Re: [RFC PATCH 1/5] mm: memcg: make memcg huge page split support any order split.

From: Zi Yan <ziy@nvidia.com>
To: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Matthew Wilcox <willy@infradead.org>,
	linux-mm@kvack.org, Shuah Khan <shuah@kernel.org>,
	Yang Shi <shy828301@gmail.com>, Miaohe Lin <linmiaohe@huawei.com>,
	Hugh Dickins <hughd@google.com>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
	linux-kselftest@vger.kernel.org
Subject: Re: [RFC PATCH 1/5] mm: memcg: make memcg huge page split support any order split.
Date: Mon, 21 Mar 2022 15:07:46 -0400	[thread overview]
Message-ID: <0001CABA-9436-4EFF-9C7F-F67300D09DA1@nvidia.com> (raw)
In-Reply-To: <YjjKh2NoWGcq28Oo@carbon.dhcp.thefacebook.com>

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On 21 Mar 2022, at 14:57, Roman Gushchin wrote:

> On Mon, Mar 21, 2022 at 10:21:24AM -0400, Zi Yan wrote:
>> From: Zi Yan <ziy@nvidia.com>
>>
>> It sets memcg information for the pages after the split. A new parameter
>> new_order is added to tell the new page order, always 0 for now. It
>> prepares for upcoming changes to support split huge page to any lower
>> order.
>>
>> Signed-off-by: Zi Yan <ziy@nvidia.com>
>> ---
>>  include/linux/memcontrol.h |  2 +-
>>  mm/huge_memory.c           |  2 +-
>>  mm/memcontrol.c            | 10 +++++-----
>>  mm/page_alloc.c            |  2 +-
>>  4 files changed, 8 insertions(+), 8 deletions(-)
>>
>> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
>> index 89b14729d59f..e71189454bf0 100644
>> --- a/include/linux/memcontrol.h
>> +++ b/include/linux/memcontrol.h
>> @@ -1116,7 +1116,7 @@ static inline void memcg_memory_event_mm(struct mm_struct *mm,
>>  	rcu_read_unlock();
>>  }
>>
>> -void split_page_memcg(struct page *head, unsigned int nr);
>> +void split_page_memcg(struct page *head, unsigned int nr, unsigned int new_order);
>
> It looks a bit inconsistent, can't we switch to use either nr or order for both
> arguments? The latter is preferable.

Yes. Will change it to new_nr to be consistent.

>
> Other than that, the patch looks good to me.

Thank you for the review.

--
Best Regards,
Yan, Zi

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