linux-kernel - [RFC PATCH v2 3/3] mm: Add kernel PTE level pagetable pages account

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Date:   Wed, 22 Jun 2022 16:58:54 +0800
From:   Baolin Wang <baolin.wang@...ux.alibaba.com>
To:     akpm@...ux-foundation.org
Cc:     rppt@...ux.ibm.com, willy@...radead.org,
        baolin.wang@...ux.alibaba.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [RFC PATCH v2 3/3] mm: Add kernel PTE level pagetable pages account

Now the kernel PTE level ptes are always protected by mm->page_table_lock
instead of split pagetable lock, so the kernel PTE level pagetable pages
are not accounted. Especially the vmalloc()/vmap() can consume lots of
kernel pagetable, so to get an accurate pagetable accounting, calling new
helpers pgtable_set_and_inc()/pgtable_clear_and_dec() when allocating or
freeing a kernel PTE level pagetable page.

Meanwhile converting architectures to use corresponding generic PTE pagetable
allocation and freeing functions.

Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
Reported-by: kernel test robot <oliver.sang@...el.com>
---
 arch/csky/include/asm/pgalloc.h |  2 +-
 arch/microblaze/mm/pgtable.c    |  2 +-
 arch/openrisc/mm/ioremap.c      |  2 +-
 arch/x86/mm/pgtable.c           |  5 ++++-
 include/asm-generic/pgalloc.h   | 14 ++++++++++++--
 5 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/arch/csky/include/asm/pgalloc.h b/arch/csky/include/asm/pgalloc.h
index bbbd069..2443226 100644
--- a/arch/csky/include/asm/pgalloc.h
+++ b/arch/csky/include/asm/pgalloc.h
@@ -29,7 +29,7 @@ static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
 	pte_t *pte;
 	unsigned long i;
 
-	pte = (pte_t *) __get_free_page(GFP_KERNEL);
+	pte = __pte_alloc_one_kernel(mm);
 	if (!pte)
 		return NULL;
 
diff --git a/arch/microblaze/mm/pgtable.c b/arch/microblaze/mm/pgtable.c
index 9f73265..e96dd1b 100644
--- a/arch/microblaze/mm/pgtable.c
+++ b/arch/microblaze/mm/pgtable.c
@@ -245,7 +245,7 @@ unsigned long iopa(unsigned long addr)
 __ref pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
 {
 	if (mem_init_done)
-		return (pte_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
+		return __pte_alloc_one_kernel(mm);
 	else
 		return memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE,
 					      MEMBLOCK_LOW_LIMIT,
diff --git a/arch/openrisc/mm/ioremap.c b/arch/openrisc/mm/ioremap.c
index daae13a..3453acc 100644
--- a/arch/openrisc/mm/ioremap.c
+++ b/arch/openrisc/mm/ioremap.c
@@ -118,7 +118,7 @@ pte_t __ref *pte_alloc_one_kernel(struct mm_struct *mm)
 	pte_t *pte;
 
 	if (likely(mem_init_done)) {
-		pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
+		pte = __pte_alloc_one_kernel(mm);
 	} else {
 		pte = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
 		if (!pte)
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index a8ab3f9..fc2b9ef 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -851,6 +851,7 @@ int pud_free_pmd_page(pud_t *pud, unsigned long addr)
 int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
 {
 	pte_t *pte;
+	struct page *page;
 
 	pte = (pte_t *)pmd_page_vaddr(*pmd);
 	pmd_clear(pmd);
@@ -858,7 +859,9 @@ int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
 	/* INVLPG to clear all paging-structure caches */
 	flush_tlb_kernel_range(addr, addr + PAGE_SIZE-1);
 
-	free_page((unsigned long)pte);
+	page = virt_to_page(pte);
+	pgtable_clear_and_dec(page);
+	__free_page(page);
 
 	return 1;
 }
diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h
index 328a714..2e20e9e 100644
--- a/include/asm-generic/pgalloc.h
+++ b/include/asm-generic/pgalloc.h
@@ -18,7 +18,14 @@
  */
 static inline pte_t *__pte_alloc_one_kernel(struct mm_struct *mm)
 {
-	return (pte_t *)__get_free_page(GFP_PGTABLE_KERNEL);
+	struct page *page;
+	gfp_t gfp = GFP_PGTABLE_KERNEL;
+
+	page = alloc_pages(gfp & ~__GFP_HIGHMEM, 0);
+	if (!page)
+		return NULL;
+	pgtable_set_and_inc(page);
+	return (pte_t *)page_address(page);
 }
 
 #ifndef __HAVE_ARCH_PTE_ALLOC_ONE_KERNEL
@@ -41,7 +48,10 @@ static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
  */
 static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
 {
-	free_page((unsigned long)pte);
+	struct page *page = virt_to_page(pte);
+
+	pgtable_clear_and_dec(page);
+	__free_page(page);
 }
 
 /**
-- 
1.8.3.1