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

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On 6/22/2022 10:44 PM, Mike Rapoport wrote:
On Wed, Jun 22, 2022 at 04:58:54PM +0800, Baolin Wang wrote:
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.

This patch only adds accounting to the page tables allocated after boot,
please mention this in the changelog.

OK. Will add in next version.

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

Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
---
  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);

{
	pte_t *pte = (pte_t *)__get_free_page(GFP_PGTABLE_KERNEL);

	if (pte)
		pgtable_set_and_inc(virt_to_page(pte));

	return pte;
}

looks simpler, doesn't it?

Yes, will do in next version. Thanks for reviewing.




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