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

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Message-ID: <3269e0a6-29a4-478b-842a-629efc8d5d59@redhat.com>
Date: Fri, 15 Nov 2024 14:35:24 +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 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.

-- 
Cheers,

David / dhildenb