diff options
| author | Tejun Heo <tj@kernel.org> | 2020-01-30 11:37:33 -0500 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2020-01-30 11:37:33 -0500 |
| commit | 0cd9d33ace336bc424fc30944aa3defd6786e4fe (patch) | |
| tree | eb96a2a3b8d55ecd4c96741eefd766c9d86c68e7 | |
| parent | 39bed42de2e7d74686a2d5a45638d6a5d7e7d473 (diff) | |
cgroup: init_tasks shouldn't be linked to the root cgroup
5153faac18d2 ("cgroup: remove cgroup_enable_task_cg_lists()
optimization") removed lazy initialization of css_sets so that new
tasks are always lniked to its css_set. In the process, it incorrectly
ended up adding init_tasks to root css_set. They show up as PID 0's in
root's cgroup.procs triggering warnings in systemd and generally
confusing people.
Fix it by skip css_set linking for init_tasks.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: https://github.com/joanbm
Link: https://github.com/systemd/systemd/issues/14682
Fixes: 5153faac18d2 ("cgroup: remove cgroup_enable_task_cg_lists() optimization")
Cc: stable@vger.kernel.org # v5.5+
| -rw-r--r-- | kernel/cgroup/cgroup.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index b3744872263e..cf8a36bdf5c8 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -5932,11 +5932,14 @@ void cgroup_post_fork(struct task_struct *child) spin_lock_irq(&css_set_lock); - WARN_ON_ONCE(!list_empty(&child->cg_list)); - cset = task_css_set(current); /* current is @child's parent */ - get_css_set(cset); - cset->nr_tasks++; - css_set_move_task(child, NULL, cset, false); + /* init tasks are special, only link regular threads */ + if (likely(child->pid)) { + WARN_ON_ONCE(!list_empty(&child->cg_list)); + cset = task_css_set(current); /* current is @child's parent */ + get_css_set(cset); + cset->nr_tasks++; + css_set_move_task(child, NULL, cset, false); + } /* * If the cgroup has to be frozen, the new task has too. Let's set |