linux-kernel - Re: [PATCH] mm/debug_vm_pgtable: Add [pte|pmd]_mkwrite

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Message-ID: <875xc8ap0k.fsf@DESKTOP-5N7EMDA>
Date: Tue, 21 Oct 2025 11:54:03 +0800
From: "Huang, Ying" <ying.huang@...ux.alibaba.com>
To: Anshuman Khandual <anshuman.khandual@....com>
Cc: linux-mm@...ck.org,  Andrew Morton <akpm@...ux-foundation.org>,  David
 Hildenbrand <david@...hat.com>,  linux-kernel@...r.kernel.org,  Catalin
 Marinas <catalin.marinas@....com>
Subject: Re: [PATCH] mm/debug_vm_pgtable: Add [pte|pmd]_mkwrite_novma() tests

Anshuman Khandual <anshuman.khandual@....com> writes:

> Add some [pte|pmd]_mkwrite_novma() relevant tests.
>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: David Hildenbrand <david@...hat.com>
> Cc: Huang Ying <ying.huang@...ux.alibaba.com>
> Cc: linux-mm@...ck.org
> Cc: linux-kernel@...r.kernel.org
> Suggested-by: Catalin Marinas <catalin.marinas@....com>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
> ---
> These tests clear on arm64 platform after the following recent patch.
>
> https://lore.kernel.org/all/20251015023712.46598-1-ying.huang@linux.alibaba.com/
>
>  mm/debug_vm_pgtable.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> index 830107b6dd08..b9cae1580782 100644
> --- a/mm/debug_vm_pgtable.c
> +++ b/mm/debug_vm_pgtable.c
> @@ -102,6 +102,11 @@ static void __init pte_basic_tests(struct pgtable_debug_args *args, int idx)
>  	WARN_ON(pte_write(pte_wrprotect(pte_mkwrite(pte, args->vma))));
>  	WARN_ON(pte_dirty(pte_wrprotect(pte_mkclean(pte))));
>  	WARN_ON(!pte_dirty(pte_wrprotect(pte_mkdirty(pte))));
> +
> +	WARN_ON(pte_dirty(pte_mkwrite_novma(pte_mkclean(pte))));

Why not use: pte_mkwrite(pte, args->vma)?

Maybe add

        WARN_ON(!pte_dirty(pte_mkwrite_novma(pte_mkdirty(pte))));

> +	WARN_ON(!pte_write(pte_mkdirty(pte_mkwrite_novma(pte))));
> +	WARN_ON(!pte_write(pte_mkwrite_novma(pte_wrprotect(pte))));
> +	WARN_ON(pte_write(pte_wrprotect(pte_mkwrite_novma(pte))));
>  }
>  
>  static void __init pte_advanced_tests(struct pgtable_debug_args *args)
> @@ -195,6 +200,11 @@ static void __init pmd_basic_tests(struct pgtable_debug_args *args, int idx)
>  	WARN_ON(pmd_write(pmd_wrprotect(pmd_mkwrite(pmd, args->vma))));
>  	WARN_ON(pmd_dirty(pmd_wrprotect(pmd_mkclean(pmd))));
>  	WARN_ON(!pmd_dirty(pmd_wrprotect(pmd_mkdirty(pmd))));
> +
> +	WARN_ON(pmd_dirty(pmd_mkwrite_novma(pmd_mkclean(pmd))));
> +	WARN_ON(!pmd_write(pmd_mkdirty(pmd_mkwrite_novma(pmd))));
> +	WARN_ON(!pmd_write(pmd_mkwrite_novma(pmd_wrprotect(pmd))));
> +	WARN_ON(pmd_write(pmd_wrprotect(pmd_mkwrite_novma(pmd))));
>  	/*
>  	 * A huge page does not point to next level page table
>  	 * entry. Hence this must qualify as pmd_bad().

---
Best Regards,
Huang, Ying