* [PATCH] arm64: Don't report clear pmds and puds as huge
@ 2015-07-01 12:08 ` Christoffer Dall
0 siblings, 0 replies; 14+ messages in thread
From: Christoffer Dall @ 2015-07-01 12:08 UTC (permalink / raw)
To: linux-arm-kernel
The current pmd_huge() and pud_huge() functions simply check if the table
bit is not set and reports the entries as huge in that case. This is
counter-intuitive as a clear pmd/pud cannot also be a huge pmd/pud, and
it is inconsistent with at least arm and x86.
To prevent others from making the same mistake as me in looking at code
that calls these functions and to fix an issue with KVM on arm64 that
causes memory corruption due to incorrect page reference counting
resulting from this mistake, let's change the behavior.
Cc: stable at vger.kernel.org
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
arch/arm64/mm/hugetlbpage.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index 2de9d2e..0eeb4f09 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -40,13 +40,13 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
int pmd_huge(pmd_t pmd)
{
- return !(pmd_val(pmd) & PMD_TABLE_BIT);
+ return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
}
int pud_huge(pud_t pud)
{
#ifndef __PAGETABLE_PMD_FOLDED
- return !(pud_val(pud) & PUD_TABLE_BIT);
+ return pud_val(pud) && !(pud_val(pud) & PUD_TABLE_BIT);
#else
return 0;
#endif
--
2.1.2.330.g565301e.dirty
^ permalink raw reply related [flat|nested] 14+ messages in thread* Re: [PATCH] arm64: Don't report clear pmds and puds as huge
2015-07-01 12:08 ` Christoffer Dall
@ 2015-07-01 12:24 ` Steve Capper
-1 siblings, 0 replies; 14+ messages in thread
From: Steve Capper @ 2015-07-01 12:24 UTC (permalink / raw)
To: Christoffer Dall
Cc: linux-arm-kernel@lists.infradead.org, Alexander Graf,
Marc Zyngier, Catalin Marinas, kvmarm, Dirk Müller, stable
On 1 July 2015 at 13:08, Christoffer Dall <christoffer.dall@linaro.org> wrote:
> The current pmd_huge() and pud_huge() functions simply check if the table
> bit is not set and reports the entries as huge in that case. This is
> counter-intuitive as a clear pmd/pud cannot also be a huge pmd/pud, and
> it is inconsistent with at least arm and x86.
>
> To prevent others from making the same mistake as me in looking at code
> that calls these functions and to fix an issue with KVM on arm64 that
> causes memory corruption due to incorrect page reference counting
> resulting from this mistake, let's change the behavior.
>
> Cc: stable@vger.kernel.org
Thanks Christoffer.
It may be worth adding:
Fixes: 084bd29810a5 ("ARM64: mm: HugeTLB support.")
And, please feel free to add:
Reviewed-by: Steve Capper <steve.capper@linaro.org>
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
> ---
> arch/arm64/mm/hugetlbpage.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index 2de9d2e..0eeb4f09 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -40,13 +40,13 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
>
> int pmd_huge(pmd_t pmd)
> {
> - return !(pmd_val(pmd) & PMD_TABLE_BIT);
> + return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
> }
>
> int pud_huge(pud_t pud)
> {
> #ifndef __PAGETABLE_PMD_FOLDED
> - return !(pud_val(pud) & PUD_TABLE_BIT);
> + return pud_val(pud) && !(pud_val(pud) & PUD_TABLE_BIT);
> #else
> return 0;
> #endif
> --
> 2.1.2.330.g565301e.dirty
>
^ permalink raw reply [flat|nested] 14+ messages in thread* [PATCH] arm64: Don't report clear pmds and puds as huge
@ 2015-07-01 12:24 ` Steve Capper
0 siblings, 0 replies; 14+ messages in thread
From: Steve Capper @ 2015-07-01 12:24 UTC (permalink / raw)
To: linux-arm-kernel
On 1 July 2015 at 13:08, Christoffer Dall <christoffer.dall@linaro.org> wrote:
> The current pmd_huge() and pud_huge() functions simply check if the table
> bit is not set and reports the entries as huge in that case. This is
> counter-intuitive as a clear pmd/pud cannot also be a huge pmd/pud, and
> it is inconsistent with at least arm and x86.
>
> To prevent others from making the same mistake as me in looking at code
> that calls these functions and to fix an issue with KVM on arm64 that
> causes memory corruption due to incorrect page reference counting
> resulting from this mistake, let's change the behavior.
>
> Cc: stable at vger.kernel.org
Thanks Christoffer.
It may be worth adding:
Fixes: 084bd29810a5 ("ARM64: mm: HugeTLB support.")
And, please feel free to add:
Reviewed-by: Steve Capper <steve.capper@linaro.org>
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
> ---
> arch/arm64/mm/hugetlbpage.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index 2de9d2e..0eeb4f09 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -40,13 +40,13 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
>
> int pmd_huge(pmd_t pmd)
> {
> - return !(pmd_val(pmd) & PMD_TABLE_BIT);
> + return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
> }
>
> int pud_huge(pud_t pud)
> {
> #ifndef __PAGETABLE_PMD_FOLDED
> - return !(pud_val(pud) & PUD_TABLE_BIT);
> + return pud_val(pud) && !(pud_val(pud) & PUD_TABLE_BIT);
> #else
> return 0;
> #endif
> --
> 2.1.2.330.g565301e.dirty
>
^ permalink raw reply [flat|nested] 14+ messages in thread* Re: [PATCH] arm64: Don't report clear pmds and puds as huge
2015-07-01 12:24 ` Steve Capper
@ 2015-07-01 12:59 ` Christoffer Dall
-1 siblings, 0 replies; 14+ messages in thread
From: Christoffer Dall @ 2015-07-01 12:59 UTC (permalink / raw)
To: Steve Capper
Cc: linux-arm-kernel@lists.infradead.org, Alexander Graf,
Marc Zyngier, Catalin Marinas, kvmarm, Dirk Müller, stable
On Wed, Jul 01, 2015 at 01:24:34PM +0100, Steve Capper wrote:
> On 1 July 2015 at 13:08, Christoffer Dall <christoffer.dall@linaro.org> wrote:
> > The current pmd_huge() and pud_huge() functions simply check if the table
> > bit is not set and reports the entries as huge in that case. This is
> > counter-intuitive as a clear pmd/pud cannot also be a huge pmd/pud, and
> > it is inconsistent with at least arm and x86.
> >
> > To prevent others from making the same mistake as me in looking at code
> > that calls these functions and to fix an issue with KVM on arm64 that
> > causes memory corruption due to incorrect page reference counting
> > resulting from this mistake, let's change the behavior.
> >
> > Cc: stable@vger.kernel.org
>
> Thanks Christoffer.
>
> It may be worth adding:
>
> Fixes: 084bd29810a5 ("ARM64: mm: HugeTLB support.")
>
> And, please feel free to add:
>
> Reviewed-by: Steve Capper <steve.capper@linaro.org>
>
Thanks!
-Christoffer
^ permalink raw reply [flat|nested] 14+ messages in thread* [PATCH] arm64: Don't report clear pmds and puds as huge
@ 2015-07-01 12:59 ` Christoffer Dall
0 siblings, 0 replies; 14+ messages in thread
From: Christoffer Dall @ 2015-07-01 12:59 UTC (permalink / raw)
To: linux-arm-kernel
On Wed, Jul 01, 2015 at 01:24:34PM +0100, Steve Capper wrote:
> On 1 July 2015 at 13:08, Christoffer Dall <christoffer.dall@linaro.org> wrote:
> > The current pmd_huge() and pud_huge() functions simply check if the table
> > bit is not set and reports the entries as huge in that case. This is
> > counter-intuitive as a clear pmd/pud cannot also be a huge pmd/pud, and
> > it is inconsistent with at least arm and x86.
> >
> > To prevent others from making the same mistake as me in looking at code
> > that calls these functions and to fix an issue with KVM on arm64 that
> > causes memory corruption due to incorrect page reference counting
> > resulting from this mistake, let's change the behavior.
> >
> > Cc: stable at vger.kernel.org
>
> Thanks Christoffer.
>
> It may be worth adding:
>
> Fixes: 084bd29810a5 ("ARM64: mm: HugeTLB support.")
>
> And, please feel free to add:
>
> Reviewed-by: Steve Capper <steve.capper@linaro.org>
>
Thanks!
-Christoffer
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH] arm64: Don't report clear pmds and puds as huge
2015-07-01 12:08 ` Christoffer Dall
@ 2015-07-01 13:07 ` Marc Zyngier
-1 siblings, 0 replies; 14+ messages in thread
From: Marc Zyngier @ 2015-07-01 13:07 UTC (permalink / raw)
To: Christoffer Dall, linux-arm-kernel@lists.infradead.org
Cc: Steve Capper, agraf@suse.de, Catalin Marinas,
kvmarm@lists.cs.columbia.edu, dirk@dmllr.de,
stable@vger.kernel.org
On 01/07/15 13:08, Christoffer Dall wrote:
> The current pmd_huge() and pud_huge() functions simply check if the table
> bit is not set and reports the entries as huge in that case. This is
> counter-intuitive as a clear pmd/pud cannot also be a huge pmd/pud, and
> it is inconsistent with at least arm and x86.
>
> To prevent others from making the same mistake as me in looking at code
> that calls these functions and to fix an issue with KVM on arm64 that
> causes memory corruption due to incorrect page reference counting
> resulting from this mistake, let's change the behavior.
>
> Cc: stable@vger.kernel.org
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
FWIW:
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
M.
--
Jazz is not dead. It just smells funny...
^ permalink raw reply [flat|nested] 14+ messages in thread
* [PATCH] arm64: Don't report clear pmds and puds as huge
@ 2015-07-01 13:07 ` Marc Zyngier
0 siblings, 0 replies; 14+ messages in thread
From: Marc Zyngier @ 2015-07-01 13:07 UTC (permalink / raw)
To: linux-arm-kernel
On 01/07/15 13:08, Christoffer Dall wrote:
> The current pmd_huge() and pud_huge() functions simply check if the table
> bit is not set and reports the entries as huge in that case. This is
> counter-intuitive as a clear pmd/pud cannot also be a huge pmd/pud, and
> it is inconsistent with at least arm and x86.
>
> To prevent others from making the same mistake as me in looking at code
> that calls these functions and to fix an issue with KVM on arm64 that
> causes memory corruption due to incorrect page reference counting
> resulting from this mistake, let's change the behavior.
>
> Cc: stable at vger.kernel.org
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
FWIW:
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
M.
--
Jazz is not dead. It just smells funny...
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH] arm64: Don't report clear pmds and puds as huge
2015-07-01 12:08 ` Christoffer Dall
@ 2015-07-01 13:18 ` Catalin Marinas
-1 siblings, 0 replies; 14+ messages in thread
From: Catalin Marinas @ 2015-07-01 13:18 UTC (permalink / raw)
To: Christoffer Dall
Cc: linux-arm-kernel, Steve Capper, dirk, Marc Zyngier,
Alexander Graf, stable, kvmarm
On Wed, Jul 01, 2015 at 02:08:31PM +0200, Christoffer Dall wrote:
> The current pmd_huge() and pud_huge() functions simply check if the table
> bit is not set and reports the entries as huge in that case. This is
> counter-intuitive as a clear pmd/pud cannot also be a huge pmd/pud, and
> it is inconsistent with at least arm and x86.
>
> To prevent others from making the same mistake as me in looking at code
> that calls these functions and to fix an issue with KVM on arm64 that
> causes memory corruption due to incorrect page reference counting
> resulting from this mistake, let's change the behavior.
>
> Cc: stable@vger.kernel.org
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
> ---
> arch/arm64/mm/hugetlbpage.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index 2de9d2e..0eeb4f09 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -40,13 +40,13 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
>
> int pmd_huge(pmd_t pmd)
> {
> - return !(pmd_val(pmd) & PMD_TABLE_BIT);
> + return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
> }
>
> int pud_huge(pud_t pud)
> {
> #ifndef __PAGETABLE_PMD_FOLDED
> - return !(pud_val(pud) & PUD_TABLE_BIT);
> + return pud_val(pud) && !(pud_val(pud) & PUD_TABLE_BIT);
> #else
> return 0;
> #endif
Thanks for the patch, I'll add the acks/reviews and Fixes: tags.
(and I think I'll change pmd_val to pmd_present, same for pud; no
functional difference)
--
Catalin
^ permalink raw reply [flat|nested] 14+ messages in thread* [PATCH] arm64: Don't report clear pmds and puds as huge
@ 2015-07-01 13:18 ` Catalin Marinas
0 siblings, 0 replies; 14+ messages in thread
From: Catalin Marinas @ 2015-07-01 13:18 UTC (permalink / raw)
To: linux-arm-kernel
On Wed, Jul 01, 2015 at 02:08:31PM +0200, Christoffer Dall wrote:
> The current pmd_huge() and pud_huge() functions simply check if the table
> bit is not set and reports the entries as huge in that case. This is
> counter-intuitive as a clear pmd/pud cannot also be a huge pmd/pud, and
> it is inconsistent with at least arm and x86.
>
> To prevent others from making the same mistake as me in looking at code
> that calls these functions and to fix an issue with KVM on arm64 that
> causes memory corruption due to incorrect page reference counting
> resulting from this mistake, let's change the behavior.
>
> Cc: stable at vger.kernel.org
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
> ---
> arch/arm64/mm/hugetlbpage.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index 2de9d2e..0eeb4f09 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -40,13 +40,13 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
>
> int pmd_huge(pmd_t pmd)
> {
> - return !(pmd_val(pmd) & PMD_TABLE_BIT);
> + return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
> }
>
> int pud_huge(pud_t pud)
> {
> #ifndef __PAGETABLE_PMD_FOLDED
> - return !(pud_val(pud) & PUD_TABLE_BIT);
> + return pud_val(pud) && !(pud_val(pud) & PUD_TABLE_BIT);
> #else
> return 0;
> #endif
Thanks for the patch, I'll add the acks/reviews and Fixes: tags.
(and I think I'll change pmd_val to pmd_present, same for pud; no
functional difference)
--
Catalin
^ permalink raw reply [flat|nested] 14+ messages in thread* Re: [PATCH] arm64: Don't report clear pmds and puds as huge
2015-07-01 13:18 ` Catalin Marinas
@ 2015-07-01 13:28 ` Catalin Marinas
-1 siblings, 0 replies; 14+ messages in thread
From: Catalin Marinas @ 2015-07-01 13:28 UTC (permalink / raw)
To: Christoffer Dall
Cc: Steve Capper, dirk, Marc Zyngier, Alexander Graf, stable, kvmarm,
linux-arm-kernel
On Wed, Jul 01, 2015 at 02:18:31PM +0100, Catalin Marinas wrote:
> On Wed, Jul 01, 2015 at 02:08:31PM +0200, Christoffer Dall wrote:
> > diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> > index 2de9d2e..0eeb4f09 100644
> > --- a/arch/arm64/mm/hugetlbpage.c
> > +++ b/arch/arm64/mm/hugetlbpage.c
> > @@ -40,13 +40,13 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
> >
> > int pmd_huge(pmd_t pmd)
> > {
> > - return !(pmd_val(pmd) & PMD_TABLE_BIT);
> > + return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
> > }
> >
> > int pud_huge(pud_t pud)
> > {
> > #ifndef __PAGETABLE_PMD_FOLDED
> > - return !(pud_val(pud) & PUD_TABLE_BIT);
> > + return pud_val(pud) && !(pud_val(pud) & PUD_TABLE_BIT);
> > #else
> > return 0;
> > #endif
>
> Thanks for the patch, I'll add the acks/reviews and Fixes: tags.
>
> (and I think I'll change pmd_val to pmd_present, same for pud; no
> functional difference)
A related question - can we ever have PROT_NONE on a huge pmd? I'll
leave this patch with pmd_val for now, it matches pmd_trans_huge().
--
Catalin
^ permalink raw reply [flat|nested] 14+ messages in thread* [PATCH] arm64: Don't report clear pmds and puds as huge
@ 2015-07-01 13:28 ` Catalin Marinas
0 siblings, 0 replies; 14+ messages in thread
From: Catalin Marinas @ 2015-07-01 13:28 UTC (permalink / raw)
To: linux-arm-kernel
On Wed, Jul 01, 2015 at 02:18:31PM +0100, Catalin Marinas wrote:
> On Wed, Jul 01, 2015 at 02:08:31PM +0200, Christoffer Dall wrote:
> > diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> > index 2de9d2e..0eeb4f09 100644
> > --- a/arch/arm64/mm/hugetlbpage.c
> > +++ b/arch/arm64/mm/hugetlbpage.c
> > @@ -40,13 +40,13 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
> >
> > int pmd_huge(pmd_t pmd)
> > {
> > - return !(pmd_val(pmd) & PMD_TABLE_BIT);
> > + return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
> > }
> >
> > int pud_huge(pud_t pud)
> > {
> > #ifndef __PAGETABLE_PMD_FOLDED
> > - return !(pud_val(pud) & PUD_TABLE_BIT);
> > + return pud_val(pud) && !(pud_val(pud) & PUD_TABLE_BIT);
> > #else
> > return 0;
> > #endif
>
> Thanks for the patch, I'll add the acks/reviews and Fixes: tags.
>
> (and I think I'll change pmd_val to pmd_present, same for pud; no
> functional difference)
A related question - can we ever have PROT_NONE on a huge pmd? I'll
leave this patch with pmd_val for now, it matches pmd_trans_huge().
--
Catalin
^ permalink raw reply [flat|nested] 14+ messages in thread* Re: [PATCH] arm64: Don't report clear pmds and puds as huge
2015-07-01 13:28 ` Catalin Marinas
@ 2015-07-01 13:56 ` Steve Capper
-1 siblings, 0 replies; 14+ messages in thread
From: Steve Capper @ 2015-07-01 13:56 UTC (permalink / raw)
To: Catalin Marinas
Cc: Christoffer Dall, Dirk Müller, Marc Zyngier, Alexander Graf,
stable, kvmarm, linux-arm-kernel@lists.infradead.org
On 1 July 2015 at 14:28, Catalin Marinas <catalin.marinas@arm.com> wrote:
> On Wed, Jul 01, 2015 at 02:18:31PM +0100, Catalin Marinas wrote:
>> On Wed, Jul 01, 2015 at 02:08:31PM +0200, Christoffer Dall wrote:
>> > diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
>> > index 2de9d2e..0eeb4f09 100644
>> > --- a/arch/arm64/mm/hugetlbpage.c
>> > +++ b/arch/arm64/mm/hugetlbpage.c
>> > @@ -40,13 +40,13 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
>> >
>> > int pmd_huge(pmd_t pmd)
>> > {
>> > - return !(pmd_val(pmd) & PMD_TABLE_BIT);
>> > + return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
>> > }
>> >
>> > int pud_huge(pud_t pud)
>> > {
>> > #ifndef __PAGETABLE_PMD_FOLDED
>> > - return !(pud_val(pud) & PUD_TABLE_BIT);
>> > + return pud_val(pud) && !(pud_val(pud) & PUD_TABLE_BIT);
>> > #else
>> > return 0;
>> > #endif
>>
>> Thanks for the patch, I'll add the acks/reviews and Fixes: tags.
>>
>> (and I think I'll change pmd_val to pmd_present, same for pud; no
>> functional difference)
>
> A related question - can we ever have PROT_NONE on a huge pmd? I'll
> leave this patch with pmd_val for now, it matches pmd_trans_huge().
Yes PROT_NONE can be used. I have a test case for it in libhugetlbfs
(for HugeTLB) and for THP at:
https://git.linaro.org/people/steve.capper/memory-tests.git
They worked last time I touched them ;-).
Cheers,
--
Steve
>
> --
> Catalin
^ permalink raw reply [flat|nested] 14+ messages in thread* [PATCH] arm64: Don't report clear pmds and puds as huge
@ 2015-07-01 13:56 ` Steve Capper
0 siblings, 0 replies; 14+ messages in thread
From: Steve Capper @ 2015-07-01 13:56 UTC (permalink / raw)
To: linux-arm-kernel
On 1 July 2015 at 14:28, Catalin Marinas <catalin.marinas@arm.com> wrote:
> On Wed, Jul 01, 2015 at 02:18:31PM +0100, Catalin Marinas wrote:
>> On Wed, Jul 01, 2015 at 02:08:31PM +0200, Christoffer Dall wrote:
>> > diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
>> > index 2de9d2e..0eeb4f09 100644
>> > --- a/arch/arm64/mm/hugetlbpage.c
>> > +++ b/arch/arm64/mm/hugetlbpage.c
>> > @@ -40,13 +40,13 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
>> >
>> > int pmd_huge(pmd_t pmd)
>> > {
>> > - return !(pmd_val(pmd) & PMD_TABLE_BIT);
>> > + return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
>> > }
>> >
>> > int pud_huge(pud_t pud)
>> > {
>> > #ifndef __PAGETABLE_PMD_FOLDED
>> > - return !(pud_val(pud) & PUD_TABLE_BIT);
>> > + return pud_val(pud) && !(pud_val(pud) & PUD_TABLE_BIT);
>> > #else
>> > return 0;
>> > #endif
>>
>> Thanks for the patch, I'll add the acks/reviews and Fixes: tags.
>>
>> (and I think I'll change pmd_val to pmd_present, same for pud; no
>> functional difference)
>
> A related question - can we ever have PROT_NONE on a huge pmd? I'll
> leave this patch with pmd_val for now, it matches pmd_trans_huge().
Yes PROT_NONE can be used. I have a test case for it in libhugetlbfs
(for HugeTLB) and for THP at:
https://git.linaro.org/people/steve.capper/memory-tests.git
They worked last time I touched them ;-).
Cheers,
--
Steve
>
> --
> Catalin
^ permalink raw reply [flat|nested] 14+ messages in thread