Re: [PATCH v5 08/14] mm/gup: do not allow zero page for pinned pages

[Jason Gunthorpe]

On Mon, Jan 18, 2021 at 11:39:14PM -0500, Pavel Tatashin wrote:
> Zero page should not be used for long term pinned pages. Once pages
> are pinned their physical addresses cannot changed until they are unpinned.
> 
> Guarantee to always return real pages when they are pinned by adding
> FOLL_WRITE.
> 
> Signed-off-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
> ---
>  mm/gup.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)

No, this will definitely break things

Why does the zero page have to be movable?

Jason