRATION

migrate_huge_page_move_mapping() is declared as "extern int ..."
in include/linux/migrate.h for !CONFIG_MIGRATION,
which causes the build error like below:

  mm/mprotect.o: In function `migrate_huge_page_move_mapping':
  mprotect.c:(.text+0x0): multiple definition of `migrate_huge_page_move_mapping'
  mm/shmem.o:shmem.c:(.text+0x0): first defined here
  mm/rmap.o: In function `migrate_huge_page_move_mapping':
  rmap.c:(.text+0x0): multiple definition of `migrate_huge_page_move_mapping'
  mm/shmem.o:shmem.c:(.text+0x0): first defined here

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
 include/linux/migrate.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 3c1941e..085527f 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -50,7 +50,7 @@ static inline int migrate_vmas(struct mm_struct *mm,
 static inline void migrate_page_copy(struct page *newpage,
 				     struct page *page) {}
 
-extern int migrate_huge_page_move_mapping(struct address_space *mapping,
+static inline int migrate_huge_page_move_mapping(struct address_space *mapping,
 				  struct page *newpage, struct page *page)
 {
 	return -ENOSYS;
-- 
1.7.2.3