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

Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx> · Fri, 1 Jul 2022 16:04:21 +0800

On 6/30/2022 10:17 PM, Mike Rapoport wrote:
On Thu, Jun 30, 2022 at 07:11:15PM +0800, Baolin Wang wrote:
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@xxxxxxxxxxxxxxxxx>
---
  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);

Using pgtable_pud_page_ctor() and pgtable_pud_page_dtor() would be
consistent with what we currently have for PTEs and PMDs.

This applies to all the additions of pgtable_page_dec() and
pgtable_page_inc().

OK. I can add pgtable_pud_page_ctor() and pgtable_pud_page_dtor() 
helpers to keep consistent, which are just wrappers of 
pgtable_page_inc() and pgtable_page_dec().


+	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









