On Fri 24-05-19 10:36:56, [email protected] wrote: > From: Ira Weiny <[email protected]> > > Device pages can be more than type MEMORY_DEVICE_PUBLIC. > > Handle all device pages within release_pages() > > This was found via code inspection while determining if release_pages() > and the new put_user_pages() could be interchangeable.
Please expand more about who is such a user and why does it use release_pages rather than put_*page API. The above changelog doesn't really help understanding what is the actual problem. I also do not understand the fix and a failure mode from release_pages is just scary. It is basically impossible to handle the error case. So what is going on here? > Cc: Jérôme Glisse <[email protected]> > Cc: Michal Hocko <[email protected]> > Reviewed-by: Dan Williams <[email protected]> > Reviewed-by: John Hubbard <[email protected]> > Signed-off-by: Ira Weiny <[email protected]> > > --- > Changes from V1: > Add comment clarifying that put_devmap_managed_page() can still > fail. > Add Reviewed-by tags. > > mm/swap.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/mm/swap.c b/mm/swap.c > index 9d0432baddb0..f03b7b4bfb4f 100644 > --- a/mm/swap.c > +++ b/mm/swap.c > @@ -740,15 +740,18 @@ void release_pages(struct page **pages, int nr) > if (is_huge_zero_page(page)) > continue; > > - /* Device public page can not be huge page */ > - if (is_device_public_page(page)) { > + if (is_zone_device_page(page)) { > if (locked_pgdat) { > spin_unlock_irqrestore(&locked_pgdat->lru_lock, > flags); > locked_pgdat = NULL; > } > - put_devmap_managed_page(page); > - continue; > + /* > + * zone-device-pages can still fail here and will > + * therefore need put_page_testzero() > + */ > + if (put_devmap_managed_page(page)) > + continue; > } > > page = compound_head(page); > -- > 2.20.1 > -- Michal Hocko SUSE Labs
