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, 56 insertions, 16 deletions

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 7c3628a8b486..7ef6ae964e8f 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -35,10 +35,11 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
 }
 #endif
 
-static unsigned long change_pte_range(struct mm_struct *mm, pmd_t *pmd,
+static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
                 unsigned long addr, unsigned long end, pgprot_t newprot,
-                int dirty_accountable)
+                int dirty_accountable, int prot_numa)
 {
+        struct mm_struct *mm = vma->vm_mm;
         pte_t *pte, oldpte;
         spinlock_t *ptl;
         unsigned long pages = 0;
@@ -49,19 +50,39 @@ static unsigned long change_pte_range(struct mm_struct *mm, pmd_t *pmd,
                 oldpte = *pte;
                 if (pte_present(oldpte)) {
                         pte_t ptent;
+                        bool updated = false;
 
                         ptent = ptep_modify_prot_start(mm, addr, pte);
-                        ptent = pte_modify(ptent, newprot);
+                        if (!prot_numa) {
+                                ptent = pte_modify(ptent, newprot);
+                                updated = true;
+                        } else {
+                                struct page *page;
+
+                                page = vm_normal_page(vma, addr, oldpte);
+                                if (page) {
+                                        /* only check non-shared pages */
+                                        if (!pte_numa(oldpte) &&
+                                            page_mapcount(page) == 1) {
+                                                ptent = pte_mknuma(ptent);
+                                                updated = true;
+                                        }
+                                }
+                        }
 
                         /*
                          * Avoid taking write faults for pages we know to be
                          * dirty.
                          */
-                        if (dirty_accountable && pte_dirty(ptent))
+                        if (dirty_accountable && pte_dirty(ptent)) {
                                 ptent = pte_mkwrite(ptent);
+                                updated = true;
+                        }
+
+                        if (updated)
+                                pages++;
 
                         ptep_modify_prot_commit(mm, addr, pte, ptent);
-                        pages++;
                 } else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
                         swp_entry_t entry = pte_to_swp_entry(oldpte);
 
@@ -83,9 +104,25 @@ static unsigned long change_pte_range(struct mm_struct *mm, pmd_t *pmd,
         return pages;
 }
 
+#ifdef CONFIG_NUMA_BALANCING
+static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr,
+                pmd_t *pmd)
+{
+        spin_lock(&mm->page_table_lock);
+        set_pmd_at(mm, addr & PMD_MASK, pmd, pmd_mknuma(*pmd));
+        spin_unlock(&mm->page_table_lock);
+}
+#else
+static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr,
+                pmd_t *pmd)
+{
+        BUG();
+}
+#endif /* CONFIG_NUMA_BALANCING */
+
 static inline unsigned long change_pmd_range(struct vm_area_struct *vma, pud_t *pud,
                 unsigned long addr, unsigned long end, pgprot_t newprot,
-                int dirty_accountable)
+                int dirty_accountable, int prot_numa)
 {
         pmd_t *pmd;
         unsigned long next;
@@ -97,7 +134,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, pud_t *
                 if (pmd_trans_huge(*pmd)) {
                         if (next - addr != HPAGE_PMD_SIZE)
                                 split_huge_page_pmd(vma->vm_mm, pmd);
-                        else if (change_huge_pmd(vma, pmd, addr, newprot)) {
+                        else if (change_huge_pmd(vma, pmd, addr, newprot, prot_numa)) {
                                 pages += HPAGE_PMD_NR;
                                 continue;
                         }
@@ -105,8 +142,11 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, pud_t *
                 }
                 if (pmd_none_or_clear_bad(pmd))
                         continue;
-                pages += change_pte_range(vma->vm_mm, pmd, addr, next, newprot,
-                                 dirty_accountable);
+                pages += change_pte_range(vma, pmd, addr, next, newprot,
+                                 dirty_accountable, prot_numa);
+
+                if (prot_numa)
+                        change_pmd_protnuma(vma->vm_mm, addr, pmd);
         } while (pmd++, addr = next, addr != end);
 
         return pages;
@@ -114,7 +154,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, pud_t *
 
 static inline unsigned long change_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
                 unsigned long addr, unsigned long end, pgprot_t newprot,
-                int dirty_accountable)
+                int dirty_accountable, int prot_numa)
 {
         pud_t *pud;
         unsigned long next;
@@ -126,7 +166,7 @@ static inline unsigned long change_pud_range(struct vm_area_struct *vma, pgd_t *
                 if (pud_none_or_clear_bad(pud))
                         continue;
                 pages += change_pmd_range(vma, pud, addr, next, newprot,
-                                 dirty_accountable);
+                                 dirty_accountable, prot_numa);
         } while (pud++, addr = next, addr != end);
 
         return pages;
@@ -134,7 +174,7 @@ static inline unsigned long change_pud_range(struct vm_area_struct *vma, pgd_t *
 
 static unsigned long change_protection_range(struct vm_area_struct *vma,
                 unsigned long addr, unsigned long end, pgprot_t newprot,
-                int dirty_accountable)
+                int dirty_accountable, int prot_numa)
 {
         struct mm_struct *mm = vma->vm_mm;
         pgd_t *pgd;
@@ -150,7 +190,7 @@ static unsigned long change_protection_range(struct vm_area_struct *vma,
                 if (pgd_none_or_clear_bad(pgd))
                         continue;
                 pages += change_pud_range(vma, pgd, addr, next, newprot,
-                                 dirty_accountable);
+                                 dirty_accountable, prot_numa);
         } while (pgd++, addr = next, addr != end);
 
         /* Only flush the TLB if we actually modified any entries: */
@@ -162,7 +202,7 @@ static unsigned long change_protection_range(struct vm_area_struct *vma,
 
 unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
                        unsigned long end, pgprot_t newprot,
-                       int dirty_accountable)
+                       int dirty_accountable, int prot_numa)
 {
         struct mm_struct *mm = vma->vm_mm;
         unsigned long pages;
@@ -171,7 +211,7 @@ unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
         if (is_vm_hugetlb_page(vma))
                 pages = hugetlb_change_protection(vma, start, end, newprot);
         else
-                pages = change_protection_range(vma, start, end, newprot, dirty_accountable);
+                pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
         mmu_notifier_invalidate_range_end(mm, start, end);
 
         return pages;
@@ -249,7 +289,7 @@ success:
                 dirty_accountable = 1;
         }
 
-        change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable);
+        change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable, 0);
 
         vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
         vm_stat_account(mm, newflags, vma->vm_file, nrpages);