From: Gavin Shan <gshan@redhat.com>
To: Anshuman Khandual <anshuman.khandual@arm.com>, linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org, catalin.marinas@arm.com,
will@kernel.org, akpm@linux-foundation.org, chuhu@redhat.com,
shan.gavin@gmail.com
Subject: Re: [PATCH v3 01/12] mm/debug_vm_pgtable: Introduce struct pgtable_debug_args
Date: Fri, 23 Jul 2021 10:43:20 +1000 [thread overview]
Message-ID: <118678e4-b67a-2141-8caa-3bbb9e9cdc19@redhat.com> (raw)
In-Reply-To: <4a534102-11ff-c849-781e-ed173e46da56@arm.com>
Hi Anshuman,
On 7/22/21 5:08 PM, Anshuman Khandual wrote:
> On 7/22/21 11:53 AM, Gavin Shan wrote:
>> On 7/22/21 2:41 PM, Anshuman Khandual wrote:
>>> On 7/21/21 3:50 PM, Gavin Shan wrote:
>>>> On 7/21/21 3:44 PM, Anshuman Khandual wrote:
>>>>> On 7/19/21 6:36 PM, Gavin Shan wrote:
>>>>>> In debug_vm_pgtable(), there are many local variables introduced to
>>>>>> track the needed information and they are passed to the functions for
>>>>>> various test cases. It'd better to introduce a struct as place holder
>>>>>> for these information. With it, what the functions for various test
>>>>>> cases need is the struct, to simplify the code. It also makes code
>>>>>> easier to be maintained.
>>>>>>
>>>>>> Besides, set_xxx_at() could access the data on the corresponding pages
>>>>>> in the page table modifying tests. So the accessed pages in the tests
>>>>>> should have been allocated from buddy. Otherwise, we're accessing pages
>>>>>> that aren't owned by us. This causes issues like page flag corruption.
>>>>>>
>>>>>> This introduces "struct pgtable_debug_args". The struct is initialized
>>>>>> and destroyed, but the information in the struct isn't used yet. They
>>>>>> will be used in subsequent patches.
>>>>>>
>>>>>> Signed-off-by: Gavin Shan <gshan@redhat.com>
>>>>>> ---
>>>>>> mm/debug_vm_pgtable.c | 197 +++++++++++++++++++++++++++++++++++++++++-
>>>>>> 1 file changed, 196 insertions(+), 1 deletion(-)
>>>>>>
[...]
>>>
>>> IIRC it is also not guaranteed that PMD_SHIFT <= (MAX_ORDER - 1). Hence
>>> this same scheme should be followed for PMD level allocation as well.
>>>
>>
>> In theory, it's possible to have PMD_SHIFT <= (MAX_ORDER - 1) with misconfigured
>> kernel. I will apply the similar logic to PMD huge page in v4.
>>
>>>> [... The code to release the PUD huge page needs changes based on @args->is_contiguous_pud_page]
>>>
>>> Right, a flag would be needed to call the appropriate free function.
>>>
>>
>> Yes. We need two falgs for PUD and PMD huge pages separately.
>
> A single flag should be enough, the order would be dependent on
> whether args->pud_pfn or args->pmd_pfn is valid.
>
Yes, it's correct that one flag is enough as we're sharing the PUD
or PMD huge page.
Thanks,
Gavin
next prev parent reply other threads:[~2021-07-23 0:44 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-19 13:06 [PATCH v3 00/12] mm/debug_vm_pgtable: Enhancements Gavin Shan
2021-07-19 13:06 ` [PATCH v3 01/12] mm/debug_vm_pgtable: Introduce struct pgtable_debug_args Gavin Shan
2021-07-21 5:44 ` Anshuman Khandual
2021-07-21 10:20 ` Gavin Shan
2021-07-21 10:39 ` Anshuman Khandual
2021-07-21 10:59 ` Anshuman Khandual
2021-07-21 11:59 ` Gavin Shan
2021-07-22 4:41 ` Anshuman Khandual
2021-07-22 6:23 ` Gavin Shan
2021-07-22 7:08 ` Anshuman Khandual
2021-07-23 0:43 ` Gavin Shan [this message]
2021-07-19 13:06 ` [PATCH v3 02/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in basic tests Gavin Shan
2021-07-21 5:57 ` Anshuman Khandual
2021-07-21 11:57 ` Gavin Shan
2021-07-19 13:06 ` [PATCH v3 03/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in leaf and savewrite tests Gavin Shan
2021-07-19 13:06 ` [PATCH v3 04/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in protnone and devmap tests Gavin Shan
2021-07-19 13:06 ` [PATCH v3 05/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in soft_dirty and swap tests Gavin Shan
2021-07-19 13:06 ` [PATCH v3 06/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in migration and thp tests Gavin Shan
2021-07-19 13:06 ` [PATCH v3 07/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in PTE modifying tests Gavin Shan
2021-07-22 5:56 ` Anshuman Khandual
2021-07-22 6:37 ` Gavin Shan
2021-07-23 2:39 ` Anshuman Khandual
2021-07-23 4:23 ` Gavin Shan
2021-07-19 13:06 ` [PATCH v3 08/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in PMD " Gavin Shan
2021-07-22 5:45 ` Anshuman Khandual
2021-07-22 6:41 ` Gavin Shan
2021-07-22 7:11 ` Anshuman Khandual
2021-07-23 1:00 ` Gavin Shan
2021-07-23 2:33 ` Anshuman Khandual
2021-07-19 13:06 ` [PATCH v3 09/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in PUD " Gavin Shan
2021-07-22 5:39 ` Anshuman Khandual
2021-07-22 6:47 ` Gavin Shan
2021-07-19 13:06 ` [PATCH v3 10/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in PGD and P4D " Gavin Shan
2021-07-22 5:09 ` Anshuman Khandual
2021-07-22 6:50 ` Gavin Shan
2021-07-19 13:06 ` [PATCH v3 11/12] mm/debug_vm_pgtable: Remove unused code Gavin Shan
2021-07-22 4:51 ` Anshuman Khandual
2021-07-22 6:53 ` Gavin Shan
2021-07-19 13:06 ` [PATCH v3 12/12] mm/debug_vm_pgtable: Fix corrupted page flag Gavin Shan
2021-07-21 10:18 ` Anshuman Khandual
2021-07-21 12:03 ` Gavin Shan
2021-07-22 3:51 ` Anshuman Khandual
2021-07-22 6:54 ` Gavin Shan
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