[PATCH] Page migration: Fix vma flag checking

Currently we do not check for vma flags if sys_move_pages is called to move
individual pages.  If sys_migrate_pages is called to move pages then we
check for vm_flags that indicate a non migratable vma but that still
includes VM_LOCKED and we can migrate mlocked pages.

Extract the vma_migratable check from mm/mempolicy.c, fix it and put it
into migrate.h so that is can be used from both locations.

Problem was spotted by Lee Schermerhorn

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 9 insertions, 10 deletions

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 48148e0cdbd1..75e55dcdeb18 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -5,6 +5,14 @@
 
 typedef struct page *new_page_t(struct page *, unsigned long private, int **);
 
+/* Check if a vma is migratable */
+static inline int vma_migratable(struct vm_area_struct *vma)
+{
+        if (vma->vm_flags & (VM_IO|VM_HUGETLB|VM_PFNMAP|VM_RESERVED))
+                return 0;
+        return 1;
+}
+
 #ifdef CONFIG_MIGRATION
 extern int isolate_lru_page(struct page *p, struct list_head *pagelist);
 extern int putback_lru_pages(struct list_head *l);
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index cf2a5381030a..d76e8eb342d0 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -321,15 +321,6 @@ static inline int check_pgd_range(struct vm_area_struct *vma,
         return 0;
 }
 
-/* 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|VM_RESERVED))
-                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
diff --git a/mm/migrate.c b/mm/migrate.c
index e9b161bde95b..7a66ca25dc8a 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -781,7 +781,7 @@ static int do_move_pages(struct mm_struct *mm, struct page_to_node *pm,
 
                 err = -EFAULT;
                 vma = find_vma(mm, pp->addr);
-                if (!vma)
+                if (!vma || !vma_migratable(vma))
                         goto set_status;
 
                 page = follow_page(vma, pp->addr, FOLL_GET);