Re: [PATCH] vhost: Take a reference on the task that is reference in struct vhost_task.

[Sean Christopherson]

On Thu, Sep 18, 2025, Sebastian Andrzej Siewior wrote:
> vhost_task_create() creates a task and keeps a reference to its
> task_struct. That task may exit early via a signal and its task_struct
> will be released.
> A pending vhost_task_wake() will then attempt to wake the task and
> access a task_struct which is no longer there.
> 
> Acquire a reference on the task_struct while creating the thread and
> release the reference while the struct vhost_task itself is removed.
> If the task exits early due to a signal, then the vhost_task_wake() will
> still access a valid task_struct. The wake is safe and will be skipped
> in this case.
> 
> Fixes: f9010dbdce911 ("fork, vhost: Use CLONE_THREAD to fix freezer/ps regression")
> Reported-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> Closes: https://lore.kernel.org/all/aKkLEtoDXKxAAWju@xxxxxxxxxx/
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> ---

Tested-by: Sean Christopherson <seanjc@xxxxxxxxxx>