From: Wei Yang <richard.weiyang@gmail.com>
To: "Christophe Leroy (CS GROUP)" <chleroy@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>,
akpm@linux-foundation.org, david@kernel.org,
lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com,
vbabka@suse.cz, rppt@kernel.org, surenb@google.com,
mhocko@suse.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com,
npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com,
baohua@kernel.org, lance.yang@linux.dev, linux-mm@kvack.org
Subject: Re: [PATCH] mm: use standard page table accessors
Date: Wed, 26 Nov 2025 10:03:30 +0000 [thread overview]
Message-ID: <20251126100330.n66n3uvt3junflao@master> (raw)
In-Reply-To: <9c32675d-c48d-405f-a38f-4c90a8edac74@kernel.org>
On Wed, Nov 26, 2025 at 09:15:24AM +0100, Christophe Leroy (CS GROUP) wrote:
>
>
>Le 26/11/2025 à 07:47, Wei Yang a écrit :
>> Use standard page table accessors i.e pxdp_get() to get the value of
>> pxdp.
>
>Please provide more detail of why you want to do that and how you are sure it
>doesn't break existing implementation.
>
>There was similar tentative in the past already which proved to give
>suboptimal results, see discussion here:
>
>https://lore.kernel.org/all/f40ea8bf-0862-41a7-af19-70bfbd838568@csgroup.eu/
Interesting.
The reason is P4D/PUD/PMD on PPC32 actually just has PGD/PMD. So it is not
necessary to retrieve P4D and PUD.
If this is the case, sounds other platform with less pagetable level would be
affected too.
And this looks only affect when we walk the pagetable from pgd. If we just
iterating pmd/pte, we won't have this issue, right?
>
>Christophe
--
Wei Yang
Help you, Help me
next prev parent reply other threads:[~2025-11-26 10:03 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-26 6:47 Wei Yang
2025-11-26 8:15 ` Christophe Leroy (CS GROUP)
2025-11-26 10:03 ` Wei Yang [this message]
2025-11-26 10:28 ` Christophe Leroy (CS GROUP)
2025-11-26 12:15 ` Wei Yang
2025-11-26 9:09 ` David Hildenbrand (Red Hat)
2025-11-26 9:42 ` Wei Yang
2025-11-26 10:19 ` Ryan Roberts
2025-11-26 11:32 ` Ryan Roberts
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