2 files changed, 138 insertions, 20 deletions

diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index ed00b278cb93..05443a766cb8 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -22,6 +22,9 @@
 
 /* Flags for mbind */
 #define MPOL_MF_STRICT  (1<<0)  /* Verify existing pages in the mapping */
+#define MPOL_MF_MOVE    (1<<1)  /* Move pages owned by this process to conform to mapping */
+#define MPOL_MF_MOVE_ALL (1<<2) /* Move every page to conform to mapping */
+#define MPOL_MF_INTERNAL (1<<3) /* Internal flags start here */
 
 #ifdef __KERNEL__
 
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 0f1d2b8a952b..9cc6d962831d 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -83,9 +83,14 @@
 #include <linux/init.h>
 #include <linux/compat.h>
 #include <linux/mempolicy.h>
+#include <linux/swap.h>
+
 #include <asm/tlbflush.h>
 #include <asm/uaccess.h>
 
+/* Internal MPOL_MF_xxx flags */
+#define MPOL_MF_DISCONTIG_OK (MPOL_MF_INTERNAL << 0)    /* Skip checks for continuous vmas */
+
 static kmem_cache_t *policy_cache;
 static kmem_cache_t *sn_cache;
 
@@ -174,9 +179,59 @@ static struct mempolicy *mpol_new(int mode, nodemask_t *nodes)
         return policy;
 }
 
+/* Check if we are the only process mapping the page in question */
+static inline int single_mm_mapping(struct mm_struct *mm,
+                        struct address_space *mapping)
+{
+        struct vm_area_struct *vma;
+        struct prio_tree_iter iter;
+        int rc = 1;
+
+        spin_lock(&mapping->i_mmap_lock);
+        vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
+                if (mm != vma->vm_mm) {
+                        rc = 0;
+                        goto out;
+                }
+        list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
+                if (mm != vma->vm_mm) {
+                        rc = 0;
+                        goto out;
+                }
+out:
+        spin_unlock(&mapping->i_mmap_lock);
+        return rc;
+}
+
+/*
+ * Add a page to be migrated to the pagelist
+ */
+static void migrate_page_add(struct vm_area_struct *vma,
+        struct page *page, struct list_head *pagelist, unsigned long flags)
+{
+        /*
+         * Avoid migrating a page that is shared by others and not writable.
+         */
+        if ((flags & MPOL_MF_MOVE_ALL) || !page->mapping || PageAnon(page) ||
+            mapping_writably_mapped(page->mapping) ||
+            single_mm_mapping(vma->vm_mm, page->mapping)) {
+                int rc = isolate_lru_page(page);
+
+                if (rc == 1)
+                        list_add(&page->lru, pagelist);
+                /*
+                 * If the isolate attempt was not successful then we just
+                 * encountered an unswappable page. Something must be wrong.
+                 */
+                WARN_ON(rc == 0);
+        }
+}
+
 /* Ensure all existing pages follow the policy. */
 static int check_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
-                unsigned long addr, unsigned long end, nodemask_t *nodes)
+                unsigned long addr, unsigned long end,
+                const nodemask_t *nodes, unsigned long flags,
+                struct list_head *pagelist)
 {
         pte_t *orig_pte;
         pte_t *pte;
@@ -193,15 +248,21 @@ static int check_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
                 if (!page)
                         continue;
                 nid = page_to_nid(page);
-                if (!node_isset(nid, *nodes))
-                        break;
+                if (!node_isset(nid, *nodes)) {
+                        if (pagelist)
+                                migrate_page_add(vma, page, pagelist, flags);
+                        else
+                                break;
+                }
         } while (pte++, addr += PAGE_SIZE, addr != end);
         pte_unmap_unlock(orig_pte, ptl);
         return addr != end;
 }
 
 static inline int check_pmd_range(struct vm_area_struct *vma, pud_t *pud,
-                unsigned long addr, unsigned long end, nodemask_t *nodes)
+                unsigned long addr, unsigned long end,
+                const nodemask_t *nodes, unsigned long flags,
+                struct list_head *pagelist)
 {
         pmd_t *pmd;
         unsigned long next;
@@ -211,14 +272,17 @@ static inline int check_pmd_range(struct vm_area_struct *vma, pud_t *pud,
                 next = pmd_addr_end(addr, end);
                 if (pmd_none_or_clear_bad(pmd))
                         continue;
-                if (check_pte_range(vma, pmd, addr, next, nodes))
+                if (check_pte_range(vma, pmd, addr, next, nodes,
+                                    flags, pagelist))
                         return -EIO;
         } while (pmd++, addr = next, addr != end);
         return 0;
 }
 
 static inline int check_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
-                unsigned long addr, unsigned long end, nodemask_t *nodes)
+                unsigned long addr, unsigned long end,
+                const nodemask_t *nodes, unsigned long flags,
+                struct list_head *pagelist)
 {
         pud_t *pud;
         unsigned long next;
@@ -228,14 +292,17 @@ static inline int check_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
                 next = pud_addr_end(addr, end);
                 if (pud_none_or_clear_bad(pud))
                         continue;
-                if (check_pmd_range(vma, pud, addr, next, nodes))
+                if (check_pmd_range(vma, pud, addr, next, nodes,
+                                    flags, pagelist))
                         return -EIO;
         } while (pud++, addr = next, addr != end);
         return 0;
 }
 
 static inline int check_pgd_range(struct vm_area_struct *vma,
-                unsigned long addr, unsigned long end, nodemask_t *nodes)
+                unsigned long addr, unsigned long end,
+                const nodemask_t *nodes, unsigned long flags,
+                struct list_head *pagelist)
 {
         pgd_t *pgd;
         unsigned long next;
@@ -245,16 +312,31 @@ static inline int check_pgd_range(struct vm_area_struct *vma,
                 next = pgd_addr_end(addr, end);
                 if (pgd_none_or_clear_bad(pgd))
                         continue;
-                if (check_pud_range(vma, pgd, addr, next, nodes))
+                if (check_pud_range(vma, pgd, addr, next, nodes,
+                                    flags, pagelist))
                         return -EIO;
         } while (pgd++, addr = next, addr != end);
         return 0;
 }
 
-/* Step 1: check the range */
+/* Check if a vma is migratable */
+static inline int vma_migratable(struct vm_area_struct *vma)
+{
+        if (vma->vm_flags & (
+                VM_LOCKED|VM_IO|VM_HUGETLB|VM_PFNMAP))
+                return 0;
+        return 1;
+}
+
+/*
+ * Check if all pages in a range are on a set of nodes.
+ * If pagelist != NULL then isolate pages from the LRU and
+ * put them on the pagelist.
+ */
 static struct vm_area_struct *
 check_range(struct mm_struct *mm, unsigned long start, unsigned long end,
-            nodemask_t *nodes, unsigned long flags)
+                const nodemask_t *nodes, unsigned long flags,
+                struct list_head *pagelist)
 {
         int err;
         struct vm_area_struct *first, *vma, *prev;
@@ -264,17 +346,24 @@ check_range(struct mm_struct *mm, unsigned long start, unsigned long end,
                 return ERR_PTR(-EFAULT);
         prev = NULL;
         for (vma = first; vma && vma->vm_start < end; vma = vma->vm_next) {
-                if (!vma->vm_next && vma->vm_end < end)
-                        return ERR_PTR(-EFAULT);
-                if (prev && prev->vm_end < vma->vm_start)
-                        return ERR_PTR(-EFAULT);
-                if ((flags & MPOL_MF_STRICT) && !is_vm_hugetlb_page(vma)) {
+                if (!(flags & MPOL_MF_DISCONTIG_OK)) {
+                        if (!vma->vm_next && vma->vm_end < end)
+                                return ERR_PTR(-EFAULT);
+                        if (prev && prev->vm_end < vma->vm_start)
+                                return ERR_PTR(-EFAULT);
+                }
+                if (!is_vm_hugetlb_page(vma) &&
+                    ((flags & MPOL_MF_STRICT) ||
+                     ((flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) &&
+                                vma_migratable(vma)))) {
                         unsigned long endvma = vma->vm_end;
+
                         if (endvma > end)
                                 endvma = end;
                         if (vma->vm_start > start)
                                 start = vma->vm_start;
-                        err = check_pgd_range(vma, start, endvma, nodes);
+                        err = check_pgd_range(vma, start, endvma, nodes,
+                                                flags, pagelist);
                         if (err) {
                                 first = ERR_PTR(err);
                                 break;
@@ -348,33 +437,59 @@ long do_mbind(unsigned long start, unsigned long len,
         struct mempolicy *new;
         unsigned long end;
         int err;
+        LIST_HEAD(pagelist);
 
-        if ((flags & ~(unsigned long)(MPOL_MF_STRICT)) || mode > MPOL_MAX)
+        if ((flags & ~(unsigned long)(MPOL_MF_STRICT|MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
+            || mode > MPOL_MAX)
                 return -EINVAL;
+        if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_RESOURCE))
+                return -EPERM;
+
         if (start & ~PAGE_MASK)
                 return -EINVAL;
+
         if (mode == MPOL_DEFAULT)
                 flags &= ~MPOL_MF_STRICT;
+
         len = (len + PAGE_SIZE - 1) & PAGE_MASK;
         end = start + len;
+
         if (end < start)
                 return -EINVAL;
         if (end == start)
                 return 0;
+
         if (mpol_check_policy(mode, nmask))
                 return -EINVAL;
+
         new = mpol_new(mode, nmask);
         if (IS_ERR(new))
                 return PTR_ERR(new);
 
+        /*
+         * If we are using the default policy then operation
+         * on discontinuous address spaces is okay after all
+         */
+        if (!new)
+                flags |= MPOL_MF_DISCONTIG_OK;
+
         PDprintk("mbind %lx-%lx mode:%ld nodes:%lx\n",start,start+len,
                         mode,nodes_addr(nodes)[0]);
 
         down_write(&mm->mmap_sem);
-        vma = check_range(mm, start, end, nmask, flags);
+        vma = check_range(mm, start, end, nmask, flags,
+              (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) ? &pagelist : NULL);
         err = PTR_ERR(vma);
-        if (!IS_ERR(vma))
+        if (!IS_ERR(vma)) {
                 err = mbind_range(vma, start, end, new);
+                if (!list_empty(&pagelist))
+                        migrate_pages(&pagelist, NULL);
+                if (!err && !list_empty(&pagelist) && (flags & MPOL_MF_STRICT))
+                        err = -EIO;
+        }
+        if (!list_empty(&pagelist))
+                putback_lru_pages(&pagelist);
+
         up_write(&mm->mmap_sem);
         mpol_free(new);
         return err;