* [PATCH] Fix generic hugetlb pte check return type.
@ 2013-10-02 18:25 ` David Miller
0 siblings, 0 replies; 8+ messages in thread
From: David Miller @ 2013-10-02 18:25 UTC (permalink / raw)
To: sparclinux; +Cc: linux-arch, linux-kernel
The include/asm-generic/hugetlb.h stubs that just vector huge_pte_*()
calls to the pte_*() implementations won't work in certain situations.
x86 and sparc, for example, return "unsigned long" from the bit
checks, and just go "return pte_val(pte) & PTE_BIT_FOO;"
But since huge_pte_*() returns 'int', if any high bits on 64-bit are
relevant, they get chopped off.
The net effect is that we can loop forever trying to COW a huge page,
because the huge_pte_write() check signals false all the time.
Reported-by: Gurudas Pai <gurudas.pai@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
Anyone mind if I push this through the sparc tree?
diff --git a/include/asm-generic/hugetlb.h b/include/asm-generic/hugetlb.h
index d06079c..99b490b 100644
--- a/include/asm-generic/hugetlb.h
+++ b/include/asm-generic/hugetlb.h
@@ -6,12 +6,12 @@ static inline pte_t mk_huge_pte(struct page *page, pgprot_t pgprot)
return mk_pte(page, pgprot);
}
-static inline int huge_pte_write(pte_t pte)
+static inline unsigned long huge_pte_write(pte_t pte)
{
return pte_write(pte);
}
-static inline int huge_pte_dirty(pte_t pte)
+static inline unsigned long huge_pte_dirty(pte_t pte)
{
return pte_dirty(pte);
}
^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH] Fix generic hugetlb pte check return type.
@ 2013-10-02 18:25 ` David Miller
0 siblings, 0 replies; 8+ messages in thread
From: David Miller @ 2013-10-02 18:25 UTC (permalink / raw)
To: sparclinux; +Cc: linux-arch, linux-kernel
The include/asm-generic/hugetlb.h stubs that just vector huge_pte_*()
calls to the pte_*() implementations won't work in certain situations.
x86 and sparc, for example, return "unsigned long" from the bit
checks, and just go "return pte_val(pte) & PTE_BIT_FOO;"
But since huge_pte_*() returns 'int', if any high bits on 64-bit are
relevant, they get chopped off.
The net effect is that we can loop forever trying to COW a huge page,
because the huge_pte_write() check signals false all the time.
Reported-by: Gurudas Pai <gurudas.pai@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
Anyone mind if I push this through the sparc tree?
diff --git a/include/asm-generic/hugetlb.h b/include/asm-generic/hugetlb.h
index d06079c..99b490b 100644
--- a/include/asm-generic/hugetlb.h
+++ b/include/asm-generic/hugetlb.h
@@ -6,12 +6,12 @@ static inline pte_t mk_huge_pte(struct page *page, pgprot_t pgprot)
return mk_pte(page, pgprot);
}
-static inline int huge_pte_write(pte_t pte)
+static inline unsigned long huge_pte_write(pte_t pte)
{
return pte_write(pte);
}
-static inline int huge_pte_dirty(pte_t pte)
+static inline unsigned long huge_pte_dirty(pte_t pte)
{
return pte_dirty(pte);
}
^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH] Fix generic hugetlb pte check return type.
2013-10-02 18:25 ` David Miller
@ 2013-10-02 22:34 ` David Rientjes
-1 siblings, 0 replies; 8+ messages in thread
From: David Rientjes @ 2013-10-02 22:34 UTC (permalink / raw)
To: David Miller; +Cc: sparclinux, linux-arch, linux-kernel
On Wed, 2 Oct 2013, David Miller wrote:
> The include/asm-generic/hugetlb.h stubs that just vector huge_pte_*()
> calls to the pte_*() implementations won't work in certain situations.
>
> x86 and sparc, for example, return "unsigned long" from the bit
> checks, and just go "return pte_val(pte) & PTE_BIT_FOO;"
>
x86 should be safe since it's known that both _PAGE_BIT_RW and
_PAGE_BIT_DIRTY are <= 32.
> But since huge_pte_*() returns 'int', if any high bits on 64-bit are
> relevant, they get chopped off.
>
> The net effect is that we can loop forever trying to COW a huge page,
> because the huge_pte_write() check signals false all the time.
>
> Reported-by: Gurudas Pai <gurudas.pai@oracle.com>
> Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: David Rientjes <rientjes@google.com>
> ---
>
> Anyone mind if I push this through the sparc tree?
>
Makes sense since it's the only arch that appears affected.
> diff --git a/include/asm-generic/hugetlb.h b/include/asm-generic/hugetlb.h
> index d06079c..99b490b 100644
> --- a/include/asm-generic/hugetlb.h
> +++ b/include/asm-generic/hugetlb.h
> @@ -6,12 +6,12 @@ static inline pte_t mk_huge_pte(struct page *page, pgprot_t pgprot)
> return mk_pte(page, pgprot);
> }
>
> -static inline int huge_pte_write(pte_t pte)
> +static inline unsigned long huge_pte_write(pte_t pte)
> {
> return pte_write(pte);
> }
>
> -static inline int huge_pte_dirty(pte_t pte)
> +static inline unsigned long huge_pte_dirty(pte_t pte)
> {
> return pte_dirty(pte);
> }
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] Fix generic hugetlb pte check return type.
@ 2013-10-02 22:34 ` David Rientjes
0 siblings, 0 replies; 8+ messages in thread
From: David Rientjes @ 2013-10-02 22:34 UTC (permalink / raw)
To: David Miller; +Cc: sparclinux, linux-arch, linux-kernel
On Wed, 2 Oct 2013, David Miller wrote:
> The include/asm-generic/hugetlb.h stubs that just vector huge_pte_*()
> calls to the pte_*() implementations won't work in certain situations.
>
> x86 and sparc, for example, return "unsigned long" from the bit
> checks, and just go "return pte_val(pte) & PTE_BIT_FOO;"
>
x86 should be safe since it's known that both _PAGE_BIT_RW and
_PAGE_BIT_DIRTY are <= 32.
> But since huge_pte_*() returns 'int', if any high bits on 64-bit are
> relevant, they get chopped off.
>
> The net effect is that we can loop forever trying to COW a huge page,
> because the huge_pte_write() check signals false all the time.
>
> Reported-by: Gurudas Pai <gurudas.pai@oracle.com>
> Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: David Rientjes <rientjes@google.com>
> ---
>
> Anyone mind if I push this through the sparc tree?
>
Makes sense since it's the only arch that appears affected.
> diff --git a/include/asm-generic/hugetlb.h b/include/asm-generic/hugetlb.h
> index d06079c..99b490b 100644
> --- a/include/asm-generic/hugetlb.h
> +++ b/include/asm-generic/hugetlb.h
> @@ -6,12 +6,12 @@ static inline pte_t mk_huge_pte(struct page *page, pgprot_t pgprot)
> return mk_pte(page, pgprot);
> }
>
> -static inline int huge_pte_write(pte_t pte)
> +static inline unsigned long huge_pte_write(pte_t pte)
> {
> return pte_write(pte);
> }
>
> -static inline int huge_pte_dirty(pte_t pte)
> +static inline unsigned long huge_pte_dirty(pte_t pte)
> {
> return pte_dirty(pte);
> }
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] Fix generic hugetlb pte check return type.
2013-10-02 22:34 ` David Rientjes
@ 2013-10-02 23:59 ` David Miller
-1 siblings, 0 replies; 8+ messages in thread
From: David Miller @ 2013-10-02 23:59 UTC (permalink / raw)
To: rientjes; +Cc: sparclinux, linux-arch, linux-kernel
From: David Rientjes <rientjes@google.com>
Date: Wed, 2 Oct 2013 15:34:48 -0700 (PDT)
> On Wed, 2 Oct 2013, David Miller wrote:
>
> Acked-by: David Rientjes <rientjes@google.com>
>
>> ---
>>
>> Anyone mind if I push this through the sparc tree?
>>
>
> Makes sense since it's the only arch that appears affected.
Ok, thanks for reviewing.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] Fix generic hugetlb pte check return type.
@ 2013-10-02 23:59 ` David Miller
0 siblings, 0 replies; 8+ messages in thread
From: David Miller @ 2013-10-02 23:59 UTC (permalink / raw)
To: rientjes; +Cc: sparclinux, linux-arch, linux-kernel
From: David Rientjes <rientjes@google.com>
Date: Wed, 2 Oct 2013 15:34:48 -0700 (PDT)
> On Wed, 2 Oct 2013, David Miller wrote:
>
> Acked-by: David Rientjes <rientjes@google.com>
>
>> ---
>>
>> Anyone mind if I push this through the sparc tree?
>>
>
> Makes sense since it's the only arch that appears affected.
Ok, thanks for reviewing.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] Fix generic hugetlb pte check return type.
2013-10-02 18:25 ` David Miller
@ 2013-10-03 8:54 ` David Howells
-1 siblings, 0 replies; 8+ messages in thread
From: David Howells @ 2013-10-03 8:54 UTC (permalink / raw)
To: David Miller; +Cc: dhowells, sparclinux, linux-arch, linux-kernel
David Miller <davem@davemloft.net> wrote:
> The include/asm-generic/hugetlb.h stubs that just vector huge_pte_*()
> calls to the pte_*() implementations won't work in certain situations.
>
> x86 and sparc, for example, return "unsigned long" from the bit
> checks, and just go "return pte_val(pte) & PTE_BIT_FOO;"
>
> But since huge_pte_*() returns 'int', if any high bits on 64-bit are
> relevant, they get chopped off.
>
> The net effect is that we can loop forever trying to COW a huge page,
> because the huge_pte_write() check signals false all the time.
>
> Reported-by: Gurudas Pai <gurudas.pai@oracle.com>
> Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: David Howells <dhowells@redhat.com>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] Fix generic hugetlb pte check return type.
@ 2013-10-03 8:54 ` David Howells
0 siblings, 0 replies; 8+ messages in thread
From: David Howells @ 2013-10-03 8:54 UTC (permalink / raw)
To: David Miller; +Cc: dhowells, sparclinux, linux-arch, linux-kernel
David Miller <davem@davemloft.net> wrote:
> The include/asm-generic/hugetlb.h stubs that just vector huge_pte_*()
> calls to the pte_*() implementations won't work in certain situations.
>
> x86 and sparc, for example, return "unsigned long" from the bit
> checks, and just go "return pte_val(pte) & PTE_BIT_FOO;"
>
> But since huge_pte_*() returns 'int', if any high bits on 64-bit are
> relevant, they get chopped off.
>
> The net effect is that we can loop forever trying to COW a huge page,
> because the huge_pte_write() check signals false all the time.
>
> Reported-by: Gurudas Pai <gurudas.pai@oracle.com>
> Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: David Howells <dhowells@redhat.com>
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2013-10-03 8:54 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2013-10-02 18:25 [PATCH] Fix generic hugetlb pte check return type David Miller
2013-10-02 18:25 ` David Miller
2013-10-02 22:34 ` David Rientjes
2013-10-02 22:34 ` David Rientjes
2013-10-02 23:59 ` David Miller
2013-10-02 23:59 ` David Miller
2013-10-03 8:54 ` David Howells
2013-10-03 8:54 ` David Howells
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