cpuset: alloc nodemask_t on the heap rather than the stack

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 66 insertions, 28 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 5d38bd74483c..d10946748ec2 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -970,15 +970,20 @@ static void cpuset_change_nodemask(struct task_struct *p,
         struct cpuset *cs;
         int migrate;
         const nodemask_t *oldmem = scan->data;
-        nodemask_t newmems;
+        NODEMASK_ALLOC(nodemask_t, newmems, GFP_KERNEL);
+
+        if (!newmems)
+                return;
 
         cs = cgroup_cs(scan->cg);
-        guarantee_online_mems(cs, &newmems);
+        guarantee_online_mems(cs, newmems);
 
         task_lock(p);
-        cpuset_change_task_nodemask(p, &newmems);
+        cpuset_change_task_nodemask(p, newmems);
         task_unlock(p);
 
+        NODEMASK_FREE(newmems);
+
         mm = get_task_mm(p);
         if (!mm)
                 return;
@@ -1048,16 +1053,21 @@ static void update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem,
 static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
                            const char *buf)
 {
-        nodemask_t oldmem;
+        NODEMASK_ALLOC(nodemask_t, oldmem, GFP_KERNEL);
         int retval;
         struct ptr_heap heap;
 
+        if (!oldmem)
+                return -ENOMEM;
+
         /*
          * top_cpuset.mems_allowed tracks node_stats[N_HIGH_MEMORY];
          * it's read-only
          */
-        if (cs == &top_cpuset)
-                return -EACCES;
+        if (cs == &top_cpuset) {
+                retval = -EACCES;
+                goto done;
+        }
 
         /*
          * An empty mems_allowed is ok iff there are no tasks in the cpuset.
@@ -1073,11 +1083,13 @@ static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
                         goto done;
 
                 if (!nodes_subset(trialcs->mems_allowed,
-                                node_states[N_HIGH_MEMORY]))
-                        return -EINVAL;
+                                node_states[N_HIGH_MEMORY])) {
+                        retval =  -EINVAL;
+                        goto done;
+                }
         }
-        oldmem = cs->mems_allowed;
-        if (nodes_equal(oldmem, trialcs->mems_allowed)) {
+        *oldmem = cs->mems_allowed;
+        if (nodes_equal(*oldmem, trialcs->mems_allowed)) {
                 retval = 0;             /* Too easy - nothing to do */
                 goto done;
         }
@@ -1093,10 +1105,11 @@ static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
         cs->mems_allowed = trialcs->mems_allowed;
         mutex_unlock(&callback_mutex);
 
-        update_tasks_nodemask(cs, &oldmem, &heap);
+        update_tasks_nodemask(cs, oldmem, &heap);
 
         heap_free(&heap);
 done:
+        NODEMASK_FREE(oldmem);
         return retval;
 }
 
@@ -1381,39 +1394,47 @@ static void cpuset_attach(struct cgroup_subsys *ss, struct cgroup *cont,
                           struct cgroup *oldcont, struct task_struct *tsk,
                           bool threadgroup)
 {
-        nodemask_t from, to;
         struct mm_struct *mm;
         struct cpuset *cs = cgroup_cs(cont);
         struct cpuset *oldcs = cgroup_cs(oldcont);
+        NODEMASK_ALLOC(nodemask_t, from, GFP_KERNEL);
+        NODEMASK_ALLOC(nodemask_t, to, GFP_KERNEL);
+
+        if (from == NULL || to == NULL)
+                goto alloc_fail;
 
         if (cs == &top_cpuset) {
                 cpumask_copy(cpus_attach, cpu_possible_mask);
         } else {
                 guarantee_online_cpus(cs, cpus_attach);
         }
-        guarantee_online_mems(cs, &to);
+        guarantee_online_mems(cs, to);
 
         /* do per-task migration stuff possibly for each in the threadgroup */
-        cpuset_attach_task(tsk, &to, cs);
+        cpuset_attach_task(tsk, to, cs);
         if (threadgroup) {
                 struct task_struct *c;
                 rcu_read_lock();
                 list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) {
-                        cpuset_attach_task(c, &to, cs);
+                        cpuset_attach_task(c, to, cs);
                 }
                 rcu_read_unlock();
         }
 
         /* change mm; only needs to be done once even if threadgroup */
-        from = oldcs->mems_allowed;
-        to = cs->mems_allowed;
+        *from = oldcs->mems_allowed;
+        *to = cs->mems_allowed;
         mm = get_task_mm(tsk);
         if (mm) {
-                mpol_rebind_mm(mm, &to);
+                mpol_rebind_mm(mm, to);
                 if (is_memory_migrate(cs))
-                        cpuset_migrate_mm(mm, &from, &to);
+                        cpuset_migrate_mm(mm, from, to);
                 mmput(mm);
         }
+
+alloc_fail:
+        NODEMASK_FREE(from);
+        NODEMASK_FREE(to);
 }
 
 /* The various types of files and directories in a cpuset file system */
@@ -1558,13 +1579,21 @@ static int cpuset_sprintf_cpulist(char *page, struct cpuset *cs)
 
 static int cpuset_sprintf_memlist(char *page, struct cpuset *cs)
 {
-        nodemask_t mask;
+        NODEMASK_ALLOC(nodemask_t, mask, GFP_KERNEL);
+        int retval;
+
+        if (mask == NULL)
+                return -ENOMEM;
 
         mutex_lock(&callback_mutex);
-        mask = cs->mems_allowed;
+        *mask = cs->mems_allowed;
         mutex_unlock(&callback_mutex);
 
-        return nodelist_scnprintf(page, PAGE_SIZE, mask);
+        retval = nodelist_scnprintf(page, PAGE_SIZE, *mask);
+
+        NODEMASK_FREE(mask);
+
+        return retval;
 }
 
 static ssize_t cpuset_common_file_read(struct cgroup *cont,
@@ -1993,7 +2022,10 @@ static void scan_for_empty_cpusets(struct cpuset *root)
         struct cpuset *cp;      /* scans cpusets being updated */
         struct cpuset *child;   /* scans child cpusets of cp */
         struct cgroup *cont;
-        nodemask_t oldmems;
+        NODEMASK_ALLOC(nodemask_t, oldmems, GFP_KERNEL);
+
+        if (oldmems == NULL)
+                return;
 
         list_add_tail((struct list_head *)&root->stack_list, &queue);
 
@@ -2010,7 +2042,7 @@ static void scan_for_empty_cpusets(struct cpuset *root)
                     nodes_subset(cp->mems_allowed, node_states[N_HIGH_MEMORY]))
                         continue;
 
-                oldmems = cp->mems_allowed;
+                *oldmems = cp->mems_allowed;
 
                 /* Remove offline cpus and mems from this cpuset. */
                 mutex_lock(&callback_mutex);
@@ -2026,9 +2058,10 @@ static void scan_for_empty_cpusets(struct cpuset *root)
                         remove_tasks_in_empty_cpuset(cp);
                 else {
                         update_tasks_cpumask(cp, NULL);
-                        update_tasks_nodemask(cp, &oldmems, NULL);
+                        update_tasks_nodemask(cp, oldmems, NULL);
                 }
         }
+        NODEMASK_FREE(oldmems);
 }
 
 /*
@@ -2086,16 +2119,19 @@ static int cpuset_track_online_cpus(struct notifier_block *unused_nb,
 static int cpuset_track_online_nodes(struct notifier_block *self,
                                 unsigned long action, void *arg)
 {
-        nodemask_t oldmems;
+        NODEMASK_ALLOC(nodemask_t, oldmems, GFP_KERNEL);
+
+        if (oldmems == NULL)
+                return NOTIFY_DONE;
 
         cgroup_lock();
         switch (action) {
         case MEM_ONLINE:
-                oldmems = top_cpuset.mems_allowed;
+                *oldmems = top_cpuset.mems_allowed;
                 mutex_lock(&callback_mutex);
                 top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
                 mutex_unlock(&callback_mutex);
-                update_tasks_nodemask(&top_cpuset, &oldmems, NULL);
+                update_tasks_nodemask(&top_cpuset, oldmems, NULL);
                 break;
         case MEM_OFFLINE:
                 /*
@@ -2108,6 +2144,8 @@ static int cpuset_track_online_nodes(struct notifier_block *self,
                 break;
         }
         cgroup_unlock();
+
+        NODEMASK_FREE(oldmems);
         return NOTIFY_OK;
 }
 #endif