Re: [PATCH 2/2] exec: open code copy_string_kernel

[Al Viro]

On Fri, May 01, 2020 at 12:41:05PM +0200, Christoph Hellwig wrote:
> Currently copy_string_kernel is just a wrapper around copy_strings that
> simplifies the calling conventions and uses set_fs to allow passing a
> kernel pointer.  But due to the fact the we only need to handle a single
> kernel argument pointer, the logic can be sigificantly simplified while
> getting rid of the set_fs.

I can live with that...  BTW, why do we bother with flush_cache_page() (by
way of get_arg_page()) here and in copy_strings()?  How could *anything*
have accessed that page by its address in new mm - what are we trying to
flush here?