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

[Chih Kai Hsu <hsu.chih.kai@realtek.com>]

On Mon, Aug 11, 2026 at 02:03 AM +0800, Andrew Lunn wrote:
> 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?
> 

It is 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?

I found https://elixir.bootlin.com/linux/v7.2-rc6/source/drivers/base/power/main.c#L2343 
in the Linux source code.

pm_restrict_gfp_mask() is called before dpm_suspend(state). It removes __GFP_IO
and __GFP_FS from the global gfp_t gfp_allowed_mask. Therefore, I think the driver
can use GFP_KERNEL safely. Is this correct? Could you please provide any advice?


> 
>        Andrew

Best,
Chih-Kai