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.
Cc: Jérôme Glisse <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: John Hubbard <[email protected]>
Signed-off-by: Ira Weiny <[email protected]>
---
mm/swap.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/mm/swap.c b/mm/swap.c
index 3a75722e68a9..d1e8122568d0 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -739,15 +739,14 @@ 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;
+ if (put_devmap_managed_page(page))
+ continue;
}
page = compound_head(page);
--
2.20.1
On 5/23/19 3:37 PM, [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.
>
> Cc: Jérôme Glisse <[email protected]>
> Cc: Dan Williams <[email protected]>
> Cc: Michal Hocko <[email protected]>
> Cc: John Hubbard <[email protected]>
> Signed-off-by: Ira Weiny <[email protected]>
> ---
> mm/swap.c | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/mm/swap.c b/mm/swap.c
> index 3a75722e68a9..d1e8122568d0 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -739,15 +739,14 @@ 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;
> + if (put_devmap_managed_page(page))
> + continue;
> }
>
> page = compound_head(page);
>
Reviewed-by: John Hubbard <[email protected]>
thanks,
--
John Hubbard
NVIDIA
On Thu, May 23, 2019 at 3:37 PM <[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.
>
> Cc: Jérôme Glisse <[email protected]>
> Cc: Dan Williams <[email protected]>
> Cc: Michal Hocko <[email protected]>
> Cc: John Hubbard <[email protected]>
> Signed-off-by: Ira Weiny <[email protected]>
> ---
> mm/swap.c | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/mm/swap.c b/mm/swap.c
> index 3a75722e68a9..d1e8122568d0 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -739,15 +739,14 @@ 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;
> + if (put_devmap_managed_page(page))
This "shouldn't" fail, and if it does the code that follows might get
confused by a ZONE_DEVICE page. If anything I would make this a
WARN_ON_ONCE(!put_devmap_managed_page(page)), but always continue
unconditionally.
Other than that you can add:
Reviewed-by: Dan Williams <[email protected]>
On Thu, May 23, 2019 at 08:58:12PM -0700, Dan Williams wrote:
> On Thu, May 23, 2019 at 3:37 PM <[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.
> >
> > Cc: J?r?me Glisse <[email protected]>
> > Cc: Dan Williams <[email protected]>
> > Cc: Michal Hocko <[email protected]>
> > Cc: John Hubbard <[email protected]>
> > Signed-off-by: Ira Weiny <[email protected]>
> > ---
> > mm/swap.c | 7 +++----
> > 1 file changed, 3 insertions(+), 4 deletions(-)
> >
> > diff --git a/mm/swap.c b/mm/swap.c
> > index 3a75722e68a9..d1e8122568d0 100644
> > --- a/mm/swap.c
> > +++ b/mm/swap.c
> > @@ -739,15 +739,14 @@ 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;
> > + if (put_devmap_managed_page(page))
>
> This "shouldn't" fail, and if it does the code that follows might get
I agree it shouldn't based on the check. However...
> confused by a ZONE_DEVICE page. If anything I would make this a
> WARN_ON_ONCE(!put_devmap_managed_page(page)), but always continue
> unconditionally.
I was trying to follow the pattern from put_page() Where if fails it indicated
it was not a devmap page and so "regular" processing should continue.
Since I'm unsure I'll just ask what does this check do?
if (!static_branch_unlikely(&devmap_managed_key))
return false;
... In put_devmap_managed_page()?
>
> Other than that you can add:
>
> Reviewed-by: Dan Williams <[email protected]>
Thanks v2 to follow.
Ira
On Fri, May 24, 2019 at 8:35 AM Ira Weiny <[email protected]> wrote:
>
> On Thu, May 23, 2019 at 08:58:12PM -0700, Dan Williams wrote:
> > On Thu, May 23, 2019 at 3:37 PM <[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.
> > >
> > > Cc: Jérôme Glisse <[email protected]>
> > > Cc: Dan Williams <[email protected]>
> > > Cc: Michal Hocko <[email protected]>
> > > Cc: John Hubbard <[email protected]>
> > > Signed-off-by: Ira Weiny <[email protected]>
> > > ---
> > > mm/swap.c | 7 +++----
> > > 1 file changed, 3 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/mm/swap.c b/mm/swap.c
> > > index 3a75722e68a9..d1e8122568d0 100644
> > > --- a/mm/swap.c
> > > +++ b/mm/swap.c
> > > @@ -739,15 +739,14 @@ 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;
> > > + if (put_devmap_managed_page(page))
> >
> > This "shouldn't" fail, and if it does the code that follows might get
>
> I agree it shouldn't based on the check. However...
>
> > confused by a ZONE_DEVICE page. If anything I would make this a
> > WARN_ON_ONCE(!put_devmap_managed_page(page)), but always continue
> > unconditionally.
>
> I was trying to follow the pattern from put_page() Where if fails it indicated
> it was not a devmap page and so "regular" processing should continue.
In this case that regular continuation already happened by not taking
the if (is_zone_device_page(page)) branch
>
> Since I'm unsure I'll just ask what does this check do?
>
> if (!static_branch_unlikely(&devmap_managed_key))
> return false;
That attempts to skip the overhead imposed by device-pages, i.e.
->page_free() callback and other extras, if there are no device-page
producers in the system. I.e. use the old simple put_page() path when
there is no hmm or pmem.
On Thu, May 23, 2019 at 8:58 PM Dan Williams <[email protected]> wrote:
>
> On Thu, May 23, 2019 at 3:37 PM <[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.
> >
> > Cc: Jérôme Glisse <[email protected]>
> > Cc: Dan Williams <[email protected]>
> > Cc: Michal Hocko <[email protected]>
> > Cc: John Hubbard <[email protected]>
> > Signed-off-by: Ira Weiny <[email protected]>
> > ---
> > mm/swap.c | 7 +++----
> > 1 file changed, 3 insertions(+), 4 deletions(-)
> >
> > diff --git a/mm/swap.c b/mm/swap.c
> > index 3a75722e68a9..d1e8122568d0 100644
> > --- a/mm/swap.c
> > +++ b/mm/swap.c
> > @@ -739,15 +739,14 @@ 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;
> > + if (put_devmap_managed_page(page))
>
> This "shouldn't" fail, and if it does the code that follows might get
> confused by a ZONE_DEVICE page. If anything I would make this a
> WARN_ON_ONCE(!put_devmap_managed_page(page)), but always continue
> unconditionally.
As discussed offline, I'm wrong here. It needs to fall through to
put_page_testzero() for the device-dax case, but perhaps a comment for
the next time I forget that subtlety.