mm: get_user_pages: migrate out CMA pages when FOLL_DURABLE flag is set
[linux-3.10.git] / mm / pagewalk.c
index 8b1a2ce..2beeabf 100644 (file)
@@ -33,18 +33,35 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 
        pmd = pmd_offset(pud, addr);
        do {
+again:
                next = pmd_addr_end(addr, end);
-               if (pmd_none_or_clear_bad(pmd)) {
+               if (pmd_none(*pmd)) {
                        if (walk->pte_hole)
                                err = walk->pte_hole(addr, next, walk);
                        if (err)
                                break;
                        continue;
                }
+               /*
+                * This implies that each ->pmd_entry() handler
+                * needs to know about pmd_trans_huge() pmds
+                */
                if (walk->pmd_entry)
                        err = walk->pmd_entry(pmd, addr, next, walk);
-               if (!err && walk->pte_entry)
-                       err = walk_pte_range(pmd, addr, next, walk);
+               if (err)
+                       break;
+
+               /*
+                * Check this here so we only break down trans_huge
+                * pages when we _need_ to
+                */
+               if (!walk->pte_entry)
+                       continue;
+
+               split_huge_page_pmd_mm(walk->mm, addr, pmd);
+               if (pmd_none_or_trans_huge_or_clear_bad(pmd))
+                       goto again;
+               err = walk_pte_range(pmd, addr, next, walk);
                if (err)
                        break;
        } while (pmd++, addr = next, addr != end);
@@ -109,11 +126,21 @@ static int walk_hugetlb_range(struct vm_area_struct *vma,
 
        return 0;
 }
-#endif
+
+#else /* CONFIG_HUGETLB_PAGE */
+static int walk_hugetlb_range(struct vm_area_struct *vma,
+                             unsigned long addr, unsigned long end,
+                             struct mm_walk *walk)
+{
+       return 0;
+}
+
+#endif /* CONFIG_HUGETLB_PAGE */
+
+
 
 /**
  * walk_page_range - walk a memory map's page tables with a callback
- * @mm: memory map to walk
  * @addr: starting address
  * @end: ending address
  * @walk: set of callbacks to invoke for each level of the tree
@@ -127,11 +154,15 @@ static int walk_hugetlb_range(struct vm_area_struct *vma,
  * associated range, and a copy of the original mm_walk for access to
  * the ->private or ->mm fields.
  *
- * No locks are taken, but the bottom level iterator will map PTE
+ * Usually no locks are taken, but splitting transparent huge page may
+ * take page table lock. And the bottom level iterator will map PTE
  * directories from highmem if necessary.
  *
  * If any callback returns a non-zero value, the walk is aborted and
  * the return value is propagated back to the caller. Otherwise 0 is returned.
+ *
+ * walk->mm->mmap_sem must be held for at least read if walk->hugetlb_entry
+ * is !NULL.
  */
 int walk_page_range(unsigned long addr, unsigned long end,
                    struct mm_walk *walk)
@@ -139,7 +170,6 @@ int walk_page_range(unsigned long addr, unsigned long end,
        pgd_t *pgd;
        unsigned long next;
        int err = 0;
-       struct vm_area_struct *vma;
 
        if (addr >= end)
                return err;
@@ -147,31 +177,55 @@ int walk_page_range(unsigned long addr, unsigned long end,
        if (!walk->mm)
                return -EINVAL;
 
+       VM_BUG_ON(!rwsem_is_locked(&walk->mm->mmap_sem));
+
        pgd = pgd_offset(walk->mm, addr);
        do {
+               struct vm_area_struct *vma = NULL;
+
                next = pgd_addr_end(addr, end);
 
                /*
-                * handle hugetlb vma individually because pagetable walk for
-                * the hugetlb page is dependent on the architecture and
-                * we can't handled it in the same manner as non-huge pages.
+                * This function was not intended to be vma based.
+                * But there are vma special cases to be handled:
+                * - hugetlb vma's
+                * - VM_PFNMAP vma's
                 */
                vma = find_vma(walk->mm, addr);
-#ifdef CONFIG_HUGETLB_PAGE
-               if (vma && is_vm_hugetlb_page(vma)) {
-                       if (vma->vm_end < next)
+               if (vma) {
+                       /*
+                        * There are no page structures backing a VM_PFNMAP
+                        * range, so do not allow split_huge_page_pmd().
+                        */
+                       if ((vma->vm_start <= addr) &&
+                           (vma->vm_flags & VM_PFNMAP)) {
                                next = vma->vm_end;
+                               pgd = pgd_offset(walk->mm, next);
+                               continue;
+                       }
                        /*
-                        * Hugepage is very tightly coupled with vma, so
-                        * walk through hugetlb entries within a given vma.
+                        * Handle hugetlb vma individually because pagetable
+                        * walk for the hugetlb page is dependent on the
+                        * architecture and we can't handled it in the same
+                        * manner as non-huge pages.
                         */
-                       err = walk_hugetlb_range(vma, addr, next, walk);
-                       if (err)
-                               break;
-                       pgd = pgd_offset(walk->mm, next);
-                       continue;
+                       if (walk->hugetlb_entry && (vma->vm_start <= addr) &&
+                           is_vm_hugetlb_page(vma)) {
+                               if (vma->vm_end < next)
+                                       next = vma->vm_end;
+                               /*
+                                * Hugepage is very tightly coupled with vma,
+                                * so walk through hugetlb entries within a
+                                * given vma.
+                                */
+                               err = walk_hugetlb_range(vma, addr, next, walk);
+                               if (err)
+                                       break;
+                               pgd = pgd_offset(walk->mm, next);
+                               continue;
+                       }
                }
-#endif
+
                if (pgd_none_or_clear_bad(pgd)) {
                        if (walk->pte_hole)
                                err = walk->pte_hole(addr, next, walk);
@@ -188,7 +242,7 @@ int walk_page_range(unsigned long addr, unsigned long end,
                if (err)
                        break;
                pgd++;
-       } while (addr = next, addr != end);
+       } while (addr = next, addr < end);
 
        return err;
 }