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

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Message-ID: <5face11f-2e04-4f28-b474-7c22a10d05e0@arm.com>
Date: Tue, 21 Oct 2025 13:18:20 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: "Huang, Ying" <ying.huang@...ux.alibaba.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



On 21/10/25 9:24 AM, Huang, Ying wrote:
> 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))));

Sure, will add the above test as well.
> 
>> +	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