Re: [PATCH v8 10/10] mm: Renumber FOLL_PIN and FOLL_GET down

[Christoph Hellwig]

On Mon, Jan 23, 2023 at 05:30:07PM +0000, David Howells wrote:
> Renumber FOLL_PIN and FOLL_GET down to bit 0 and 1 respectively so that
> they are coincidentally the same as BIO_PAGE_PINNED and BIO_PAGE_REFFED and
> also so that they can be stored in the bottom two bits of a page pointer
> (something I'm looking at for zerocopy socket fragments).
> 
> (Note that BIO_PAGE_REFFED should probably be got rid of at some point,
> hence why FOLL_PIN is at 0.)
> 
> Also renumber down the other FOLL_* flags to close the gaps.

Taking the risk of having a long bikeshed:  I much prefer (1U << bitnr)
style definition that make it obvious where there are holes, but
otherwise:

Reviewed-by: Christoph Hellwig <hch@xxxxxx>