On Wed, Oct 7, 2020 at 1:25 AM Jan Kara <jack@xxxxxxx> 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. Yes, but I think that cleanup comes once the idle page count is unified to be 0 across typical and ZONE_DEVICE pages. Then free_devmap_managed_page() can be moved internal to __put_page(). For this patch it's just hiding the "idle == 1" assumption from dax-filesystems.
