Re: [RFC PATCH] usb: host: xhci: allow __GFP_FS in dma allocation

[Oliver Neukum]

On Di, 2019-05-21 at 10:00 -0400, Alan Stern wrote:
> 
> Changing configurations amounts to much the same as disconnecting,
> because both operations destroy all the existing interfaces.
> 
> Disconnect can arise in two different ways.
> 
>         Physical hot-unplug: All I/O operations will fail.
> 
>         Rmmod or unbind: I/O operations will succeed.
> 
> The second case is probably okay.  The first we can do nothing about.  
> However, in either case we do need to make sure that memory allocations
> do not require any writebacks.  This suggests that we need to call
> memalloc_noio_save() from within usb_unbind_interface().

I agree with the problem, but I fail to see why this issue would be
specific to USB. Shouldn't this be done in the device core layer?

	Regards
		Oliver