linux-kernel - Re: [PATCH v3 1/2] mm: add per-order mTHP split counters

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Message-ID: <3aef2bc6-c889-4a9a-b35d-f10ca8a5796a@redhat.com>
Date: Fri, 5 Jul 2024 12:14:16 +0200
From: David Hildenbrand <david@...hat.com>
To: Barry Song <21cnbao@...il.com>
Cc: Lance Yang <ioworker0@...il.com>, akpm@...ux-foundation.org,
 dj456119@...il.com, ryan.roberts@....com, shy828301@...il.com,
 ziy@...dia.com, libang.li@...group.com, baolin.wang@...ux.alibaba.com,
 linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 Mingzhe Yang <mingzhe.yang@...com>
Subject: Re: [PATCH v3 1/2] mm: add per-order mTHP split counters

On 05.07.24 12:12, Barry Song wrote:
> On Fri, Jul 5, 2024 at 9:08 PM David Hildenbrand <david@...hat.com> wrote:
>>
>>> @@ -3253,8 +3259,9 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
>>>                i_mmap_unlock_read(mapping);
>>>    out:
>>>        xas_destroy(&xas);
>>> -     if (is_thp)
>>> +     if (order >= HPAGE_PMD_ORDER)
>>
>> We likely should be using "== HPAGE_PMD_ORDER" here, to be safe for the
>> future.
> 
> I feel this might need to be separate since all other places are using
> folio_test_pmd_mappable() ?

Likely, but as you are moving away from this ... this counter here does 
and will always only care about HPAGE_PMD_ORDER.

-- 
Cheers,

David / dhildenb