On 11/01/2018 11:06, Michal Hocko wrote:
On Thu 11-01-18 09:53:31, Alexandre Ghiti wrote:
The only definition of vmf_insert_pfn_pud depends on
CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD being defined. Then its declaration in
include/linux/huge_mm.h should have the same restriction so that we do
not expose this function if CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD is
not defined.
Why is this a problem? Compiler should simply throw away any
declarations which are not used?
It is not a big problem but surrounding the declaration with the #ifdef
makes the compilation of external modules fail with an "error: implicit
declaration of function vmf_insert_pfn_pud" if
CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD is not defined. I think it is
cleaner than generating a .ko which would not load anyway.
Signed-off-by: Alexandre Ghiti <aghiti@xxxxxxxxx>
---
include/linux/huge_mm.h | 2 ++
1 file changed, 2 insertions(+)
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index a8a1262..11794f6a 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -48,8 +48,10 @@ extern int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
int prot_numa);
int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
pmd_t *pmd, pfn_t pfn, bool write);
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
int vmf_insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
pud_t *pud, pfn_t pfn, bool write);
+#endif
enum transparent_hugepage_flag {
TRANSPARENT_HUGEPAGE_FLAG,
TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
--
2.1.4
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