Re: [PATCH 2/4] mm/gup: explicitly define and check internal GUP flags, disallow FOLL_TOUCH

[Jason Gunthorpe]

On Sun, Oct 01, 2023 at 05:00:03PM +0100, Lorenzo Stoakes wrote:
> Rather than open-coding a list of internal GUP flags in
> is_valid_gup_args(), define which ones are internal.
> 
> In addition, we were not explicitly checking to see if the user passed in
> FOLL_TOUCH somehow, this patch fixes that.
> 
> Signed-off-by: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
> ---
>  mm/gup.c      | 5 ++---
>  mm/internal.h | 3 +++
>  2 files changed, 5 insertions(+), 3 deletions(-)

Does gup_test still work? It uses FOLL_TOUCH?

Hmm. I guess it was broken for a while anyhow:

/* Just the flags we need, copied from mm.h: */
#define FOLL_WRITE	0x01	/* check pte is writable */
#define FOLL_TOUCH	0x02	/* mark page accessed */

Aside from that this seems OK

Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>

Jason