From: "David Hildenbrand (Red Hat)" <david@kernel.org>
To: Alex Shi <seakeel@gmail.com>,
alexs@kernel.org, Madhavan Srinivasan <maddy@linux.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.com>,
Christophe Leroy <chleroy@kernel.org>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Sven Schnelle <svens@linux.ibm.com>,
"David S . Miller" <davem@davemloft.net>,
Andreas Larsson <andreas@gaisler.com>,
Andrew Morton <akpm@linux-foundation.org>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
"Liam R . Howlett" <Liam.Howlett@oracle.com>,
Vlastimil Babka <vbabka@suse.cz>, Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>, Zi Yan <ziy@nvidia.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
Nico Pache <npache@redhat.com>,
Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
Barry Song <baohua@kernel.org>, Lance Yang <lance.yang@linux.dev>,
Matthew Brost <matthew.brost@intel.com>,
Joshua Hahn <joshua.hahnjy@gmail.com>,
Rakie Kim <rakie.kim@sk.com>, Byungchul Park <byungchul@sk.com>,
Gregory Price <gourry@gourry.net>,
Ying Huang <ying.huang@linux.alibaba.com>,
Alistair Popple <apopple@nvidia.com>,
Thomas Huth <thuth@redhat.com>, Will Deacon <will@kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Magnus Lindholm <linmag7@gmail.com>,
linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org,
sparclinux@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC PATCH 1/2] mm/pgtable: use ptdesc for pmd_huge_pte
Date: Thu, 18 Dec 2025 11:01:59 +0100 [thread overview]
Message-ID: <ee42b057-b2d1-4a61-a6b0-39f81f78a918@kernel.org> (raw)
In-Reply-To: <52e2c1eb-67cf-41ee-9088-760fb6258153@gmail.com>
On 12/15/25 01:53, Alex Shi wrote:
>
>
> On 2025/12/14 14:55, alexs@kernel.org wrote:
>> From: Alex Shi<alexs@kernel.org>
>>
>> 'pmd_huge_pte' are pgtable variables, but used 'pgtable->lru'
>> instead of pgtable->pt_list in pgtable_trans_huge_deposit/withdraw
>> functions, That's a bit weird.
>>
>> So let's convert the pgtable_t to precise 'struct ptdesc *' for
>> ptdesc->pmd_huge_pte, and mm->pmd_huge_pte, then convert function
>> pgtable_trans_huge_deposit() to use correct ptdesc.
>>
>> This convertion works for most of arch, but failed on s390/sparc/powerpc
>> since they use 'pte_t *' as pgtable_t. Is there any suggestion for these
>> archs? If we could have a solution, we may remove the pgtable_t for other
>> archs.
>
> If s390/sparc/powerpc can't align pgtable_t with others, we have to keep
> the pgtable_t to bridge different types. But we could take step to
> change pgtable_t as 'struct ptdesc *' in other archs. That could
> simplify and clarify related code too, isn't it?
Not sure. s390 and friends squeeze multiple actual page tables into a
single page and that single page has a single ptdesc.
I was rather hoping that we can make the code more consistent by making
everybody just point at the start of the page table? (that is, make it
consistent for all, not use ptdesc for some and pte_t * for others)
--
Cheers
David
next prev parent reply other threads:[~2025-12-18 10:02 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-14 6:55 alexs
2025-12-14 6:55 ` [RFC PATCH 2/2] mm/pgtable: convert pgtable_trans_huge_withdraw to ptdesc alexs
2025-12-15 0:53 ` [RFC PATCH 1/2] mm/pgtable: use ptdesc for pmd_huge_pte Alex Shi
2025-12-18 10:01 ` David Hildenbrand (Red Hat) [this message]
2025-12-18 14:16 ` Alex Shi
2025-12-15 6:06 ` Christophe Leroy (CS GROUP)
2025-12-15 14:26 ` Alex Shi
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