mm: convert p[te|md]_mknonnuma and remaining page table manipulations

With PROT_NONE, the traditional page table manipulation functions are
sufficient.

[andre.przywara@arm.com: fix compiler warning in pmdp_invalidate()]
[akpm@linux-foundation.org: fix build with STRICT_MM_TYPECHECKS]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

8 files changed, 21 insertions, 38 deletions

diff --git a/arch/arm/include/asm/pgtable-3level.h b/arch/arm/include/asm/pgtable-3level.h
index 18dbc82f85e5..423a5ac09d3a 100644
--- a/arch/arm/include/asm/pgtable-3level.h
+++ b/arch/arm/include/asm/pgtable-3level.h
@@ -257,7 +257,10 @@ PMD_BIT_FUNC(mkyoung,   |= PMD_SECT_AF);
 #define mk_pmd(page,prot)       pfn_pmd(page_to_pfn(page),prot)
 
 /* represent a notpresent pmd by zero, this is used by pmdp_invalidate */
-#define pmd_mknotpresent(pmd)   (__pmd(0))
+static inline pmd_t pmd_mknotpresent(pmd_t pmd)
+{
+        return __pmd(0);
+}
 
 static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
 {
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index f10b20f05159..062bd252e994 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -31,8 +31,7 @@ extern int move_huge_pmd(struct vm_area_struct *vma,
                          unsigned long new_addr, unsigned long old_end,
                          pmd_t *old_pmd, pmd_t *new_pmd);
 extern int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
-                        unsigned long addr, pgprot_t newprot,
-                        int prot_numa);
+                        unsigned long addr, pgprot_t newprot);
 
 enum transparent_hugepage_flag {
         TRANSPARENT_HUGEPAGE_FLAG,
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 915941c45169..cb9b3e847dac 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1355,9 +1355,8 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
         goto out;
 clear_pmdnuma:
         BUG_ON(!PageLocked(page));
-        pmd = pmd_mknonnuma(pmd);
+        pmd = pmd_modify(pmd, vma->vm_page_prot);
         set_pmd_at(mm, haddr, pmdp, pmd);
-        VM_BUG_ON(pmd_protnone(*pmdp));
         update_mmu_cache_pmd(vma, addr, pmdp);
         unlock_page(page);
 out_unlock:
@@ -1472,7 +1471,7 @@ out:
  *  - HPAGE_PMD_NR is protections changed and TLB flush necessary
  */
 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
-                unsigned long addr, pgprot_t newprot, int prot_numa)
+                unsigned long addr, pgprot_t newprot)
 {
         struct mm_struct *mm = vma->vm_mm;
         spinlock_t *ptl;
@@ -1481,29 +1480,11 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
         if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
                 pmd_t entry;
                 ret = 1;
-                if (!prot_numa) {
-                        entry = pmdp_get_and_clear_notify(mm, addr, pmd);
-                        if (pmd_protnone(entry))
-                                entry = pmd_mknonnuma(entry);
-                        entry = pmd_modify(entry, newprot);
-                        ret = HPAGE_PMD_NR;
-                        set_pmd_at(mm, addr, pmd, entry);
-                        BUG_ON(pmd_write(entry));
-                } else {
-                        struct page *page = pmd_page(*pmd);
-
-                        /*
-                         * Do not trap faults against the zero page. The
-                         * read-only data is likely to be read-cached on the
-                         * local CPU cache and it is less useful to know about
-                         * local vs remote hits on the zero page.
-                         */
-                        if (!is_huge_zero_page(page) &&
-                            !pmd_protnone(*pmd)) {
-                                pmdp_set_numa(mm, addr, pmd);
-                                ret = HPAGE_PMD_NR;
-                        }
-                }
+                entry = pmdp_get_and_clear_notify(mm, addr, pmd);
+                entry = pmd_modify(entry, newprot);
+                ret = HPAGE_PMD_NR;
+                set_pmd_at(mm, addr, pmd, entry);
+                BUG_ON(pmd_write(entry));
                 spin_unlock(ptl);
         }
 
diff --git a/mm/memory.c b/mm/memory.c
index 92e6a6299e86..d7921760cf79 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3018,9 +3018,9 @@ static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
         * validation through pte_unmap_same(). It's of NUMA type but
         * the pfn may be screwed if the read is non atomic.
         *
-        * ptep_modify_prot_start is not called as this is clearing
-        * the _PAGE_NUMA bit and it is not really expected that there
-        * would be concurrent hardware modifications to the PTE.
+        * We can safely just do a "set_pte_at()", because the old
+        * page table entry is not accessible, so there would be no
+        * concurrent hardware modifications to the PTE.
         */
         ptl = pte_lockptr(mm, pmd);
         spin_lock(ptl);
@@ -3029,7 +3029,9 @@ static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
                 goto out;
         }
 
-        pte = pte_mknonnuma(pte);
+        /* Make it present again */
+        pte = pte_modify(pte, vma->vm_page_prot);
+        pte = pte_mkyoung(pte);
         set_pte_at(mm, addr, ptep, pte);
         update_mmu_cache(vma, addr, ptep);
 
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index f1bd23803576..c75f4dcec808 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -569,7 +569,7 @@ unsigned long change_prot_numa(struct vm_area_struct *vma,
 {
         int nr_updated;
 
-        nr_updated = change_protection(vma, addr, end, vma->vm_page_prot, 0, 1);
+        nr_updated = change_protection(vma, addr, end, PAGE_NONE, 0, 1);
         if (nr_updated)
                 count_vm_numa_events(NUMA_PTE_UPDATES, nr_updated);
 
diff --git a/mm/migrate.c b/mm/migrate.c
index 5e8f03a8de2a..85e042686031 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1847,7 +1847,7 @@ out_fail:
 out_dropref:
         ptl = pmd_lock(mm, pmd);
         if (pmd_same(*pmd, entry)) {
-                entry = pmd_mknonnuma(entry);
+                entry = pmd_modify(entry, vma->vm_page_prot);
                 set_pmd_at(mm, mmun_start, pmd, entry);
                 update_mmu_cache_pmd(vma, address, &entry);
         }
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 44ffa698484d..76824d73380d 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -142,7 +142,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
                                 split_huge_page_pmd(vma, addr, pmd);
                         else {
                                 int nr_ptes = change_huge_pmd(vma, pmd, addr,
-                                                newprot, prot_numa);
+                                                newprot);
 
                                 if (nr_ptes) {
                                         if (nr_ptes == HPAGE_PMD_NR) {
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index 4b8ad760dde3..c25f94b33811 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -193,8 +193,6 @@ void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
                      pmd_t *pmdp)
 {
         pmd_t entry = *pmdp;
-        if (pmd_protnone(entry))
-                entry = pmd_mknonnuma(entry);
         set_pmd_at(vma->vm_mm, address, pmdp, pmd_mknotpresent(entry));
         flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
 }