* [PATCH] powerpc: Fix bad pmd error with book3E config
@ 2013-06-12 10:30 Aneesh Kumar K.V
2013-06-12 20:33 ` Scott Wood
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Aneesh Kumar K.V @ 2013-06-12 10:30 UTC (permalink / raw)
To: benh, scottwood; +Cc: linuxppc-dev, Aneesh Kumar K.V
From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Book3E uses the hugepd at PMD level and don't encode pte directly
at the pmd level. So it will find the lower bits of pmd set
and the pmd_bad check throws error. Infact the current code
will never take the free_hugepd_range call at all because it will
clear the pmd if it find a hugepd pointer.
Reported-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
arch/powerpc/mm/hugetlbpage.c | 29 ++++++++++++++++++-----------
1 file changed, 18 insertions(+), 11 deletions(-)
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index f2f01fd..0d3d3ee 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -536,19 +536,26 @@ static void hugetlb_free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
do {
pmd = pmd_offset(pud, addr);
next = pmd_addr_end(addr, end);
- if (pmd_none_or_clear_bad(pmd))
- continue;
+ if (!is_hugepd(pmd)) {
+ /*
+ * if it is not hugepd pointer, we should already find
+ * it cleared.
+ */
+ if (!pmd_none_or_clear_bad(pmd))
+ WARN_ON(1);
+ } else {
#ifdef CONFIG_PPC_FSL_BOOK3E
- /*
- * Increment next by the size of the huge mapping since
- * there may be more than one entry at this level for a
- * single hugepage, but all of them point to
- * the same kmem cache that holds the hugepte.
- */
- next = addr + (1 << hugepd_shift(*(hugepd_t *)pmd));
+ /*
+ * Increment next by the size of the huge mapping since
+ * there may be more than one entry at this level for a
+ * single hugepage, but all of them point to
+ * the same kmem cache that holds the hugepte.
+ */
+ next = addr + (1 << hugepd_shift(*(hugepd_t *)pmd));
#endif
- free_hugepd_range(tlb, (hugepd_t *)pmd, PMD_SHIFT,
- addr, next, floor, ceiling);
+ free_hugepd_range(tlb, (hugepd_t *)pmd, PMD_SHIFT,
+ addr, next, floor, ceiling);
+ }
} while (addr = next, addr != end);
start &= PUD_MASK;
--
1.8.1.2
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] powerpc: Fix bad pmd error with book3E config
2013-06-12 10:30 [PATCH] powerpc: Fix bad pmd error with book3E config Aneesh Kumar K.V
@ 2013-06-12 20:33 ` Scott Wood
2013-06-18 13:02 ` Aneesh Kumar K.V
2013-06-19 5:48 ` Michael Neuling
2 siblings, 0 replies; 6+ messages in thread
From: Scott Wood @ 2013-06-12 20:33 UTC (permalink / raw)
To: Aneesh Kumar K.V; +Cc: linuxppc-dev
On Wed, Jun 12, 2013 at 04:00:04PM +0530, Aneesh Kumar K.V wrote:
> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
>
> Book3E uses the hugepd at PMD level and don't encode pte directly
> at the pmd level. So it will find the lower bits of pmd set
> and the pmd_bad check throws error. Infact the current code
> will never take the free_hugepd_range call at all because it will
> clear the pmd if it find a hugepd pointer.
>
> Reported-by: Scott Wood <scottwood@freescale.com>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> ---
> arch/powerpc/mm/hugetlbpage.c | 29 ++++++++++++++++++-----------
> 1 file changed, 18 insertions(+), 11 deletions(-)
Thanks; this fixes the error for me.
-Scott
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] powerpc: Fix bad pmd error with book3E config
2013-06-12 10:30 [PATCH] powerpc: Fix bad pmd error with book3E config Aneesh Kumar K.V
2013-06-12 20:33 ` Scott Wood
@ 2013-06-18 13:02 ` Aneesh Kumar K.V
2013-06-19 5:48 ` Michael Neuling
2 siblings, 0 replies; 6+ messages in thread
From: Aneesh Kumar K.V @ 2013-06-18 13:02 UTC (permalink / raw)
To: benh, scottwood; +Cc: linuxppc-dev
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> writes:
> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
>
> Book3E uses the hugepd at PMD level and don't encode pte directly
> at the pmd level. So it will find the lower bits of pmd set
> and the pmd_bad check throws error. Infact the current code
> will never take the free_hugepd_range call at all because it will
> clear the pmd if it find a hugepd pointer.
>
> Reported-by: Scott Wood <scottwood@freescale.com>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Ben,
This is regression introduced by
e2b3d202d1dba8f3546ed28224ce485bc50010be
"powerpc: Switch 16GB and 16MB explicit hugepages to a different page table format"
and should go upstream in 3.10
$git describe --contains e2b3d202d1dba8f3546ed28224ce485bc50010be
v3.10-rc1~121^2~15
Without this path, we leak hugepd with all subarchs using old huge page
directory format.
-aneesh
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] powerpc: Fix bad pmd error with book3E config
2013-06-12 10:30 [PATCH] powerpc: Fix bad pmd error with book3E config Aneesh Kumar K.V
2013-06-12 20:33 ` Scott Wood
2013-06-18 13:02 ` Aneesh Kumar K.V
@ 2013-06-19 5:48 ` Michael Neuling
2013-06-19 6:22 ` Aneesh Kumar K.V
2 siblings, 1 reply; 6+ messages in thread
From: Michael Neuling @ 2013-06-19 5:48 UTC (permalink / raw)
To: Aneesh Kumar K.V; +Cc: scottwood, linuxppc-dev
Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> wrote:
> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
>
> Book3E uses the hugepd at PMD level and don't encode pte directly
> at the pmd level. So it will find the lower bits of pmd set
> and the pmd_bad check throws error. Infact the current code
> will never take the free_hugepd_range call at all because it will
> clear the pmd if it find a hugepd pointer.
>
Please explain what changes you are making. Currently you are only
describing what the issue is.
Also include which the SHA1 which caused the regression (ie
e2b3d202d1dba8f3546ed28224ce485bc50010be "powerpc: Switch 16GB and 16MB
explicit hugepages to a different page table format")
Mikey
> Reported-by: Scott Wood <scottwood@freescale.com>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> ---
> arch/powerpc/mm/hugetlbpage.c | 29 ++++++++++++++++++-----------
> 1 file changed, 18 insertions(+), 11 deletions(-)
>
> diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
> index f2f01fd..0d3d3ee 100644
> --- a/arch/powerpc/mm/hugetlbpage.c
> +++ b/arch/powerpc/mm/hugetlbpage.c
> @@ -536,19 +536,26 @@ static void hugetlb_free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
> do {
> pmd = pmd_offset(pud, addr);
> next = pmd_addr_end(addr, end);
> - if (pmd_none_or_clear_bad(pmd))
> - continue;
> + if (!is_hugepd(pmd)) {
> + /*
> + * if it is not hugepd pointer, we should already find
> + * it cleared.
> + */
> + if (!pmd_none_or_clear_bad(pmd))
> + WARN_ON(1);
How often are we going to hit this? Should this be a warn_on once or
even a bug_on?
Also just make it:
WARN_ON(!pmd_none_or_clear_bad(pmd))
Mikey
> + } else {
> #ifdef CONFIG_PPC_FSL_BOOK3E
> - /*
> - * Increment next by the size of the huge mapping since
> - * there may be more than one entry at this level for a
> - * single hugepage, but all of them point to
> - * the same kmem cache that holds the hugepte.
> - */
> - next = addr + (1 << hugepd_shift(*(hugepd_t *)pmd));
> + /*
> + * Increment next by the size of the huge mapping since
> + * there may be more than one entry at this level for a
> + * single hugepage, but all of them point to
> + * the same kmem cache that holds the hugepte.
> + */
> + next = addr + (1 << hugepd_shift(*(hugepd_t *)pmd));
> #endif
> - free_hugepd_range(tlb, (hugepd_t *)pmd, PMD_SHIFT,
> - addr, next, floor, ceiling);
> + free_hugepd_range(tlb, (hugepd_t *)pmd, PMD_SHIFT,
> + addr, next, floor, ceiling);
> + }
> } while (addr = next, addr != end);
>
> start &= PUD_MASK;
> --
> 1.8.1.2
>
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] powerpc: Fix bad pmd error with book3E config
2013-06-19 5:48 ` Michael Neuling
@ 2013-06-19 6:22 ` Aneesh Kumar K.V
2013-06-19 6:27 ` Michael Neuling
0 siblings, 1 reply; 6+ messages in thread
From: Aneesh Kumar K.V @ 2013-06-19 6:22 UTC (permalink / raw)
To: Michael Neuling; +Cc: scottwood, linuxppc-dev
Michael Neuling <mikey@neuling.org> writes:
> Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> wrote:
>
>> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
>>
>> Book3E uses the hugepd at PMD level and don't encode pte directly
>> at the pmd level. So it will find the lower bits of pmd set
>> and the pmd_bad check throws error. Infact the current code
>> will never take the free_hugepd_range call at all because it will
>> clear the pmd if it find a hugepd pointer.
>>
>
> Please explain what changes you are making. Currently you are only
> describing what the issue is.
will do
>
> Also include which the SHA1 which caused the regression (ie
> e2b3d202d1dba8f3546ed28224ce485bc50010be "powerpc: Switch 16GB and 16MB
> explicit hugepages to a different page table format")
will add
>
> Mikey
>
>> Reported-by: Scott Wood <scottwood@freescale.com>
>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>> ---
>> arch/powerpc/mm/hugetlbpage.c | 29 ++++++++++++++++++-----------
>> 1 file changed, 18 insertions(+), 11 deletions(-)
>>
>> diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
>> index f2f01fd..0d3d3ee 100644
>> --- a/arch/powerpc/mm/hugetlbpage.c
>> +++ b/arch/powerpc/mm/hugetlbpage.c
>> @@ -536,19 +536,26 @@ static void hugetlb_free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
>> do {
>> pmd = pmd_offset(pud, addr);
>> next = pmd_addr_end(addr, end);
>> - if (pmd_none_or_clear_bad(pmd))
>> - continue;
>> + if (!is_hugepd(pmd)) {
>> + /*
>> + * if it is not hugepd pointer, we should already find
>> + * it cleared.
>> + */
>> + if (!pmd_none_or_clear_bad(pmd))
>> + WARN_ON(1);
>
> How often are we going to hit this? Should this be a warn_on once or
> even a bug_on?
it should never happen. But i was thinking killing the system may a bit
too much, hence WARN_ON
>
> Also just make it:
> WARN_ON(!pmd_none_or_clear_bad(pmd))
>
will do
-aneesh
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] powerpc: Fix bad pmd error with book3E config
2013-06-19 6:22 ` Aneesh Kumar K.V
@ 2013-06-19 6:27 ` Michael Neuling
0 siblings, 0 replies; 6+ messages in thread
From: Michael Neuling @ 2013-06-19 6:27 UTC (permalink / raw)
To: Aneesh Kumar K.V; +Cc: scottwood, linuxppc-dev
Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> wrote:
> Michael Neuling <mikey@neuling.org> writes:
>
> > Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> wrote:
> >
> >> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
> >>
> >> Book3E uses the hugepd at PMD level and don't encode pte directly
> >> at the pmd level. So it will find the lower bits of pmd set
> >> and the pmd_bad check throws error. Infact the current code
> >> will never take the free_hugepd_range call at all because it will
> >> clear the pmd if it find a hugepd pointer.
> >>
> >
> > Please explain what changes you are making. Currently you are only
> > describing what the issue is.
>
> will do
>
> >
> > Also include which the SHA1 which caused the regression (ie
> > e2b3d202d1dba8f3546ed28224ce485bc50010be "powerpc: Switch 16GB and 16MB
> > explicit hugepages to a different page table format")
>
> will add
>
> >
> > Mikey
> >
> >> Reported-by: Scott Wood <scottwood@freescale.com>
> >> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> >> ---
> >> arch/powerpc/mm/hugetlbpage.c | 29 ++++++++++++++++++-----------
> >> 1 file changed, 18 insertions(+), 11 deletions(-)
> >>
> >> diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
> >> index f2f01fd..0d3d3ee 100644
> >> --- a/arch/powerpc/mm/hugetlbpage.c
> >> +++ b/arch/powerpc/mm/hugetlbpage.c
> >> @@ -536,19 +536,26 @@ static void hugetlb_free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
> >> do {
> >> pmd = pmd_offset(pud, addr);
> >> next = pmd_addr_end(addr, end);
> >> - if (pmd_none_or_clear_bad(pmd))
> >> - continue;
> >> + if (!is_hugepd(pmd)) {
> >> + /*
> >> + * if it is not hugepd pointer, we should already find
> >> + * it cleared.
> >> + */
> >> + if (!pmd_none_or_clear_bad(pmd))
> >> + WARN_ON(1);
> >
> > How often are we going to hit this? Should this be a warn_on once or
> > even a bug_on?
>
> it should never happen. But i was thinking killing the system may a bit
> too much, hence WARN_ON
Maybe WARN_ON_ONCE. If you do hit it once, you are going to hit it a
lot?
Mikey
>
> >
> > Also just make it:
> > WARN_ON(!pmd_none_or_clear_bad(pmd))
> >
>
> will do
>
> -aneesh
>
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2013-06-19 6:27 UTC | newest]
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2013-06-12 10:30 [PATCH] powerpc: Fix bad pmd error with book3E config Aneesh Kumar K.V
2013-06-12 20:33 ` Scott Wood
2013-06-18 13:02 ` Aneesh Kumar K.V
2013-06-19 5:48 ` Michael Neuling
2013-06-19 6:22 ` Aneesh Kumar K.V
2013-06-19 6:27 ` Michael Neuling
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