linux-kernel - Re: [PATCH v2 0/5] Support large folios for tmpfs

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Message-ID: <0387fb65-7c90-4766-9b9b-a4fb77709837@redhat.com>
Date: Fri, 15 Nov 2024 16:44:28 +0100
From: David Hildenbrand <david@...hat.com>
To: Daniel Gomez <da.gomez@...sung.com>,
 Baolin Wang <baolin.wang@...ux.alibaba.com>, akpm@...ux-foundation.org,
 hughd@...gle.com
Cc: willy@...radead.org, wangkefeng.wang@...wei.com, 21cnbao@...il.com,
 ryan.roberts@....com, ioworker0@...il.com, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/5] Support large folios for tmpfs

On 15.11.24 16:35, Daniel Gomez wrote:
> On Fri Nov 15, 2024 at 2:35 PM CET, David Hildenbrand wrote:
>> On 15.11.24 14:16, Daniel Gomez wrote:
>>> On Tue Nov 12, 2024 at 8:45 AM CET, Baolin Wang wrote:
>>>> Traditionally, tmpfs only supported PMD-sized huge folios. However nowadays
>>>
>>> Nitpick:
>>> We are mixing here folios/page, PMD-size huge. For anyone not aware of
>>> Memory Folios conversion in the kernel I think this makes it confusing.
>>> Tmpfs has never supported folios so, this is not true. Can we rephrase
>>> it?
>>
>> We had the exact same discussion when we added mTHP support to anonymous
>> memory.
>>
>> I suggest you read:
>>
>> https://lkml.kernel.org/r/65dbdf2a-9281-a3c3-b7e3-a79c5b60b357@redhat.com
>>
>> Folios are an implementation detail on how we manage metadata. Nobody in
>> user space should even have to be aware of how we manage metadata for
>> larger chunks of memory ("huge pages") in the kernel.
> 
> I read it and I can't find where the use of "PMD-size huge folios" could
> be a valid term. Tmpfs has never supported "folios", so I think using
> "PMD-size huge pages" is more appropiate.

Oh sorry, I completely agree. Yes, we should use that.

-- 
Cheers,

David / dhildenb