1 files changed, 11 insertions, 6 deletions

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 143b019e983..3c8ee31572e 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1965,6 +1965,11 @@ static inline int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
         unsigned short mode;
         unsigned short flags = pol ? pol->flags : 0;
 
+        /*
+         * Sanity check:  room for longest mode, flag and some nodes
+         */
+        VM_BUG_ON(maxlen < strlen("interleave") + strlen("relative") + 16);
+
         if (!pol || pol == &default_policy)
                 mode = MPOL_DEFAULT;
         else
@@ -1991,7 +1996,6 @@ static inline int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
 
         default:
                 BUG();
-                return -EFAULT;
         }
 
         l = strlen(policy_types[mode]);
@@ -2002,16 +2006,17 @@ static inline int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
         p += l;
 
         if (flags & MPOL_MODE_FLAGS) {
-                int need_bar = 0;
-
                 if (buffer + maxlen < p + 2)
                         return -ENOSPC;
                 *p++ = '=';
 
+                /*
+                 * Currently, the only defined flags are mutually exclusive
+                 */
                 if (flags & MPOL_F_STATIC_NODES)
-                        p += sprintf(p, "%sstatic", need_bar++ ? "|" : "");
-                if (flags & MPOL_F_RELATIVE_NODES)
-                        p += sprintf(p, "%srelative", need_bar++ ? "|" : "");
+                        p += snprintf(p, buffer + maxlen - p, "static");
+                else if (flags & MPOL_F_RELATIVE_NODES)
+                        p += snprintf(p, buffer + maxlen - p, "relative");
         }
 
         if (!nodes_empty(nodes)) {