Re: [BISECTED] Linux 3.12.7 introduces page map handling regression
From: Elena Ufimtseva
Date: Tue Feb 04 2014 - 01:58:46 EST
On Sun, Jan 26, 2014 at 1:02 PM, Elena Ufimtseva <ufimtseva@xxxxxxxxx> wrote:
> On Fri, Jan 24, 2014 at 8:38 AM, Mel Gorman <mgorman@xxxxxxx> wrote:
>> On Thu, Jan 23, 2014 at 11:23:37AM -0500, Elena Ufimtseva wrote:
>>> >> >> <SNIP>
>>> >> >>
>>> >> >> This dump doesn't look dramatically different, either.
>>> >> >>
>>> >> >>>
>>> >> >>> The other question is - how is AutoNUMA running when it is not enabled?
>>> >> >>> Shouldn't those _PAGE_NUMA ops be nops when AutoNUMA hasn't even been
>>> >> >>> turned on?
>>> >> >>
>>> >> >>
>>> >> >> Well, NUMA_BALANCING is enabled in the kernel config[1], but I presume you
>>> >> >> mean not enabled at runtime?
>>> >> >>
>>> >> >> [1]
>>> >> >> http://git.uplinklabs.net/snoonan/projects/archlinux/ec2/ec2-packages.git/tree/linux-ec2/config.x86_64
>>> >>
>>> >>
>>> >>
>>> >> --
>>> >> Elena
>>>
>>> I was able to reproduce this consistently, also with the latest mm
>>> patches from yesterday.
>>> Can you please try this:
>>>
>>
>> Thanks Elena,
>>
>>> diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
>>> index ce563be..76dcf96 100644
>>> --- a/arch/x86/xen/mmu.c
>>> +++ b/arch/x86/xen/mmu.c
>>> @@ -365,7 +365,7 @@ void xen_ptep_modify_prot_commit(struct mm_struct
>>> *mm, unsigned long addr,
>>> /* Assume pteval_t is equivalent to all the other *val_t types. */
>>> static pteval_t pte_mfn_to_pfn(pteval_t val)
>>> {
>>> - if (val & _PAGE_PRESENT) {
>>> + if ((val & _PAGE_PRESENT) || ((val &
>>> (_PAGE_NUMA|_PAGE_PRESENT)) == _PAGE_NUMA)) {
>>> unsigned long mfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
>>> unsigned long pfn = mfn_to_pfn(mfn);
>>>
>>> @@ -381,7 +381,7 @@ static pteval_t pte_mfn_to_pfn(pteval_t val)
>>>
>>> static pteval_t pte_pfn_to_mfn(pteval_t val)
>>> {
>>> - if (val & _PAGE_PRESENT) {
>>> + if ((val & _PAGE_PRESENT) || ((val &
>>> (_PAGE_NUMA|_PAGE_PRESENT)) == _PAGE_NUMA)) {
>>> unsigned long pfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
>>> pteval_t flags = val & PTE_FLAGS_MASK;
>>> unsigned long mfn;
>>
>> Would reusing pte_present be an option? Ordinarily I expect that
>> PAGE_NUMA/PAGE_PROTNONE is only set if PAGE_PRESENT is not set and pte_present
>> is defined as
>>
>> static inline int pte_present(pte_t a)
>> {
>> return pte_flags(a) & (_PAGE_PRESENT | _PAGE_PROTNONE |
>> _PAGE_NUMA);
>> }
>>
>> So it looks like it work work. Of course it would need to be split to
>> reuse it within xen if pte_present was split to have a pteval_present
>> helper like so
>>
>> static inline int pteval_present(pteval_t val)
>> {
>> /*
>> * Yes Linus, _PAGE_PROTNONE == _PAGE_NUMA. Expressing it this
>> * way clearly states that the intent is that a protnone and numa
>> * hinting ptes are considered present for the purposes of
>> * pagetable operations like zapping, protection changes, gup etc.
>> */
>> return val & (_PAGE_PRESENT | _PAGE_PROTNONE | _PAGE_NUMA);
>> }
>>
>> static inline int pte_present(pte_t pte)
>> {
>> return pteval_present(pte_flags(pte))
>> }
>>
>> If Xen is doing some other tricks with _PAGE_PRESENT then it might be
>> ruled out as an option. If so, then maybe it could still be made a
>> little clearer for future reference?
>
> Yes, sure, it should work, I tried it.
> Thank you Mel.
>
>>
>>
>> diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
>> index c1d406f..ff621de 100644
>> --- a/arch/x86/xen/mmu.c
>> +++ b/arch/x86/xen/mmu.c
>> @@ -365,7 +365,7 @@ void xen_ptep_modify_prot_commit(struct mm_struct *mm, unsigned long addr,
>> /* Assume pteval_t is equivalent to all the other *val_t types. */
>> static pteval_t pte_mfn_to_pfn(pteval_t val)
>> {
>> - if (val & _PAGE_PRESENT) {
>> + if ((val & _PAGE_PRESENT) || pteval_numa(val)) {
>> unsigned long mfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
>> unsigned long pfn = mfn_to_pfn(mfn);
>>
>> @@ -381,7 +381,7 @@ static pteval_t pte_mfn_to_pfn(pteval_t val)
>>
>> static pteval_t pte_pfn_to_mfn(pteval_t val)
>> {
>> - if (val & _PAGE_PRESENT) {
>> + if ((val & _PAGE_PRESENT) || pteval_numa(val)) {
>> unsigned long pfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
>> pteval_t flags = val & PTE_FLAGS_MASK;
>> unsigned long mfn;
>> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
>> index 8e4f41d..693fe00 100644
>> --- a/include/asm-generic/pgtable.h
>> +++ b/include/asm-generic/pgtable.h
>> @@ -654,10 +654,14 @@ static inline int pmd_trans_unstable(pmd_t *pmd)
>> * (because _PAGE_PRESENT is not set).
>> */
>> #ifndef pte_numa
>> +static inline int pteval_numa(pteval_t pteval)
>> +{
>> + return (pteval & (_PAGE_NUMA|_PAGE_PRESENT)) == _PAGE_NUMA;
>> +}
>> +
>> static inline int pte_numa(pte_t pte)
>> {
>> - return (pte_flags(pte) &
>> - (_PAGE_NUMA|_PAGE_PRESENT)) == _PAGE_NUMA;
>> + return pteval_numa(pte_flags(pte));
>> }
>> #endif
>>
>
>
>
> --
> Elena
Here are two variants of this change . First one adds check for
_PAGE_NUMA flag in xen pte translations.
Second adds proposed by Mel pteval_present (comments are left
untouched :) and respective patch for xen pte translation that
uses pteval_present.
Mel, you can pick any of these two if they look fine and xen
maintainers are ok with the xen change (Konrad, David?)
Subject: [PATCH] xen: add _PAGE_NUMA for pte translations
xen: add _PAGE_NUMA for pte translations
Adds check in xen guest pte addresses translations for
_PAGE_NUMA flag. This resolves reported issues and will
be essential for NUMA support in xen guest with future
vNUMA patches.
Signed-off-by: Elena Ufimtseva <ufimtseva@xxxxxxxxx>
---
arch/x86/xen/mmu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 2423ef0..c804d58 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -365,7 +365,7 @@ void xen_ptep_modify_prot_commit(struct mm_struct
*mm, unsigned long addr,
/* Assume pteval_t is equivalent to all the other *val_t types. */
static pteval_t pte_mfn_to_pfn(pteval_t val)
{
- if (val & _PAGE_PRESENT) {
+ if ((val & _PAGE_PRESENT) || (val & (_PAGE_NUMA|_PAGE_PRESENT))) {
unsigned long mfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
unsigned long pfn = mfn_to_pfn(mfn);
@@ -381,7 +381,7 @@ static pteval_t pte_mfn_to_pfn(pteval_t val)
static pteval_t pte_pfn_to_mfn(pteval_t val)
{
- if (val & _PAGE_PRESENT) {
+ if ((val & _PAGE_PRESENT) || (val & (_PAGE_NUMA|_PAGE_PRESENT))) {
unsigned long pfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
pteval_t flags = val & PTE_FLAGS_MASK;
unsigned long mfn;
--
1.7.10.4
Subject: [PATCH] mm: adds pteval_present
As suggested by Mel Gorman in https://lkml.org/lkml/2014/1/24/174.
Adds pteval_present to clarify that hinting ptes are considered present
for the purposes of pagetable operations like zapping, protection changes,
gup etc.
Signed-off-by: Elena Ufimtseva <ufimtseva@xxxxxxxxx>
---
arch/x86/include/asm/pgtable.h | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index bbc8b12..205b00d 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -445,10 +445,20 @@ static inline int pte_same(pte_t a, pte_t b)
return a.pte == b.pte;
}
+static inline int pteval_present(pteval_t pteval)
+{
+ /*
+ * Yes Linus, _PAGE_PROTNONE == _PAGE_NUMA. Expressing it this
+ * way clearly states that the intent is that a protnone and numa
+ * hinting ptes are considered present for the purposes of
+ * pagetable operations like zapping, protection changes, gup etc.
+ */
+ return pteval & (_PAGE_PRESENT | _PAGE_PROTNONE | _PAGE_NUMA);
+}
+
static inline int pte_present(pte_t a)
{
- return pte_flags(a) & (_PAGE_PRESENT | _PAGE_PROTNONE |
- _PAGE_NUMA);
+ return pteval_present(pte_flags(a));
}
#define pte_accessible pte_accessible
--
1.7.10.4
Subject: [PATCH] xen: use pteval_present for xen pte translations
Uses pteval_present for xen pte translations as sugested
by Mel Gorman in https://lkml.org/lkml/2014/1/24/174.
This also takes into account _PAGE_NUMA flag.
Signed-off-by: Elena Ufimtseva <ufimtseva@xxxxxxxxx>
---
arch/x86/xen/mmu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 2423ef0..256282e 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -365,7 +365,7 @@ void xen_ptep_modify_prot_commit(struct mm_struct
*mm, unsigned long addr,
/* Assume pteval_t is equivalent to all the other *val_t types. */
static pteval_t pte_mfn_to_pfn(pteval_t val)
{
- if (val & _PAGE_PRESENT) {
+ if (pteval_present(val)) {
unsigned long mfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
unsigned long pfn = mfn_to_pfn(mfn);
@@ -381,7 +381,7 @@ static pteval_t pte_mfn_to_pfn(pteval_t val)
static pteval_t pte_pfn_to_mfn(pteval_t val)
{
- if (val & _PAGE_PRESENT) {
+ if (pteval_present(val)) {
unsigned long pfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
pteval_t flags = val & PTE_FLAGS_MASK;
unsigned long mfn;
--
1.7.10.4
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