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From: Anshuman Khandual <anshuman.khandual@arm.com>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
	linux-mm@kvack.org, akpm@linux-foundation.org
Cc: linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v4 11/13] mm/debug_vm_pgtable/pmd_clear: Don't use pmd/pud_clear on pte entries
Date: Fri, 4 Sep 2020 11:33:04 +0530
Message-ID: <8251b4b6-63ee-cbf8-63dd-c0031a010a4b@arm.com> (raw)
In-Reply-To: <20200902114222.181353-12-aneesh.kumar@linux.ibm.com>



On 09/02/2020 05:12 PM, Aneesh Kumar K.V wrote:
> pmd_clear() should not be used to clear pmd level pte entries.
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> ---
>  mm/debug_vm_pgtable.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> index 26023d990bd0..b53903fdee85 100644
> --- a/mm/debug_vm_pgtable.c
> +++ b/mm/debug_vm_pgtable.c
> @@ -196,6 +196,8 @@ static void __init pmd_advanced_tests(struct mm_struct *mm,
>  	pmd = READ_ONCE(*pmdp);
>  	WARN_ON(pmd_young(pmd));
>  
> +	/*  Clear the pte entries  */
> +	pmdp_huge_get_and_clear(mm, vaddr, pmdp);
>  	pgtable = pgtable_trans_huge_withdraw(mm, pmdp);
>  }
>  
> @@ -319,6 +321,8 @@ static void __init pud_advanced_tests(struct mm_struct *mm,
>  	pudp_test_and_clear_young(vma, vaddr, pudp);
>  	pud = READ_ONCE(*pudp);
>  	WARN_ON(pud_young(pud));
> +
> +	pudp_huge_get_and_clear(mm, vaddr, pudp);
>  }
>  
>  static void __init pud_leaf_tests(unsigned long pfn, pgprot_t prot)
> @@ -442,8 +446,6 @@ static void __init pud_populate_tests(struct mm_struct *mm, pud_t *pudp,
>  	 * This entry points to next level page table page.
>  	 * Hence this must not qualify as pud_bad().
>  	 */
> -	pmd_clear(pmdp);
> -	pud_clear(pudp);
>  	pud_populate(mm, pudp, pmdp);
>  	pud = READ_ONCE(*pudp);
>  	WARN_ON(pud_bad(pud));
> @@ -575,7 +577,6 @@ static void __init pmd_populate_tests(struct mm_struct *mm, pmd_t *pmdp,
>  	 * This entry points to next level page table page.
>  	 * Hence this must not qualify as pmd_bad().
>  	 */
> -	pmd_clear(pmdp);
>  	pmd_populate(mm, pmdp, pgtable);
>  	pmd = READ_ONCE(*pmdp);
>  	WARN_ON(pmd_bad(pmd));
> 

Why pxxp_huge_get_and_clear() cannot be called inside pxx_populate_tests()
functions itself ? Nonetheless, this does not seem to cause any problem.

  reply index

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-02 11:42 [PATCH v4 00/13] mm/debug_vm_pgtable fixes Aneesh Kumar K.V
2020-09-02 11:42 ` [PATCH v4 01/13] powerpc/mm: Add DEBUG_VM WARN for pmd_clear Aneesh Kumar K.V
2020-09-02 11:42 ` [PATCH v4 02/13] powerpc/mm: Move setting pte specific flags to pfn_pte Aneesh Kumar K.V
2020-09-02 12:30   ` Christophe Leroy
2020-09-02 11:42 ` [PATCH v4 03/13] mm/debug_vm_pgtable/ppc64: Avoid setting top bits in radom value Aneesh Kumar K.V
2020-09-04  4:03   ` Anshuman Khandual
2020-09-02 11:42 ` [PATCH v4 04/13] mm/debug_vm_pgtables/hugevmap: Use the arch helper to identify huge vmap support Aneesh Kumar K.V
2020-09-02 12:40   ` Christophe Leroy
2020-09-02 12:53     ` Aneesh Kumar K.V
2020-09-04  4:08   ` Anshuman Khandual
2020-09-02 11:42 ` [PATCH v4 05/13] mm/debug_vm_pgtable/savedwrite: Enable savedwrite test with CONFIG_NUMA_BALANCING Aneesh Kumar K.V
2020-09-04  4:09   ` Anshuman Khandual
2020-09-02 11:42 ` [PATCH v4 06/13] mm/debug_vm_pgtable/THP: Mark the pte entry huge before using set_pmd/pud_at Aneesh Kumar K.V
2020-09-04  5:21   ` Anshuman Khandual
2020-09-02 11:42 ` [PATCH v4 07/13] mm/debug_vm_pgtable/set_pte/pmd/pud: Don't use set_*_at to update an existing pte entry Aneesh Kumar K.V
2020-09-04  5:34   ` Anshuman Khandual
2020-09-02 11:42 ` [PATCH v4 08/13] mm/debug_vm_pgtable/locks: Move non page table modifying test together Aneesh Kumar K.V
2020-09-04  3:58   ` Anshuman Khandual
2020-09-02 11:42 ` [PATCH v4 09/13] mm/debug_vm_pgtable/locks: Take correct page table lock Aneesh Kumar K.V
2020-09-04  5:39   ` Anshuman Khandual
2020-09-02 11:42 ` [PATCH v4 10/13] mm/debug_vm_pgtable/thp: Use page table depost/withdraw with THP Aneesh Kumar K.V
2020-09-04  4:21   ` Anshuman Khandual
2020-09-02 11:42 ` [PATCH v4 11/13] mm/debug_vm_pgtable/pmd_clear: Don't use pmd/pud_clear on pte entries Aneesh Kumar K.V
2020-09-04  6:03   ` Anshuman Khandual [this message]
2020-09-02 11:42 ` [PATCH v4 12/13] mm/debug_vm_pgtable/hugetlb: Disable hugetlb test on ppc64 Aneesh Kumar K.V
2020-09-04  6:19   ` Anshuman Khandual
2020-09-02 11:42 ` [PATCH v4 13/13] mm/debug_vm_pgtable: Avoid none pte in pte_clear_test Aneesh Kumar K.V
2020-09-11  2:13   ` Nathan Chancellor
2020-09-11  5:21     ` Aneesh Kumar K.V
2020-09-23  3:14       ` Anshuman Khandual
2020-10-11 20:02   ` Guenter Roeck
2020-10-12  4:29     ` Aneesh Kumar K.V
2020-09-02 11:46 ` Aneesh Kumar K.V
2020-09-04  4:16   ` Anshuman Khandual
2020-09-04  6:48 ` [PATCH v4 00/13] mm/debug_vm_pgtable fixes Anshuman Khandual
2020-09-04 15:26   ` Gerald Schaefer
2020-09-04 16:01     ` Gerald Schaefer
2020-09-04 17:53       ` Gerald Schaefer
2020-09-09  8:38         ` Anshuman Khandual
2020-09-08 15:39       ` Gerald Schaefer
2020-09-09  6:08         ` Aneesh Kumar K.V
2020-09-09 11:16           ` Gerald Schaefer
2020-09-09  8:15       ` Anshuman Khandual
2020-09-09 11:10         ` Gerald Schaefer
2020-09-09  8:08     ` Anshuman Khandual
2020-09-09 11:36       ` Gerald Schaefer
2020-09-13 11:03 ` [PATCH] mm/debug_vm_pgtable: Avoid doing memory allocation with pgtable_t mapped Aneesh Kumar K.V
2020-09-13 13:42   ` Matthew Wilcox
2020-10-13 20:58 ` [PATCH v4 00/13] mm/debug_vm_pgtable fixes Andrew Morton
2020-10-14  3:15   ` Aneesh Kumar K.V
2020-10-14 20:36     ` Andrew Morton
2020-10-15  2:59       ` Anshuman Khandual

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