Re: [PATCH net-next] r8152: use GFP_NOIO during system suspend

[Andrew Lunn <andrew@lunn.ch>]

On Mon, Aug 10, 2026 at 02:57:41PM +0800, Chih Kai Hsu wrote:
> During system suspend, memory allocation with GFP_KERNEL can block
> waiting for I/O to complete. If that I/O depends on a device that is
> itself suspended, a deadlock results.
> 
> Introduce RTL8152_SYSTEM_SUSPEND flag to track when the driver is
> operating in the system suspend/resume context. Set the flag at the
> start of rtl8152_system_suspend() and clear it at the end of
> rtl8152_system_resume(), following the same pattern used by
> SELECTIVE_SUSPEND for runtime suspend.
> 
> In get_registers() and set_registers(), select GFP_NOIO when the flag
> is set so that the kmalloc and kmemdup calls in those paths do not
> trigger I/O reclaim.

Do you have a reproducer for this? Or is it theoretical?

> @@ -8693,6 +8700,9 @@ static int rtl8152_system_resume(struct r8152 *tp)
>  		usb_submit_urb(tp->intr_urb, GFP_NOIO);
>  	}
>  
> +	clear_bit(RTL8152_SYSTEM_SUSPEND, &tp->flags);
> +	smp_mb__after_atomic();
> +
>  	return 0;
>  }
>  
> @@ -8758,6 +8768,9 @@ static int rtl8152_system_suspend(struct r8152 *tp)
>  {
>  	struct net_device *netdev = tp->netdev;
>  
> +	set_bit(RTL8152_SYSTEM_SUSPEND, &tp->flags);
> +	smp_mb__after_atomic();
> +
>  	netif_device_detach(netdev);
>  
>  	if (netif_running(netdev) && test_bit(WORK_ENABLE, &tp->flags)) {

It seems odd to me that every driver needs to track if it is in
suspend/resume or not. Doesn't the struct device tell you? Is there no
global state somewhere?

       Andrew