Re: [PATCH 1/2] mm: introduce put_user_page*(), placeholder versions

[Matthew Wilcox]

On Wed, Dec 12, 2018 at 04:53:49PM -0500, Jerome Glisse wrote:
> The mmu notifier i put forward is the emergency revoke ie last
> resort after driver have done everything it could to inform user-
> space and release the pages. So doing thing brutaly in it like
> reprogramming driver page table (which AFAIK is something you
> can do on any hardware wether the hardware will like it or not
> is a different question).

You can't do it to an NVMe device.  You submit the DMA addresses in
the command, and the device reads the command at submission time.
There's no way to change the DMA addresses for an in-flight command.