diff options
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index c02b05560d10..589433f7a74b 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4277,6 +4277,7 @@ static int cgroup_destroy_locked(struct cgroup *cgrp) DEFINE_WAIT(wait); struct cgroup_event *event, *tmp; struct cgroup_subsys *ss; + LIST_HEAD(tmp_list); lockdep_assert_held(&d->d_inode->i_mutex); lockdep_assert_held(&cgroup_mutex); @@ -4331,16 +4332,20 @@ static int cgroup_destroy_locked(struct cgroup *cgrp) /* * Unregister events and notify userspace. * Notify userspace about cgroup removing only after rmdir of cgroup - * directory to avoid race between userspace and kernelspace + * directory to avoid race between userspace and kernelspace. Use + * a temporary list to avoid a deadlock with cgroup_event_wake(). Since + * cgroup_event_wake() is called with the wait queue head locked, + * remove_wait_queue() cannot be called while holding event_list_lock. */ spin_lock(&cgrp->event_list_lock); - list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) { + list_splice_init(&cgrp->event_list, &tmp_list); + spin_unlock(&cgrp->event_list_lock); + list_for_each_entry_safe(event, tmp, &tmp_list, list) { list_del(&event->list); remove_wait_queue(event->wqh, &event->wait); eventfd_signal(event->eventfd, 1); schedule_work(&event->remove); } - spin_unlock(&cgrp->event_list_lock); return 0; } |