Re: [PATCH v8 3/4] mm/madvise: introduce process_madvise() syscall: an external memory hinting API

[Christoph Hellwig]

On Fri, Aug 28, 2020 at 07:40:08PM +0200, Arnd Bergmann wrote:
> Every syscall that passes an iovec seems to do this. If we make import_iovec()
> handle both cases directly, this syscall and a number of others can
> be simplified, and you avoid the x32 entry point I mentioned above

FYI, I do have a series that does this (even tested) and kills tons of
compat syscalls by that.  But by doing that I found the problem that
compat syscalls issued by io_uring don't trigger in_compat_syscall().
I need to go back to fixing the io_uring vs in_compat_syscall() issue
(probably for 5.9) and then submit the whole thing.