diff options
| author | Roman Gushchin <guro@fb.com> | 2019-04-26 19:59:45 +0200 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2019-05-06 17:39:11 +0200 |
| commit | 96b9c592def5d7203bdad1337d9c92a2183de5cb (patch) | |
| tree | e7e9f4f31aa3c2182de25d660aba59cf3325d4cd /kernel/cgroup | |
| parent | cgroup: prevent spurious transition into non-frozen state (diff) | |
| download | linux-96b9c592def5d7203bdad1337d9c92a2183de5cb.tar.xz linux-96b9c592def5d7203bdad1337d9c92a2183de5cb.zip | |
cgroup: get rid of cgroup_freezer_frozen_exit()
A task should never enter the exit path with the task->frozen bit set.
Any frozen task must enter the signal handling loop and the only
way to escape is through cgroup_leave_frozen(true), which
unconditionally drops the task->frozen bit. So it means that
cgroyp_freezer_frozen_exit() has zero chances to be called and
has to be removed.
Let's put a WARN_ON_ONCE() instead of the cgroup_freezer_frozen_exit()
call to catch any potential leak of the task's frozen bit.
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/cgroup')
| -rw-r--r-- | kernel/cgroup/cgroup.c | 5 | ||||
| -rw-r--r-- | kernel/cgroup/freezer.c | 10 |
2 files changed, 2 insertions, 13 deletions
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 4fe9f7f1a3fa..327f37c9fdfa 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -5926,9 +5926,8 @@ void cgroup_exit(struct task_struct *tsk) css_set_move_task(tsk, cset, NULL, false); cset->nr_tasks--; - if (unlikely(cgroup_task_frozen(tsk))) - cgroup_freezer_frozen_exit(tsk); - else if (unlikely(cgroup_task_freeze(tsk))) + WARN_ON_ONCE(cgroup_task_frozen(tsk)); + if (unlikely(cgroup_task_freeze(tsk))) cgroup_update_frozen(task_dfl_cgroup(tsk)); spin_unlock_irq(&css_set_lock); diff --git a/kernel/cgroup/freezer.c b/kernel/cgroup/freezer.c index c321e768f8d3..8cf010680678 100644 --- a/kernel/cgroup/freezer.c +++ b/kernel/cgroup/freezer.c @@ -248,16 +248,6 @@ void cgroup_freezer_migrate_task(struct task_struct *task, cgroup_freeze_task(task, test_bit(CGRP_FREEZE, &dst->flags)); } -void cgroup_freezer_frozen_exit(struct task_struct *task) -{ - struct cgroup *cgrp = task_dfl_cgroup(task); - - lockdep_assert_held(&css_set_lock); - - cgroup_dec_frozen_cnt(cgrp); - cgroup_update_frozen(cgrp); -} - void cgroup_freeze(struct cgroup *cgrp, bool freeze) { struct cgroup_subsys_state *css; |