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From:   Jonathan Corbet <corbet@lwn.net>
To:     Mike Rapoport <rppt@kernel.org>,
        Usama Arif <usama.arif@bytedance.com>
Cc:     songmuchun@bytedance.com, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
        fam.zheng@bytedance.com, liangma@liangbit.com
Subject: Re: [External] Re: [PATCH] docs: mm: Fix number of base pages for
 1GB HugeTLB
In-Reply-To: <ZL9msij+DaXiDHbq@kernel.org>
References: <20230207114456.2304801-1-usama.arif@bytedance.com>
 <Y+NwkCsDnOBSCqVu@kernel.org>
 <463c960e-1d3b-edc0-edbb-d5ecbf7fc3b1@bytedance.com>
 <ZL9msij+DaXiDHbq@kernel.org>
Date:   Mon, 31 Jul 2023 10:03:42 -0600
Message-ID: <87bkfsdq5d.fsf@meer.lwn.net>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

Mike Rapoport <rppt@kernel.org> writes:

> (adding Jon)
>
> On Mon, Jul 24, 2023 at 03:05:29PM +0100, Usama Arif wrote:
>> 
>> 
>> On 08/02/2023 09:51, Mike Rapoport wrote:
>> > On Tue, Feb 07, 2023 at 11:44:56AM +0000, Usama Arif wrote:
>> > > 1GB HugeTLB page consists of 262144 base pages.
>> > > 
>> > > Signed-off-by: Usama Arif <usama.arif@bytedance.com>
>> > 
>> > Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
>> > 
>> > > ---
>> > >   Documentation/mm/vmemmap_dedup.rst | 3 ++-
>> > >   1 file changed, 2 insertions(+), 1 deletion(-)
>> > > 
>> > > diff --git a/Documentation/mm/vmemmap_dedup.rst b/Documentation/mm/vmemmap_dedup.rst
>> > > index a4b12ff906c4..689a6907c70b 100644
>> > > --- a/Documentation/mm/vmemmap_dedup.rst
>> > > +++ b/Documentation/mm/vmemmap_dedup.rst
>> > > @@ -1,3 +1,4 @@
>> > > +
>> > >   .. SPDX-License-Identifier: GPL-2.0
>> > >   =========================================
>> > > @@ -17,7 +18,7 @@ HugeTLB pages consist of multiple base page size pages and is supported by many
>> > >   architectures. See Documentation/admin-guide/mm/hugetlbpage.rst for more
>> > >   details. On the x86-64 architecture, HugeTLB pages of size 2MB and 1GB are
>> > >   currently supported. Since the base page size on x86 is 4KB, a 2MB HugeTLB page
>> > > -consists of 512 base pages and a 1GB HugeTLB page consists of 4096 base pages.
>> > > +consists of 512 base pages and a 1GB HugeTLB page consists of 262144 base pages.
>> > >   For each base page, there is a corresponding ``struct page``.
>> > >   Within the HugeTLB subsystem, only the first 4 ``struct page`` are used to
>> > > -- 
>> > > 2.25.1
>> > > 
>> > 
>> 
>> Hi,
>> 
>> Was just reading vmemmap_dedup.rst for something and realized that its still
>> 4096 pages for 1G, maybe this patch got missed?

Dug out of the archives and applied, thanks.

jon