On Sun, Sep 21, 2025 at 04:56:20PM -0400, Michael S. Tsirkin wrote:
> Subject: that is reference -> that is referenced
to note i fixed it for now. just dropped "that is referenced"
completely. shorter.
> On Thu, Sep 18, 2025 at 08:11:44PM +0200, 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 <[email protected]>
> > Closes: https://lore.kernel.org/all/[email protected]/
> > Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
> > ---
> > kernel/vhost_task.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/kernel/vhost_task.c b/kernel/vhost_task.c
> > index bc738fa90c1d6..27107dcc1cbfe 100644
> > --- a/kernel/vhost_task.c
> > +++ b/kernel/vhost_task.c
> > @@ -100,6 +100,7 @@ void vhost_task_stop(struct vhost_task *vtsk)
> > * freeing it below.
> > */
> > wait_for_completion(&vtsk->exited);
> > + put_task_struct(vtsk->task);
> > kfree(vtsk);
> > }
> > EXPORT_SYMBOL_GPL(vhost_task_stop);
> > @@ -148,7 +149,7 @@ struct vhost_task *vhost_task_create(bool (*fn)(void *),
> > return ERR_CAST(tsk);
> > }
> >
> > - vtsk->task = tsk;
> > + vtsk->task = get_task_struct(tsk);
> > return vtsk;
> > }
> > EXPORT_SYMBOL_GPL(vhost_task_create);
> > --
> > 2.51.0
