Re: [PATCH 02/11] mm: call import_iovec() instead of rw_copy_check_uvector() in process_vm_rw()

[Matthew Wilcox]

On Mon, Sep 21, 2020 at 04:34:25PM +0200, Christoph Hellwig wrote:
>  {
> -     WARN_ON(direction & ~(READ | WRITE));
> +     WARN_ON(direction & ~(READ | WRITE | CHECK_IOVEC_ONLY));

This is now a no-op because:

include/linux/fs.h:#define CHECK_IOVEC_ONLY -1

I'd suggest we renumber it to 2?

(READ is 0, WRITE is 1.  This WARN_ON should probably be
        WARN_ON(direction > CHECK_IOVEC_ONLY)