diff mbox series

[1/3] mm/gup: Use huge_ptep_get() in gup_hugepte()

Message ID ffc3714334c3bfaca6f13788ad039e8759ae413f.1592225558.git.christophe.leroy@csgroup.eu (mailing list archive)
State New, archived
Headers show
Series Fix build failure with v5.8-rc1 | expand

Commit Message

Christophe Leroy June 15, 2020, 12:57 p.m. UTC 
gup_hugepte() reads hugepage table entries, it can't read
them directly, huge_ptep_get() must be used.

Fixes: 2ab3a0a02905 ("READ_ONCE: Enforce atomicity for {READ,WRITE}_ONCE() memory accesses")
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 mm/gup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Michael Ellerman June 17, 2020, 2:14 p.m. UTC | #1 
Christophe Leroy <christophe.leroy@csgroup.eu> writes:
> gup_hugepte() reads hugepage table entries, it can't read
> them directly, huge_ptep_get() must be used.
>
> Fixes: 2ab3a0a02905 ("READ_ONCE: Enforce atomicity for {READ,WRITE}_ONCE() memory accesses")

I see that commit in older versions of linux-next but not in mainline.

In mainline it seems to be: 9e343b467c70 ("READ_ONCE: Enforce atomicity for {READ,WRITE}_ONCE() memory accesses")

I guess it got rebased somewhere along the way.

I fixed it up when applying, and the other two as well.

cheers

> Cc: Will Deacon <will@kernel.org>
> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> ---
>  mm/gup.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/gup.c b/mm/gup.c
> index de9e36262ccb..761df4944ef5 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -2425,7 +2425,7 @@ static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
>  	if (pte_end < end)
>  		end = pte_end;
>  
> -	pte = READ_ONCE(*ptep);
> +	pte = huge_ptep_get(ptep);
>  
>  	if (!pte_access_permitted(pte, flags & FOLL_WRITE))
>  		return 0;
> -- 
> 2.25.0
diff mbox series

Patch

diff --git a/mm/gup.c b/mm/gup.c
index de9e36262ccb..761df4944ef5 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2425,7 +2425,7 @@  static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
 	if (pte_end < end)
 		end = pte_end;
 
-	pte = READ_ONCE(*ptep);
+	pte = huge_ptep_get(ptep);
 
 	if (!pte_access_permitted(pte, flags & FOLL_WRITE))
 		return 0;