Merge branch 'cgroup/for-3.14-fixes' into cgroup/for-3.15

Pull in for-3.14-fixes to receive 532de3fc72ad ("cgroup: update
cgroup_enable_task_cg_lists() to grab siglock") which conflicts with
afeb0f9fd425 ("cgroup: relocate cgroup_enable_task_cg_lists()") and
the following cg_lists updates.  This is likely to cause further
conflicts down the line too, so let's merge it early.

As cgroup_enable_task_cg_lists() is relocated in for-3.15, this merge
causes conflict in the original position.  It's resolved by applying
siglock changes to the updated version in the new location.

Conflicts:
	kernel/cgroup.c

Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 771d1b8aaae98bd9e980b79dc838905e3f023a48..8ab800c7bac0ef79328e739bda3837351b797112 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1331,9 +1331,13 @@ static void cgroup_enable_task_cg_lists(void)
                 * We should check if the process is exiting, otherwise
                 * it will race with cgroup_exit() in that the list
                 * entry won't be deleted though the process has exited.
+                * Do it while holding siglock so that we don't end up
+                * racing against cgroup_exit().
                 */
+               spin_lock_irq(&p->sighand->siglock);
                if (!(p->flags & PF_EXITING))
                        list_add(&p->cg_list, &task_css_set(p)->tasks);
+               spin_unlock_irq(&p->sighand->siglock);
 
                task_unlock(p);
        } while_each_thread(g, p);
@@ -3968,16 +3972,12 @@ static int __init cgroup_wq_init(void)
        /*
         * There isn't much point in executing destruction path in
         * parallel.  Good chunk is serialized with cgroup_mutex anyway.
-        *
-        * XXX: Must be ordered to make sure parent is offlined after
-        * children.  The ordering requirement is for memcg where a
-        * parent's offline may wait for a child's leading to deadlock.  In
-        * the long term, this should be fixed from memcg side.
+        * Use 1 for @max_active.
         *
         * We would prefer to do this in cgroup_init() above, but that
         * is called before init_workqueues(): so leave this until after.
         */
-       cgroup_destroy_wq = alloc_ordered_workqueue("cgroup_destroy", 0);
+       cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1);
        BUG_ON(!cgroup_destroy_wq);
 
        /*