[dpdk-stable] [PATCH][v4.9.y] Fixes: 3c226c637b69 ("mm: numa: avoid waiting on freed migrated pages")

[dpdk-stable] [PATCH][v4.9.y] Fixes: 3c226c637b69 ("mm: numa: avoid waiting on freed migrated pages")

[Chas Williams]

From: Chas Williams <chas3@att.com>

Commit 3c226c637b69 ("mm: numa: avoid waiting on freed migrated pages")
was an incomplete backport of the upstream commit.  It is necessary to
always reset page_nid before attempting any early exit.
---
 mm/huge_memory.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 9efe88ef9702..e4c6c3edaf6a 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1259,12 +1259,12 @@ int do_huge_pmd_numa_page(struct fault_env *fe, pmd_t pmd)
 
 	/* Migration could have started since the pmd_trans_migrating check */
 	if (!page_locked) {
+		page_nid = -1;
 		if (!get_page_unless_zero(page))
 			goto out_unlock;
 		spin_unlock(fe->ptl);
 		wait_on_page_locked(page);
 		put_page(page);
-		page_nid = -1;
 		goto out;
 	}
 
-- 
2.14.4

Re: [dpdk-stable] [PATCH][v4.9.y] Fixes: 3c226c637b69 ("mm: numa: avoid waiting on freed migrated pages")

[Yongseok Koh]

> On Sep 4, 2018, at 5:51 PM, Chas Williams <3chas3@gmail.com> wrote:
> 
> From: Chas Williams <chas3@att.com>
> 
> Commit 3c226c637b69 ("mm: numa: avoid waiting on freed migrated pages")
> was an incomplete backport of the upstream commit.  It is necessary to
> always reset page_nid before attempting any early exit.
> ---
> mm/huge_memory.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 9efe88ef9702..e4c6c3edaf6a 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c

Looks like a kernel patch has been sent to DPDK community. ;-)

Thanks,
Yongseok

> @@ -1259,12 +1259,12 @@ int do_huge_pmd_numa_page(struct fault_env *fe, pmd_t pmd)
> 
> 	/* Migration could have started since the pmd_trans_migrating check */
> 	if (!page_locked) {
> +		page_nid = -1;
> 		if (!get_page_unless_zero(page))
> 			goto out_unlock;
> 		spin_unlock(fe->ptl);
> 		wait_on_page_locked(page);
> 		put_page(page);
> -		page_nid = -1;
> 		goto out;
> 	}
> 
> -- 
> 2.14.4
> 

Re: [dpdk-stable] [PATCH][v4.9.y] Fixes: 3c226c637b69 ("mm: numa: avoid waiting on freed migrated pages")

[Chas Williams]

On Wed, Sep 5, 2018 at 2:34 AM Yongseok Koh <yskoh@mellanox.com> wrote:

>
> > On Sep 4, 2018, at 5:51 PM, Chas Williams <3chas3@gmail.com> wrote:
> >
> > From: Chas Williams <chas3@att.com>
> >
> > Commit 3c226c637b69 ("mm: numa: avoid waiting on freed migrated pages")
> > was an incomplete backport of the upstream commit.  It is necessary to
> > always reset page_nid before attempting any early exit.
> > ---
> > mm/huge_memory.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> > index 9efe88ef9702..e4c6c3edaf6a 100644
> > --- a/mm/huge_memory.c
> > +++ b/mm/huge_memory.c
>
> Looks like a kernel patch has been sent to DPDK community. ;-)
>

Well they both start stable... :)  Thanks for the heads up!

>
> Thanks,
> Yongseok
>
> > @@ -1259,12 +1259,12 @@ int do_huge_pmd_numa_page(struct fault_env *fe,
> pmd_t pmd)
> >
> >       /* Migration could have started since the pmd_trans_migrating
> check */
> >       if (!page_locked) {
> > +             page_nid = -1;
> >               if (!get_page_unless_zero(page))
> >                       goto out_unlock;
> >               spin_unlock(fe->ptl);
> >               wait_on_page_locked(page);
> >               put_page(page);
> > -             page_nid = -1;
> >               goto out;
> >       }
> >
> > --
> > 2.14.4
> >
>
>