This patchset has a fixup for gup/mm, and provides the necessary arch
hooks to enable protected virtualization.
Claudio Imbrenda (2):
mm/gup: fixup for 9947ea2c1e608e32 "mm/gup: track FOLL_PIN pages"
mm/gup/writeback: add callbacks for inaccessible pages
include/linux/gfp.h | 6 ++++++
mm/gup.c | 24 ++++++++++++++++++++----
mm/page-writeback.c | 5 +++++
3 files changed, 31 insertions(+), 4 deletions(-)
--
2.24.1
In case pin fails, we need to unpin, a simple put_page will not be enough
Signed-off-by: Claudio Imbrenda <[email protected]>
---
mm/gup.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/mm/gup.c b/mm/gup.c
index f589299b0d4a..0b9a806898f3 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2134,7 +2134,10 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
goto pte_unmap;
if (unlikely(pte_val(pte) != pte_val(*ptep))) {
- put_page(head);
+ if (flags & FOLL_GET)
+ put_page(head);
+ else if (flags & FOLL_PIN)
+ unpin_user_page(head);
goto pte_unmap;
}
--
2.24.1
On 2/28/20 7:43 AM, Claudio Imbrenda wrote:
> In case pin fails, we need to unpin, a simple put_page will not be enough
>
> Signed-off-by: Claudio Imbrenda <[email protected]>
> ---
> mm/gup.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/mm/gup.c b/mm/gup.c
> index f589299b0d4a..0b9a806898f3 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -2134,7 +2134,10 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
> goto pte_unmap;
>
> if (unlikely(pte_val(pte) != pte_val(*ptep))) {
> - put_page(head);
> + if (flags & FOLL_GET)
> + put_page(head);
> + else if (flags & FOLL_PIN)
> + unpin_user_page(head);
Hi Claudio,
Instead, I think that should actually be:
put_compound_head(page, 1, flags);
which does a bit more (bug checks and /proc/vmstat instrumentation) than your diff,
but has the same basic idea: call the right "put" function.
...oh, actually, I see you have the commit hash in the subject line. Instead, it should
be in the commit description. Let's maybe change the subject line to approx:
mm/gup: Fix a missing put_compound_head() call in gup_pte_range()
And the write up...how about something like this, if you like it:
try_grab_compound_head() must be undone via put_compound_head(), not put_page().
This was missed in the original implementation of the gup/dma tracking patch, so
fix it now.
Fixes: 0ea2781c3de4 ("mm/gup: track FOLL_PIN pages")
(Aside: I'm using the linux-next commit hash. How does one get the correct hash before
it goes to mainline? I guess maintainer scripts fix all those up?)
It's also good to Cc some reviewers in case I'm overlooking something, so I'm adding
Jan and Kirill.
thanks,
--
John Hubbard
NVIDIA
> goto pte_unmap;
> }
>
>
On Fri, 28 Feb 2020 15:08:35 -0800
John Hubbard <[email protected]> wrote:
> On 2/28/20 7:43 AM, Claudio Imbrenda wrote:
> > In case pin fails, we need to unpin, a simple put_page will not be
> > enough
> >
> > Signed-off-by: Claudio Imbrenda <[email protected]>
> > ---
> > mm/gup.c | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/mm/gup.c b/mm/gup.c
> > index f589299b0d4a..0b9a806898f3 100644
> > --- a/mm/gup.c
> > +++ b/mm/gup.c
> > @@ -2134,7 +2134,10 @@ static int gup_pte_range(pmd_t pmd, unsigned
> > long addr, unsigned long end, goto pte_unmap;
> >
> > if (unlikely(pte_val(pte) != pte_val(*ptep))) {
> > - put_page(head);
> > + if (flags & FOLL_GET)
> > + put_page(head);
> > + else if (flags & FOLL_PIN)
> > + unpin_user_page(head);
>
> Hi Claudio,
>
> Instead, I think that should actually be:
>
> put_compound_head(page, 1, flags);
that makes sense, yes :)
I'll fix it in the next iteration
>
> which does a bit more (bug checks and /proc/vmstat instrumentation)
> than your diff, but has the same basic idea: call the right "put"
> function.
>
> ...oh, actually, I see you have the commit hash in the subject line.
> Instead, it should be in the commit description. Let's maybe change
> the subject line to approx:
>
> mm/gup: Fix a missing put_compound_head() call in gup_pte_range()
>
> And the write up...how about something like this, if you like it:
>
>
> try_grab_compound_head() must be undone via put_compound_head(), not
> put_page(). This was missed in the original implementation of the
> gup/dma tracking patch, so fix it now.
>
> Fixes: 0ea2781c3de4 ("mm/gup: track FOLL_PIN pages")
>
>
>
> (Aside: I'm using the linux-next commit hash. How does one get the
> correct hash before it goes to mainline? I guess maintainer scripts
> fix all those up?)
my idea was that my patch should be used as fix-up, so the actual
content of the commit message is not relevant
> It's also good to Cc some reviewers in case I'm overlooking
> something, so I'm adding Jan and Kirill.
>
> thanks,
On 2/29/20 2:51 AM, Claudio Imbrenda wrote:
> my idea was that my patch should be used as fix-up, so the actual
> content of the commit message is not relevant
>
aha, OK. Yes, a fixup would be nice.
thanks,
--
John Hubbard
NVIDIA
On Fri 28-02-20 15:08:35, John Hubbard wrote:
[...]
> (Aside: I'm using the linux-next commit hash. How does one get the correct hash before
> it goes to mainline? I guess maintainer scripts fix all those up?)
There is no such maging going on AFAIK. Please just do not use sha1 from
linux-next unless it is really clear that those are not going to change.
So essentially everything from mmotm is out of question.
--
Michal Hocko
SUSE Labs