vmalloc: unmap vmalloc area after hiding it

vmap area should be purged after vm_struct is removed from the list
because vread/vwrite etc...believes the range is valid while it's on
vm_struct list.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Mike Smith <scgtrp@gmail.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 5 deletions

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 759deae4539a..c4071fa8e12a 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1270,17 +1270,21 @@ struct vm_struct *remove_vm_area(const void *addr)
         if (va && va->flags & VM_VM_AREA) {
                 struct vm_struct *vm = va->private;
                 struct vm_struct *tmp, **p;
-
-                vmap_debug_free_range(va->va_start, va->va_end);
-                free_unmap_vmap_area(va);
-                vm->size -= PAGE_SIZE;
-
+                /*
+                 * remove from list and disallow access to this vm_struct
+                 * before unmap. (address range confliction is maintained by
+                 * vmap.)
+                 */
                 write_lock(&vmlist_lock);
                 for (p = &vmlist; (tmp = *p) != vm; p = &tmp->next)
                         ;
                 *p = tmp->next;
                 write_unlock(&vmlist_lock);
 
+                vmap_debug_free_range(va->va_start, va->va_end);
+                free_unmap_vmap_area(va);
+                vm->size -= PAGE_SIZE;
+
                 return vm;
         }
         return NULL;