[PATCH] fix mempolicy's check on a system with memory-less-node

bind_zonelist() can create zero-length zonelist if there is a
memory-less-node.  This patch checks the length of zonelist.  If length is
0, returns -EINVAL.

tested on ia64/NUMA with memory-less-node.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Andi Kleen <ak@suse.de>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 259a706..cf2a538 100644 (file)
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -144,7 +144,7 @@ static struct zonelist *bind_zonelist(nodemask_t *nodes)
        max++;                  /* space for zlcache_ptr (see mmzone.h) */
        zl = kmalloc(sizeof(struct zone *) * max, GFP_KERNEL);
        if (!zl)
-               return NULL;
+               return ERR_PTR(-ENOMEM);
        zl->zlcache_ptr = NULL;
        num = 0;
        /* First put in the highest zones from all nodes, then all the next 
@@ -162,6 +162,10 @@ static struct zonelist *bind_zonelist(nodemask_t *nodes)
                        break;
                k--;
        }
+       if (num == 0) {
+               kfree(zl);
+               return ERR_PTR(-EINVAL);
+       }
        zl->zones[num] = NULL;
        return zl;
 }
@@ -193,9 +197,10 @@ static struct mempolicy *mpol_new(int mode, nodemask_t *nodes)
                break;
        case MPOL_BIND:
                policy->v.zonelist = bind_zonelist(nodes);
-               if (policy->v.zonelist == NULL) {
+               if (IS_ERR(policy->v.zonelist)) {
+                       void *error_code = policy->v.zonelist;
                        kmem_cache_free(policy_cache, policy);
-                       return ERR_PTR(-ENOMEM);
+                       return error_code;
                }
                break;
        }
@@ -1667,7 +1672,7 @@ void mpol_rebind_policy(struct mempolicy *pol, const nodemask_t *newmask)
                 * then zonelist_policy() will "FALL THROUGH" to MPOL_DEFAULT.
                 */
 
-               if (zonelist) {
+               if (!IS_ERR(zonelist)) {
                        /* Good - got mem - substitute new zonelist */
                        kfree(pol->v.zonelist);
                        pol->v.zonelist = zonelist;