Re: [PATCH] vfio/pci: Drain eventfd RCU callbacks on module exit

[Alex Williamson <alex@shazbot.org>]

On Sat,  3 Oct 2026 17:38:06 +0800
Jiale Yao <yaojiale02@163.com> wrote:

> vfio_pci_eventfd_replace_locked() defers freeing replaced eventfds to
> vfio_pci_eventfd_rcu_free(). A callback can remain queued after
> close_device() returns and the device driver module reference is dropped.
> Once the dependent driver is removed, vfio-pci-core can be unloaded while
> the callback still points into its module text.
> 
> Wait for outstanding RCU callbacks before vfio-pci-core exits.
> 
> Fixes: 98693e0897f7 ("vfio/pci: Use RCU for error/request triggers to avoid circular locking")
> Signed-off-by: Jiale Yao <yaojiale02@163.com>
> ---
>  drivers/vfio/pci/vfio_pci_core.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
> index 6757054e9d87..9bce419c52c8 100644
> --- a/drivers/vfio/pci/vfio_pci_core.c
> +++ b/drivers/vfio/pci/vfio_pci_core.c
> @@ -2675,6 +2675,7 @@ static void vfio_pci_dev_set_try_reset(struct vfio_device_set *dev_set)
>  static void vfio_pci_core_cleanup(void)
>  {
>  	vfio_pci_uninit_perm_bits();
> +	rcu_barrier();
>  }
>  
>  static int __init vfio_pci_core_init(void)

Applied to vfio next branch for v7.4.  Thanks,

Alex