diff options
| author | Roman Gushchin <guro@fb.com> | 2019-04-26 10:59:44 -0700 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2019-05-06 08:39:06 -0700 |
| commit | cb2c4cd87874a7975b7b8615866b3a87bae10aab (patch) | |
| tree | 306f73b6b4208a222e4e8e3902d5de62668eb5cb /kernel/signal.c | |
| parent | 533307dc20a9e84a0687d4ca24aeb669516c0243 (diff) | |
cgroup: prevent spurious transition into non-frozen state
If freezing of a cgroup races with waking of a task from
the frozen state (like waiting in vfork() or in do_signal_stop()),
a spurious transition of the cgroup state can happen.
The task enters cgroup_leave_frozen(true), the cgroup->nr_frozen_tasks
counter decrements, and the cgroup is switched to the unfrozen state.
To prevent it, let's reserve cgroup_leave_frozen(true) for
terminating processes and use cgroup_leave_frozen(false) otherwise.
To avoid busy-looping in the signal handling loop waiting
for JOBCTL_TRAP_FREEZE set from the cgroup freezing path,
let's do it explicitly in cgroup_leave_frozen(), if the task
is going to stay frozen.
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/signal.c')
| -rw-r--r-- | kernel/signal.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index 095e0fc57b25..16b72f4f14df 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2514,7 +2514,7 @@ relock: */ if (unlikely(cgroup_task_frozen(current))) { spin_unlock_irq(&sighand->siglock); - cgroup_leave_frozen(true); + cgroup_leave_frozen(false); goto relock; } |