Re: [PATCH v3 6/6] freezer,sched: Rewrite core freezer logic

Peter Zijlstra
2022-09-26T14:37:32Z

On Mon, Sep 26, 2022 at 02:32:24PM +0200, Christian Borntraeger wrote:
> diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
> index 9fa3c76a267f..e93df4f735fe 100644
> --- a/drivers/char/virtio_console.c
> +++ b/drivers/char/virtio_console.c
> @@ -790,7 +790,7 @@ static int wait_port_writable(struct port *port, bool nonblock)
> if (nonblock)
> return -EAGAIN;
> - ret = wait_event_freezable(port->waitqueue,
> + ret = wait_event_interruptible(port->waitqueue,
> !will_write_block(port));
> if (ret < 0)
> return ret;
>
> Does fix the problem.

It's almost as if someone does try_to_wake_up(.state = TASK_FREEZABLE)
-- which would be quite insane.

Could you please test with something like the below on? I can boot that
with KVM, but obviously I didn't suffer any weirdness to begin with :/

---
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 4e6a6417211f..ef9ccfc3a8c0 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4051,6 +4051,8 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
unsigned long flags;
int cpu, success = 0;

+ WARN_ON_ONCE(state & TASK_FREEZABLE);
+
preempt_disable();
if (p == current) {
/*