mm: mempolicy: Implement change_prot_numa() in terms of change_protection()

This patch converts change_prot_numa() to use change_protection(). As
pte_numa and friends check the PTE bits directly it is necessary for
change_protection() to use pmd_mknuma(). Hence the required
modifications to change_protection() are a little clumsy but the
end result is that most of the numa page table helpers are just one or
two instructions.

Signed-off-by: Mel Gorman <mgorman@suse.de>

1 files changed, 12 insertions, 2 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 5723b551c023..d79f7a55bf6f 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1147,7 +1147,7 @@ out:
 }
 
 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
-                unsigned long addr, pgprot_t newprot)
+                unsigned long addr, pgprot_t newprot, int prot_numa)
 {
         struct mm_struct *mm = vma->vm_mm;
         int ret = 0;
@@ -1155,7 +1155,17 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
         if (__pmd_trans_huge_lock(pmd, vma) == 1) {
                 pmd_t entry;
                 entry = pmdp_get_and_clear(mm, addr, pmd);
-                entry = pmd_modify(entry, newprot);
+                if (!prot_numa)
+                        entry = pmd_modify(entry, newprot);
+                else {
+                        struct page *page = pmd_page(*pmd);
+
+                        /* only check non-shared pages */
+                        if (page_mapcount(page) == 1 &&
+                            !pmd_numa(*pmd)) {
+                                entry = pmd_mknuma(entry);
+                        }
+                }
                 set_pmd_at(mm, addr, pmd, entry);
                 spin_unlock(&vma->vm_mm->page_table_lock);
                 ret = 1;