Tejun Heo (tj@kernel.org) wrote:

Hello,

On Tue, Dec 20, 2011 at 03:14:32PM -0800, Mandeep Singh Baines wrote:

quoted

@@ -1942,9 +1917,17 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
 		}
 	}
 
-	retval = cgroup_task_migrate(cgrp, oldcgrp, tsk, false);
-	if (retval)
+	task_lock(tsk);
+	oldcg = tsk->cgroups;
+	task_unlock(tsk);

Probably this is patch order issue w/ Frederic's patch but we don't
need task_lock here, right?

Yeah, avoided removing the locks because Frederic's patch already did that.
Once his changes get in, I'll rebase and resend.

quoted

@@ -2171,17 +2088,18 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
 	 * step 2: make sure css_sets exist for all threads to be migrated.
 	 * we use find_css_set, which allocates a new one if necessary.
 	 */
-	INIT_LIST_HEAD(&newcg_list);
 	for (i = 0; i < group_size; i++) {
 		tc = flex_array_get(group, i);
 		/* get old css_set pointer */
 		task_lock(tc->task);
 		oldcg = tc->task->cgroups;
 		task_unlock(tc->task);
-		/* if we don't already have it in the list get a new one */
-		if (!css_set_fetched(cgrp, tc->task, oldcg, &newcg_list))
-			if (retval = css_set_prefetch(cgrp, oldcg, &newcg_list))
-				goto out_list_teardown;
+		tc->cg = find_css_set(oldcg, cgrp);
+		if (!tc->cg) {
+			retval = -ENOMEM;
+			css_set_refs = i + 1;
+			goto out_list_teardown;
+		}

Nice cleanup, but can't the above be merged into the loop which builds
the flex array?

Good idea. That would remove a for loop. Will fix in next version.

Thanks.

-- 
tejun