cpuset: remove unneeded NODEMASK_ALLOC() in cpuset_sprintf_memlist()

It's not necessary to copy cpuset->mems_allowed to a buffer allocated by
NODEMASK_ALLOC().  Just pass it to nodelist_scnprintf().

As spotted by Paul, a side effect is we fix a bug that the function can
return -ENOMEM but the caller doesn't expect negative return value.
Therefore change the return value of cpuset_sprintf_cpulist() and
cpuset_sprintf_memlist() from int to size_t.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NPaul Menage <menage@google.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

kernel/cpuset.c

@@ -1610,34 +1610,26 @@ static int cpuset_write_resmask(struct cgroup *cgrp, struct cftype *cft,
  * across a page fault.
  */
 
-static int cpuset_sprintf_cpulist(char *page, struct cpuset *cs)
+static size_t cpuset_sprintf_cpulist(char *page, struct cpuset *cs)
 {
-	int ret;
+	size_t count;
 
 	mutex_lock(&callback_mutex);
-	ret = cpulist_scnprintf(page, PAGE_SIZE, cs->cpus_allowed);
+	count = cpulist_scnprintf(page, PAGE_SIZE, cs->cpus_allowed);
 	mutex_unlock(&callback_mutex);
 
-	return ret;
+	return count;
 }
 
-static int cpuset_sprintf_memlist(char *page, struct cpuset *cs)
+static size_t cpuset_sprintf_memlist(char *page, struct cpuset *cs)
 {
-	NODEMASK_ALLOC(nodemask_t, mask, GFP_KERNEL);
-	int retval;
-
-	if (mask == NULL)
-		return -ENOMEM;
+	size_t count;
 
 	mutex_lock(&callback_mutex);
-	*mask = cs->mems_allowed;
+	count = nodelist_scnprintf(page, PAGE_SIZE, cs->mems_allowed);
 	mutex_unlock(&callback_mutex);
 
-	retval = nodelist_scnprintf(page, PAGE_SIZE, *mask);
-
-	NODEMASK_FREE(mask);
-
-	return retval;
+	return count;
 }
 
 static ssize_t cpuset_common_file_read(struct cgroup *cont,