mm: optimize put_mems_allowed() usage

[platform/adaptation/renesas_rcar/renesas_kernel.git] / kernel / cpuset.c

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 4410ac6..15b3ea6 100644 (file)
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -974,12 +974,6 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
  *    Temporarilly set tasks mems_allowed to target nodes of migration,
  *    so that the migration code can allocate pages on these nodes.
  *
- *    Call holding cpuset_mutex, so current's cpuset won't change
- *    during this call, as manage_mutex holds off any cpuset_attach()
- *    calls.  Therefore we don't need to take task_lock around the
- *    call to guarantee_online_mems(), as we know no one is changing
- *    our task's cpuset.
- *
  *    While the mm_struct we are migrating is typically from some
  *    other task, the task_struct mems_allowed that we are hacking
  *    is for our current task, which must allocate new pages for that
@@ -996,8 +990,10 @@ static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
 
        do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL);
 
+       rcu_read_lock();
        mems_cs = effective_nodemask_cpuset(task_cs(tsk));
        guarantee_online_mems(mems_cs, &tsk->mems_allowed);
+       rcu_read_unlock();
 }
 
 /*
@@ -1026,7 +1022,7 @@ static void cpuset_change_task_nodemask(struct task_struct *tsk,
        task_lock(tsk);
        /*
         * Determine if a loop is necessary if another thread is doing
-        * get_mems_allowed().  If at least one node remains unchanged and
+        * read_mems_allowed_begin().  If at least one node remains unchanged and
         * tsk does not have a mempolicy, then an empty nodemask will not be
         * possible when mems_allowed is larger than a word.
         */
@@ -1240,7 +1236,13 @@ done:
 
 int current_cpuset_is_being_rebound(void)
 {
-       return task_cs(current) == cpuset_being_rebound;
+       int ret;
+
+       rcu_read_lock();
+       ret = task_cs(current) == cpuset_being_rebound;
+       rcu_read_unlock();
+
+       return ret;
 }
 
 static int update_relax_domain_level(struct cpuset *cs, s64 val)
@@ -2486,9 +2488,9 @@ int __cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
 
        task_lock(current);
        cs = nearest_hardwall_ancestor(task_cs(current));
+       allowed = node_isset(node, cs->mems_allowed);
        task_unlock(current);
 
-       allowed = node_isset(node, cs->mems_allowed);
        mutex_unlock(&callback_mutex);
        return allowed;
 }