[RFC PATCH v3 2/3] mm: Add PUD level pagetable account

Baolin Wang
2022-06-30T11:11:36Z

Now the PUD level ptes are always protected by mm->page_table_lock,
which means no split pagetable lock needed. So the generic PUD level
pagetable pages allocation will not call pgtable_pte_page_ctor/dtor(),
that means we will miss to account PUD level pagetable pages.

Adding pagetable account by calling pgtable_page_inc() or
pgtable_page_dec() when allocating or freeing PUD level pagetable
pages to help to get an accurate pagetable accounting.

Moreover this patch will also mark the PUD level pagetable with PG_table
flag, which will help to do sanity validation in unpoison_memory() and
get more accurate pagetable accounting by /proc/kpageflags interface.

Meanwhile converting the architectures with using generic PUD pagatable
allocation to add corresponding pgtable_page_inc() or pgtable_page_dec()
to account PUD level pagetable.

Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
---
arch/arm64/include/asm/tlb.h | 5 ++++-
arch/loongarch/include/asm/pgalloc.h | 11 ++++++++---
arch/mips/include/asm/pgalloc.h | 11 ++++++++---
arch/s390/include/asm/tlb.h | 1 +
arch/x86/mm/pgtable.c | 5 ++++-
include/asm-generic/pgalloc.h | 12 ++++++++++--
6 files changed, 35 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h
index c995d1f..1772df9 100644
--- a/arch/arm64/include/asm/tlb.h
+++ b/arch/arm64/include/asm/tlb.h
@@ -94,7 +94,10 @@ static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
static inline void __pud_free_tlb(struct mmu_gather *tlb, pud_t *pudp,
unsigned long addr)
{
- tlb_remove_table(tlb, virt_to_page(pudp));
+ struct page *page = virt_to_page(pudp);
+
+ pgtable_page_dec(page);
+ tlb_remove_table(tlb, page);
}
#endif

diff --git a/arch/loongarch/include/asm/pgalloc.h b/arch/loongarch/include/asm/pgalloc.h
index b0a57b2..19bfe14 100644
--- a/arch/loongarch/include/asm/pgalloc.h
+++ b/arch/loongarch/include/asm/pgalloc.h
@@ -89,10 +89,15 @@ static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long address)
{
pud_t *pud;
+ struct page *page;

- pud = (pud_t *) __get_free_pages(GFP_KERNEL, PUD_ORDER);
- if (pud)
- pud_init((unsigned long)pud, (unsigned long)invalid_pmd_table);
+ page = alloc_pages(GFP_KERNEL, PUD_ORDER);
+ if (!page)
+ return NULL;
+
+ pgtable_page_inc(page);
+ pud = (pud_t *)page_address(page);
+ pud_init((unsigned long)pud, (unsigned long)invalid_pmd_table);
return pud;
}

diff --git a/arch/mips/include/asm/pgalloc.h b/arch/mips/include/asm/pgalloc.h
index 867e9c3..990f614 100644
--- a/arch/mips/include/asm/pgalloc.h
+++ b/arch/mips/include/asm/pgalloc.h
@@ -89,11 +89,16 @@ static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)

static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long address)
{
+ struct page *page;
pud_t *pud;

- pud = (pud_t *) __get_free_pages(GFP_KERNEL, PUD_ORDER);
- if (pud)
- pud_init((unsigned long)pud, (unsigned long)invalid_pmd_table);
+ page = alloc_pages(GFP_KERNEL, PUD_ORDER);
+ if (!page)
+ return NULL;
+
+ pgtable_page_inc(page);
+ pud = (pud_t *)page_address(page);
+ pud_init((unsigned long)pud, (unsigned long)invalid_pmd_table);
return pud;
}

diff --git a/arch/s390/include/asm/tlb.h b/arch/s390/include/asm/tlb.h
index fe6407f..744e2d7 100644
--- a/arch/s390/include/asm/tlb.h
+++ b/arch/s390/include/asm/tlb.h
@@ -125,6 +125,7 @@ static inline void pud_free_tlb(struct mmu_gather *tlb, pud_t *pud,
{
if (mm_pud_folded(tlb->mm))
return;
+ pgtable_page_dec(virt_to_page(pud));
tlb->mm->context.flush_mm = 1;
tlb->freed_tables = 1;
tlb->cleared_p4ds = 1;
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index a932d77..5e46e31 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -76,8 +76,11 @@ void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd)
#if CONFIG_PGTABLE_LEVELS > 3
void ___pud_free_tlb(struct mmu_gather *tlb, pud_t *pud)
{
+ struct page *page = virt_to_page(pud);
+
+ pgtable_page_dec(page);
paravirt_release_pud(__pa(pud) >> PAGE_SHIFT);
- paravirt_tlb_remove_table(tlb, virt_to_page(pud));
+ paravirt_tlb_remove_table(tlb, page);
}

#if CONFIG_PGTABLE_LEVELS > 4
diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h
index 977bea1..11350f7 100644
--- a/include/asm-generic/pgalloc.h
+++ b/include/asm-generic/pgalloc.h
@@ -149,11 +149,16 @@ static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)

static inline pud_t *__pud_alloc_one(struct mm_struct *mm, unsigned long addr)
{
+ struct page *page;
gfp_t gfp = GFP_PGTABLE_USER;

if (mm == &init_mm)
gfp = GFP_PGTABLE_KERNEL;
- return (pud_t *)get_zeroed_page(gfp);
+ page = alloc_pages(gfp, 0);
+ if (!page)
+ return NULL;
+ pgtable_page_inc(page);
+ return (pud_t *)page_address(page);
}

#ifndef __HAVE_ARCH_PUD_ALLOC_ONE
@@ -174,8 +179,11 @@ static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long addr)

static inline void __pud_free(struct mm_struct *mm, pud_t *pud)
{
+ struct page *page = virt_to_page(pud);
+
BUG_ON((unsigned long)pud & (PAGE_SIZE-1));
- free_page((unsigned long)pud);
+ pgtable_page_dec(page);
+ __free_page(page);
}

#ifndef __HAVE_ARCH_PUD_FREE
--
1.8.3.1