[RFC PATCH 3/9] mm: Move change_prot_numa outside CONFIG_ARCH_USES_NUMA_PROT_NONE

[Aneesh Kumar K.V]

From: "Aneesh Kumar K.V" <aneesh.kumar at linux.vnet.ibm.com>

change_prot_numa should work even if _PAGE_NUMA != _PAGE_PROTNONE.
On archs like ppc64 that don't use _PAGE_PROTNONE and also have
a separate page table outside linux pagetable, we just need to
make sure that when calling change_prot_numa we flush the
hardware page table entry so that next page access  result in a numa
fault.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.vnet.ibm.com>
---
 include/linux/mm.h | 3 ---
 mm/mempolicy.c     | 9 ---------
 2 files changed, 12 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 8b6e55e..5ab0e22 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1668,11 +1668,8 @@ static inline pgprot_t vm_get_page_prot(unsigned long vm_flags)
 }
 #endif
 
-#ifdef CONFIG_ARCH_USES_NUMA_PROT_NONE
 unsigned long change_prot_numa(struct vm_area_struct *vma,
 			unsigned long start, unsigned long end);
-#endif
-
 struct vm_area_struct *find_extend_vma(struct mm_struct *, unsigned long addr);
 int remap_pfn_range(struct vm_area_struct *, unsigned long addr,
 			unsigned long pfn, unsigned long size, pgprot_t);
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 0472964..efb4300 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -612,7 +612,6 @@ static inline int queue_pages_pgd_range(struct vm_area_struct *vma,
 	return 0;
 }
 
-#ifdef CONFIG_ARCH_USES_NUMA_PROT_NONE
 /*
  * This is used to mark a range of virtual addresses to be inaccessible.
  * These are later cleared by a NUMA hinting fault. Depending on these
@@ -626,7 +625,6 @@ unsigned long change_prot_numa(struct vm_area_struct *vma,
 			unsigned long addr, unsigned long end)
 {
 	int nr_updated;
-	BUILD_BUG_ON(_PAGE_NUMA != _PAGE_PROTNONE);
 
 	nr_updated = change_protection(vma, addr, end, vma->vm_page_prot, 0, 1);
 	if (nr_updated)
@@ -634,13 +632,6 @@ unsigned long change_prot_numa(struct vm_area_struct *vma,
 
 	return nr_updated;
 }
-#else
-static unsigned long change_prot_numa(struct vm_area_struct *vma,
-			unsigned long addr, unsigned long end)
-{
-	return 0;
-}
-#endif /* CONFIG_ARCH_USES_NUMA_PROT_NONE */
 
 /*
  * Walk through page tables and collect pages to be migrated.
-- 
1.8.3.2