[PATCH RFC] mm: Add f_ops->populate()

[Matthew Wilcox]

On Sun, Mar 06, 2022 at 04:15:33AM +0200, Jarkko Sakkinen wrote:
> Sometimes you might want to use MAP_POPULATE to ask a device driver to
> initialize the device memory in some specific manner. SGX driver can use
> this to request more memory by issuing ENCLS[EAUG] x86 opcode for each
> page in the address range.
> 
> Add f_ops->populate() with the same parameters as f_ops->mmap() and make
> it conditionally called inside call_mmap(). Update call sites
> accodingly.

Your device driver has a ->mmap operation.  Why does it need another
one?  More explanation required here.