Re: [PATCH] ext4/xfs: add page refcount helper

[Ralph Campbell]

On 10/7/20 1:25 AM, Jan Kara wrote:
> On Tue 06-10-20 16:09:30, Ralph Campbell wrote:
> > There are several places where ZONE_DEVICE struct pages assume a reference
> > count == 1 means the page is idle and free. Instead of open coding this,
> > add a helper function to hide this detail.
> >
> > Signed-off-by: Ralph Campbell <rcampbell@xxxxxxxxxx>
> > Reviewed-by: Christoph Hellwig <hch@xxxxxx>
>
> Looks as sane direction but if we are going to abstract checks when
> ZONE_DEVICE page is idle, we should also update e.g.
> mm/swap.c:put_devmap_managed_page() or
> mm/gup.c:__unpin_devmap_managed_user_page() (there may be more places like
> this but I found at least these two...). Maybe Dan has more thoughts about
> this.
>
> 								Honza

I think this is a good point but I would like to make that a follow on
patch rather than add to this one.