From: Zi Yan <[email protected]>
Add PUD-level TLB flush ops and teach page_vma_mapped_talk about 1GB
THPs.
Signed-off-by: Zi Yan <[email protected]>
---
arch/x86/include/asm/pgtable.h | 3 +++
arch/x86/mm/pgtable.c | 13 +++++++++++++
include/linux/mmu_notifier.h | 13 +++++++++++++
include/linux/pgtable.h | 14 ++++++++++++++
include/linux/rmap.h | 1 +
mm/page_vma_mapped.c | 33 +++++++++++++++++++++++++++++----
mm/rmap.c | 12 +++++++++---
7 files changed, 82 insertions(+), 7 deletions(-)
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 26255cac78c0..15334f5ba172 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -1127,6 +1127,9 @@ extern int pudp_test_and_clear_young(struct vm_area_struct *vma,
extern int pmdp_clear_flush_young(struct vm_area_struct *vma,
unsigned long address, pmd_t *pmdp);
+#define __HAVE_ARCH_PUDP_CLEAR_YOUNG_FLUSH
+extern int pudp_clear_flush_young(struct vm_area_struct *vma,
+ unsigned long address, pud_t *pudp);
#define pmd_write pmd_write
static inline int pmd_write(pmd_t pmd)
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 7be73aee6183..e4a2dffcc418 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -633,6 +633,19 @@ int pmdp_clear_flush_young(struct vm_area_struct *vma,
return young;
}
+int pudp_clear_flush_young(struct vm_area_struct *vma,
+ unsigned long address, pud_t *pudp)
+{
+ int young;
+
+ VM_BUG_ON(address & ~HPAGE_PUD_MASK);
+
+ young = pudp_test_and_clear_young(vma, address, pudp);
+ if (young)
+ flush_tlb_range(vma, address, address + HPAGE_PUD_SIZE);
+
+ return young;
+}
#endif
/**
diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index b8200782dede..4ffa179e654f 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -557,6 +557,19 @@ static inline void mmu_notifier_range_init_migrate(
__young; \
})
+#define pudp_clear_flush_young_notify(__vma, __address, __pudp) \
+({ \
+ int __young; \
+ struct vm_area_struct *___vma = __vma; \
+ unsigned long ___address = __address; \
+ __young = pudp_clear_flush_young(___vma, ___address, __pudp); \
+ __young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \
+ ___address, \
+ ___address + \
+ PUD_SIZE); \
+ __young; \
+})
+
#define ptep_clear_young_notify(__vma, __address, __ptep) \
({ \
int __young; \
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 255275d5b73e..8ef358c386af 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -240,6 +240,20 @@ static inline int pmdp_clear_flush_young(struct vm_area_struct *vma,
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#endif
+#ifndef __HAVE_ARCH_PUDP_CLEAR_YOUNG_FLUSH
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+extern int pudp_clear_flush_young(struct vm_area_struct *vma,
+ unsigned long address, pud_t *pudp);
+#else
+int pudp_clear_flush_young(struct vm_area_struct *vma,
+ unsigned long address, pud_t *pudp)
+{
+ BUILD_BUG();
+ return 0;
+}
+#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
+#endif
+
#ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR
static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
unsigned long address,
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 3a6adfa70fb0..0af61dd193d2 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -206,6 +206,7 @@ struct page_vma_mapped_walk {
struct page *page;
struct vm_area_struct *vma;
unsigned long address;
+ pud_t *pud;
pmd_t *pmd;
pte_t *pte;
spinlock_t *ptl;
diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index 5e77b269c330..d9d39ec06e21 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -145,9 +145,12 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
struct page *page = pvmw->page;
pgd_t *pgd;
p4d_t *p4d;
- pud_t *pud;
+ pud_t pude;
pmd_t pmde;
+ if (!pvmw->pte && !pvmw->pmd && pvmw->pud)
+ return not_found(pvmw);
+
/* The only possible pmd mapping has been handled on last iteration */
if (pvmw->pmd && !pvmw->pte)
return not_found(pvmw);
@@ -174,10 +177,31 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
p4d = p4d_offset(pgd, pvmw->address);
if (!p4d_present(*p4d))
return false;
- pud = pud_offset(p4d, pvmw->address);
- if (!pud_present(*pud))
+ pvmw->pud = pud_offset(p4d, pvmw->address);
+
+ /*
+ * Make sure the pud value isn't cached in a register by the
+ * compiler and used as a stale value after we've observed a
+ * subsequent update.
+ */
+ pude = READ_ONCE(*pvmw->pud);
+ if (pud_trans_huge(pude)) {
+ pvmw->ptl = pud_lock(mm, pvmw->pud);
+ if (likely(pud_trans_huge(*pvmw->pud))) {
+ if (pvmw->flags & PVMW_MIGRATION)
+ return not_found(pvmw);
+ if (pud_page(*pvmw->pud) != page)
+ return not_found(pvmw);
+ return true;
+ } else {
+ /* THP pud was split under us: handle on pmd level */
+ spin_unlock(pvmw->ptl);
+ pvmw->ptl = NULL;
+ }
+ } else if (!pud_present(pude))
return false;
- pvmw->pmd = pmd_offset(pud, pvmw->address);
+
+ pvmw->pmd = pmd_offset(pvmw->pud, pvmw->address);
/*
* Make sure the pmd value isn't cached in a register by the
* compiler and used as a stale value after we've observed a
@@ -213,6 +237,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
} else if (!pmd_present(pmde)) {
return false;
}
+
if (!map_pte(pvmw))
goto next_pte;
while (1) {
diff --git a/mm/rmap.c b/mm/rmap.c
index 10195a2421cf..77cec0658b76 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -803,9 +803,15 @@ static bool page_referenced_one(struct page *page, struct vm_area_struct *vma,
referenced++;
}
} else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
- if (pmdp_clear_flush_young_notify(vma, address,
- pvmw.pmd))
- referenced++;
+ if (pvmw.pmd) {
+ if (pmdp_clear_flush_young_notify(vma, address,
+ pvmw.pmd))
+ referenced++;
+ } else if (pvmw.pud) {
+ if (pudp_clear_flush_young_notify(vma, address,
+ pvmw.pud))
+ referenced++;
+ }
} else {
/* unexpected pmd-mapped page? */
WARN_ON_ONCE(1);
--
2.28.0
On 9 Sep 2020, at 10:09, Kirill A. Shutemov wrote:
> On Wed, Sep 02, 2020 at 02:06:17PM -0400, Zi Yan wrote:
>> From: Zi Yan <[email protected]>
>>
>> Add PUD-level TLB flush ops and teach page_vma_mapped_talk about 1GB
>> THPs.
>>
>> Signed-off-by: Zi Yan <[email protected]>
>> ---
>> arch/x86/include/asm/pgtable.h | 3 +++
>> arch/x86/mm/pgtable.c | 13 +++++++++++++
>> include/linux/mmu_notifier.h | 13 +++++++++++++
>> include/linux/pgtable.h | 14 ++++++++++++++
>> include/linux/rmap.h | 1 +
>> mm/page_vma_mapped.c | 33 +++++++++++++++++++++++++++++----
>> mm/rmap.c | 12 +++++++++---
>> 7 files changed, 82 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
>> index 26255cac78c0..15334f5ba172 100644
>> --- a/arch/x86/include/asm/pgtable.h
>> +++ b/arch/x86/include/asm/pgtable.h
>> @@ -1127,6 +1127,9 @@ extern int pudp_test_and_clear_young(struct vm_area_struct *vma,
>> extern int pmdp_clear_flush_young(struct vm_area_struct *vma,
>> unsigned long address, pmd_t *pmdp);
>>
>> +#define __HAVE_ARCH_PUDP_CLEAR_YOUNG_FLUSH
>> +extern int pudp_clear_flush_young(struct vm_area_struct *vma,
>> + unsigned long address, pud_t *pudp);
>>
>> #define pmd_write pmd_write
>> static inline int pmd_write(pmd_t pmd)
>> diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
>> index 7be73aee6183..e4a2dffcc418 100644
>> --- a/arch/x86/mm/pgtable.c
>> +++ b/arch/x86/mm/pgtable.c
>> @@ -633,6 +633,19 @@ int pmdp_clear_flush_young(struct vm_area_struct *vma,
>>
>> return young;
>> }
>> +int pudp_clear_flush_young(struct vm_area_struct *vma,
>> + unsigned long address, pud_t *pudp)
>> +{
>> + int young;
>> +
>> + VM_BUG_ON(address & ~HPAGE_PUD_MASK);
>> +
>> + young = pudp_test_and_clear_young(vma, address, pudp);
>> + if (young)
>> + flush_tlb_range(vma, address, address + HPAGE_PUD_SIZE);
>> +
>> + return young;
>> +}
>> #endif
>>
>> /**
>> diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
>> index b8200782dede..4ffa179e654f 100644
>> --- a/include/linux/mmu_notifier.h
>> +++ b/include/linux/mmu_notifier.h
>> @@ -557,6 +557,19 @@ static inline void mmu_notifier_range_init_migrate(
>> __young; \
>> })
>>
>> +#define pudp_clear_flush_young_notify(__vma, __address, __pudp) \
>> +({ \
>> + int __young; \
>> + struct vm_area_struct *___vma = __vma; \
>> + unsigned long ___address = __address; \
>> + __young = pudp_clear_flush_young(___vma, ___address, __pudp); \
>> + __young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \
>> + ___address, \
>> + ___address + \
>> + PUD_SIZE); \
>> + __young; \
>> +})
>> +
>> #define ptep_clear_young_notify(__vma, __address, __ptep) \
>> ({ \
>> int __young; \
>> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
>> index 255275d5b73e..8ef358c386af 100644
>> --- a/include/linux/pgtable.h
>> +++ b/include/linux/pgtable.h
>> @@ -240,6 +240,20 @@ static inline int pmdp_clear_flush_young(struct vm_area_struct *vma,
>> #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>> #endif
>>
>> +#ifndef __HAVE_ARCH_PUDP_CLEAR_YOUNG_FLUSH
>> +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
>> +extern int pudp_clear_flush_young(struct vm_area_struct *vma,
>> + unsigned long address, pud_t *pudp);
>> +#else
>> +int pudp_clear_flush_young(struct vm_area_struct *vma,
>> + unsigned long address, pud_t *pudp)
>> +{
>> + BUILD_BUG();
>> + return 0;
>> +}
>> +#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
>> +#endif
>> +
>> #ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR
>> static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
>> unsigned long address,
>> diff --git a/include/linux/rmap.h b/include/linux/rmap.h
>> index 3a6adfa70fb0..0af61dd193d2 100644
>> --- a/include/linux/rmap.h
>> +++ b/include/linux/rmap.h
>> @@ -206,6 +206,7 @@ struct page_vma_mapped_walk {
>> struct page *page;
>> struct vm_area_struct *vma;
>> unsigned long address;
>> + pud_t *pud;
>> pmd_t *pmd;
>> pte_t *pte;
>> spinlock_t *ptl;
>> diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
>> index 5e77b269c330..d9d39ec06e21 100644
>> --- a/mm/page_vma_mapped.c
>> +++ b/mm/page_vma_mapped.c
>> @@ -145,9 +145,12 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
>> struct page *page = pvmw->page;
>> pgd_t *pgd;
>> p4d_t *p4d;
>> - pud_t *pud;
>> + pud_t pude;
>> pmd_t pmde;
>>
>> + if (!pvmw->pte && !pvmw->pmd && pvmw->pud)
>> + return not_found(pvmw);
>> +
>> /* The only possible pmd mapping has been handled on last iteration */
>> if (pvmw->pmd && !pvmw->pte)
>> return not_found(pvmw);
>> @@ -174,10 +177,31 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
>> p4d = p4d_offset(pgd, pvmw->address);
>> if (!p4d_present(*p4d))
>> return false;
>> - pud = pud_offset(p4d, pvmw->address);
>> - if (!pud_present(*pud))
>> + pvmw->pud = pud_offset(p4d, pvmw->address);
>> +
>> + /*
>> + * Make sure the pud value isn't cached in a register by the
>> + * compiler and used as a stale value after we've observed a
>> + * subsequent update.
>> + */
>> + pude = READ_ONCE(*pvmw->pud);
>> + if (pud_trans_huge(pude)) {
>> + pvmw->ptl = pud_lock(mm, pvmw->pud);
>> + if (likely(pud_trans_huge(*pvmw->pud))) {
>> + if (pvmw->flags & PVMW_MIGRATION)
>> + return not_found(pvmw);
>> + if (pud_page(*pvmw->pud) != page)
>> + return not_found(pvmw);
>> + return true;
>> + } else {
>> + /* THP pud was split under us: handle on pmd level */
>> + spin_unlock(pvmw->ptl);
>> + pvmw->ptl = NULL;
>
> Hm. What makes you sure the pmd table is established here?
>
> I have not looked at PUD THP handling of MADV_DONTNEED yet, but for PMD
> THP can became pmd_none() at any point (unless ptl is locked).
You are right. I need to check pud_present here and only
go to pmd level when pud is present, otherwise just return with not_found.
Thanks.
>
>> + }
>> + } else if (!pud_present(pude))
>> return false;
>> - pvmw->pmd = pmd_offset(pud, pvmw->address);
>> +
>> + pvmw->pmd = pmd_offset(pvmw->pud, pvmw->address);
>> /*
>> * Make sure the pmd value isn't cached in a register by the
>> * compiler and used as a stale value after we've observed a
>> @@ -213,6 +237,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
>> } else if (!pmd_present(pmde)) {
>> return false;
>> }
>> +
>> if (!map_pte(pvmw))
>> goto next_pte;
>> while (1) {
>> diff --git a/mm/rmap.c b/mm/rmap.c
>
> Why?
>
The extra newline? Will remove it.
>> index 10195a2421cf..77cec0658b76 100644
>> --- a/mm/rmap.c
>> +++ b/mm/rmap.c
>> @@ -803,9 +803,15 @@ static bool page_referenced_one(struct page *page, struct vm_area_struct *vma,
>> referenced++;
>> }
>> } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
>> - if (pmdp_clear_flush_young_notify(vma, address,
>> - pvmw.pmd))
>> - referenced++;
>> + if (pvmw.pmd) {
>> + if (pmdp_clear_flush_young_notify(vma, address,
>> + pvmw.pmd))
>> + referenced++;
>> + } else if (pvmw.pud) {
>> + if (pudp_clear_flush_young_notify(vma, address,
>> + pvmw.pud))
>> + referenced++;
>> + }
>> } else {
>> /* unexpected pmd-mapped page? */
>> WARN_ON_ONCE(1);
>> --
>> 2.28.0
>>
>>
>
> --
> Kirill A. Shutemov
—
Best Regards,
Yan Zi
On Wed, Sep 02, 2020 at 02:06:17PM -0400, Zi Yan wrote:
> From: Zi Yan <[email protected]>
>
> Add PUD-level TLB flush ops and teach page_vma_mapped_talk about 1GB
> THPs.
>
> Signed-off-by: Zi Yan <[email protected]>
> ---
> arch/x86/include/asm/pgtable.h | 3 +++
> arch/x86/mm/pgtable.c | 13 +++++++++++++
> include/linux/mmu_notifier.h | 13 +++++++++++++
> include/linux/pgtable.h | 14 ++++++++++++++
> include/linux/rmap.h | 1 +
> mm/page_vma_mapped.c | 33 +++++++++++++++++++++++++++++----
> mm/rmap.c | 12 +++++++++---
> 7 files changed, 82 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
> index 26255cac78c0..15334f5ba172 100644
> --- a/arch/x86/include/asm/pgtable.h
> +++ b/arch/x86/include/asm/pgtable.h
> @@ -1127,6 +1127,9 @@ extern int pudp_test_and_clear_young(struct vm_area_struct *vma,
> extern int pmdp_clear_flush_young(struct vm_area_struct *vma,
> unsigned long address, pmd_t *pmdp);
>
> +#define __HAVE_ARCH_PUDP_CLEAR_YOUNG_FLUSH
> +extern int pudp_clear_flush_young(struct vm_area_struct *vma,
> + unsigned long address, pud_t *pudp);
>
> #define pmd_write pmd_write
> static inline int pmd_write(pmd_t pmd)
> diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
> index 7be73aee6183..e4a2dffcc418 100644
> --- a/arch/x86/mm/pgtable.c
> +++ b/arch/x86/mm/pgtable.c
> @@ -633,6 +633,19 @@ int pmdp_clear_flush_young(struct vm_area_struct *vma,
>
> return young;
> }
> +int pudp_clear_flush_young(struct vm_area_struct *vma,
> + unsigned long address, pud_t *pudp)
> +{
> + int young;
> +
> + VM_BUG_ON(address & ~HPAGE_PUD_MASK);
> +
> + young = pudp_test_and_clear_young(vma, address, pudp);
> + if (young)
> + flush_tlb_range(vma, address, address + HPAGE_PUD_SIZE);
> +
> + return young;
> +}
> #endif
>
> /**
> diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
> index b8200782dede..4ffa179e654f 100644
> --- a/include/linux/mmu_notifier.h
> +++ b/include/linux/mmu_notifier.h
> @@ -557,6 +557,19 @@ static inline void mmu_notifier_range_init_migrate(
> __young; \
> })
>
> +#define pudp_clear_flush_young_notify(__vma, __address, __pudp) \
> +({ \
> + int __young; \
> + struct vm_area_struct *___vma = __vma; \
> + unsigned long ___address = __address; \
> + __young = pudp_clear_flush_young(___vma, ___address, __pudp); \
> + __young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \
> + ___address, \
> + ___address + \
> + PUD_SIZE); \
> + __young; \
> +})
> +
> #define ptep_clear_young_notify(__vma, __address, __ptep) \
> ({ \
> int __young; \
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index 255275d5b73e..8ef358c386af 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -240,6 +240,20 @@ static inline int pmdp_clear_flush_young(struct vm_area_struct *vma,
> #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
> #endif
>
> +#ifndef __HAVE_ARCH_PUDP_CLEAR_YOUNG_FLUSH
> +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
> +extern int pudp_clear_flush_young(struct vm_area_struct *vma,
> + unsigned long address, pud_t *pudp);
> +#else
> +int pudp_clear_flush_young(struct vm_area_struct *vma,
> + unsigned long address, pud_t *pudp)
> +{
> + BUILD_BUG();
> + return 0;
> +}
> +#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
> +#endif
> +
> #ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR
> static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
> unsigned long address,
> diff --git a/include/linux/rmap.h b/include/linux/rmap.h
> index 3a6adfa70fb0..0af61dd193d2 100644
> --- a/include/linux/rmap.h
> +++ b/include/linux/rmap.h
> @@ -206,6 +206,7 @@ struct page_vma_mapped_walk {
> struct page *page;
> struct vm_area_struct *vma;
> unsigned long address;
> + pud_t *pud;
> pmd_t *pmd;
> pte_t *pte;
> spinlock_t *ptl;
> diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
> index 5e77b269c330..d9d39ec06e21 100644
> --- a/mm/page_vma_mapped.c
> +++ b/mm/page_vma_mapped.c
> @@ -145,9 +145,12 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
> struct page *page = pvmw->page;
> pgd_t *pgd;
> p4d_t *p4d;
> - pud_t *pud;
> + pud_t pude;
> pmd_t pmde;
>
> + if (!pvmw->pte && !pvmw->pmd && pvmw->pud)
> + return not_found(pvmw);
> +
> /* The only possible pmd mapping has been handled on last iteration */
> if (pvmw->pmd && !pvmw->pte)
> return not_found(pvmw);
> @@ -174,10 +177,31 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
> p4d = p4d_offset(pgd, pvmw->address);
> if (!p4d_present(*p4d))
> return false;
> - pud = pud_offset(p4d, pvmw->address);
> - if (!pud_present(*pud))
> + pvmw->pud = pud_offset(p4d, pvmw->address);
> +
> + /*
> + * Make sure the pud value isn't cached in a register by the
> + * compiler and used as a stale value after we've observed a
> + * subsequent update.
> + */
> + pude = READ_ONCE(*pvmw->pud);
> + if (pud_trans_huge(pude)) {
> + pvmw->ptl = pud_lock(mm, pvmw->pud);
> + if (likely(pud_trans_huge(*pvmw->pud))) {
> + if (pvmw->flags & PVMW_MIGRATION)
> + return not_found(pvmw);
> + if (pud_page(*pvmw->pud) != page)
> + return not_found(pvmw);
> + return true;
> + } else {
> + /* THP pud was split under us: handle on pmd level */
> + spin_unlock(pvmw->ptl);
> + pvmw->ptl = NULL;
Hm. What makes you sure the pmd table is established here?
I have not looked at PUD THP handling of MADV_DONTNEED yet, but for PMD
THP can became pmd_none() at any point (unless ptl is locked).
> + }
> + } else if (!pud_present(pude))
> return false;
> - pvmw->pmd = pmd_offset(pud, pvmw->address);
> +
> + pvmw->pmd = pmd_offset(pvmw->pud, pvmw->address);
> /*
> * Make sure the pmd value isn't cached in a register by the
> * compiler and used as a stale value after we've observed a
> @@ -213,6 +237,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
> } else if (!pmd_present(pmde)) {
> return false;
> }
> +
> if (!map_pte(pvmw))
> goto next_pte;
> while (1) {
> diff --git a/mm/rmap.c b/mm/rmap.c
Why?
> index 10195a2421cf..77cec0658b76 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -803,9 +803,15 @@ static bool page_referenced_one(struct page *page, struct vm_area_struct *vma,
> referenced++;
> }
> } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
> - if (pmdp_clear_flush_young_notify(vma, address,
> - pvmw.pmd))
> - referenced++;
> + if (pvmw.pmd) {
> + if (pmdp_clear_flush_young_notify(vma, address,
> + pvmw.pmd))
> + referenced++;
> + } else if (pvmw.pud) {
> + if (pudp_clear_flush_young_notify(vma, address,
> + pvmw.pud))
> + referenced++;
> + }
> } else {
> /* unexpected pmd-mapped page? */
> WARN_ON_ONCE(1);
> --
> 2.28.0
>
>
--
Kirill A. Shutemov