From: Alex Shi <seakeel@gmail.com>
To: Matthew Wilcox <willy@infradead.org>, alexs@kernel.org
Cc: Will Deacon <will@kernel.org>,
"Aneesh Kumar K . V" <aneesh.kumar@kernel.org>,
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Subject: Re: [RFC PATCH 00/18] use struct ptdesc to replace pgtable_t
Date: Thu, 15 Aug 2024 14:17:45 +0800 [thread overview]
Message-ID: <02d7b8a2-b0d6-4713-b03e-5b22968387c3@gmail.com> (raw)
In-Reply-To: <ZrzlnIWrnaUx66rY@casper.infradead.org>
On 8/15/24 1:13 AM, Matthew Wilcox wrote:
> On Tue, Jul 30, 2024 at 02:46:54PM +0800, alexs@kernel.org wrote:
>> We have struct ptdesc for page table descriptor a year ago, but it
>> has no much usages in kernel, while pgtable_t is used widely.
>
> Hum, I thought I responded to this to point out the problem, but
> I don't see the response anywhere, so I'll try again.
>
>> The pgtable_t is typedefed as 'pte_t *' in sparc, s390, powerpc and m68k
>> except SUN3, others archs are all same as 'struct page *'.
>
> And there's a very good reason for that. On s390 and powerpc (I cannot
> speak to the sparc/m68k), each page table is (potentially) smaller
> than PAGE_SIZE. So we cannot do what your patch purports to do, as
> we would not know whether we're referring to the first or subsequent
> page tables contained within a page.
>> Maybe at some point in the distant future we'll be able to allocate
> a ptdesc per page table instead of per page allocated for use by page
> tables. But we cannot do that yet.
Got it. Thanks a lot for the info!
prev parent reply other threads:[~2024-08-15 6:17 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-30 6:46 [RFC PATCH 00/18] use struct ptdesc to replace pgtable_t alexs
2024-07-30 6:46 ` [RFC PATCH 01/18] mm/pgtable: use ptdesc in pte_free_now/pte_free_defer alexs
2024-07-30 6:46 ` [RFC PATCH 02/18] mm/pgtable: convert ptdesc.pmd_huge_pte to ptdesc pointer alexs
2024-07-30 6:46 ` [RFC PATCH 03/18] fs/dax: use ptdesc in dax_pmd_load_hole alexs
2024-07-30 6:46 ` [RFC PATCH 04/18] mm/thp: use ptdesc pointer in __do_huge_pmd_anonymous_page alexs
2024-07-30 6:46 ` [RFC PATCH 05/18] mm/thp: use ptdesc in do_huge_pmd_anonymous_page alexs
2024-07-30 6:47 ` [RFC PATCH 06/18] mm/thp: convert insert_pfn_pmd and its caller to use ptdesc alexs
2024-07-30 6:47 ` [RFC PATCH 07/18] mm/thp: use ptdesc in copy_huge_pmd alexs
2024-07-30 6:47 ` [RFC PATCH 08/18] mm/memory: use ptdesc in __pte_alloc alexs
2024-07-30 6:47 ` [RFC PATCH 09/18] mm/pgtable: fully use ptdesc in pte_alloc_one series functions alexs
2024-07-30 6:47 ` [RFC PATCH 10/18] mm/pgtable: pass ptdesc to pte_free() alexs
2024-07-30 7:27 ` [RFC PATCH 11/18] mm/pgtable: introduce ptdesc_pfn and use ptdesc in free_pte_range() alexs
2024-07-30 7:27 ` [RFC PATCH 12/18] mm/thp: pass ptdesc to set_huge_zero_folio function alexs
2024-07-30 7:27 ` [RFC PATCH 13/18] mm/pgtable: return ptdesc pointer in pgtable_trans_huge_withdraw alexs
2024-07-30 7:27 ` [RFC PATCH 14/18] mm/pgtable: use ptdesc in pgtable_trans_huge_deposit alexs
2024-07-30 7:27 ` [RFC PATCH 15/18] mm/pgtable: pass ptdesc to pmd_populate alexs
2024-07-30 7:27 ` [RFC PATCH 16/18] mm/pgtable: pass ptdesc to pmd_install alexs
2024-07-30 7:27 ` [RFC PATCH 17/18] mm: convert vmf.prealloc_pte to struct ptdesc pointer alexs
2024-07-30 7:27 ` [RFC PATCH 18/18] mm/pgtable: pass ptdesc in pte_free_defer alexs
2024-07-30 8:10 ` [RFC PATCH 00/18] use struct ptdesc to replace pgtable_t Alex Shi
2024-08-14 16:50 ` LEROY Christophe
2024-08-15 6:32 ` Alex Shi
2024-08-14 17:13 ` Matthew Wilcox
2024-08-15 6:17 ` Alex Shi [this message]
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