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(p200300cbc741de00bf0fcd46dc1c2de9.dip0.t-ipconnect.de. [2003:cb:c741:de00:bf0f:cd46:dc1c:2de9]) by smtp.gmail.com with ESMTPSA id v21-20020a05600c445500b0040e3bdff98asm45737522wmn.23.2024.01.23.03.53.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 23 Jan 2024 03:53:09 -0800 (PST) Message-ID: <1facdace-241a-4ceb-a206-bd44ea4e3ae4@redhat.com> Date: Tue, 23 Jan 2024 12:53:07 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 01/11] arm/pgtable: define PFN_PTE_SHIFT on arm and arm64 To: Christophe Leroy , Ryan Roberts , "linux-kernel@vger.kernel.org" Cc: "linux-mm@kvack.org" , Andrew Morton , Matthew Wilcox , Russell King , Catalin Marinas , Will Deacon , Dinh Nguyen , Michael Ellerman , Nicholas Piggin , "Aneesh Kumar K.V" , "Naveen N. Rao" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , "David S. Miller" , "linux-arm-kernel@lists.infradead.org" , "linuxppc-dev@lists.ozlabs.org" , "linux-riscv@lists.infradead.org" , "linux-s390@vger.kernel.org" , "sparclinux@vger.kernel.org" References: <20240122194200.381241-1-david@redhat.com> <20240122194200.381241-2-david@redhat.com> <46080ac1-7789-499b-b7f3-0231d7bd6de7@redhat.com> <6703b648-10ab-4fea-b7f1-75421319465b@arm.com> <3a970289-a72f-418e-b43c-89f67f0d5283@redhat.com> <11a7232c-8623-4c2c-b980-a13645f3fe89@csgroup.eu> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <11a7232c-8623-4c2c-b980-a13645f3fe89@csgroup.eu> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 6CD841C0005 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: agkwm6f389ciyengqkzbmq9gpjubpoed X-HE-Tag: 1706010793-397109 X-HE-Meta: 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 DC5TlRja 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 23.01.24 12:48, Christophe Leroy wrote: > > > Le 23/01/2024 à 12:38, Ryan Roberts a écrit : >> On 23/01/2024 11:31, David Hildenbrand wrote: >>>>> >>>>>> If high bits are used for >>>>>> something else, then we might produce a garbage PTE on overflow, but that >>>>>> shouldn't really matter I concluded for folio_pte_batch() purposes, we'd not >>>>>> detect "belongs to this folio batch" either way. >>>>> >>>>> Exactly. >>>>> >>>>>> >>>>>> Maybe it's likely cleaner to also have a custom pte_next_pfn() on ppc, I just >>>>>> hope that we don't lose any other arbitrary PTE bits by doing the pte_pgprot(). >>>>> >>>>> I don't see the need for ppc to implement pte_next_pfn(). >>>> >>>> Agreed. >>> >>> So likely we should then do on top for powerpc (whitespace damage): >>> >>> diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c >>> index a04ae4449a025..549a440ed7f65 100644 >>> --- a/arch/powerpc/mm/pgtable.c >>> +++ b/arch/powerpc/mm/pgtable.c >>> @@ -220,10 +220,7 @@ void set_ptes(struct mm_struct *mm, unsigned long addr, >>> pte_t *ptep, >>>                         break; >>>                 ptep++; >>>                 addr += PAGE_SIZE; >>> -               /* >>> -                * increment the pfn. >>> -                */ >>> -               pte = pfn_pte(pte_pfn(pte) + 1, pte_pgprot((pte))); >>> +               pte = pte_next_pfn(pte); >>>         } >>>  } >> >> Looks like commit 47b8def9358c ("powerpc/mm: Avoid calling >> arch_enter/leave_lazy_mmu() in set_ptes") changed from doing the simple >> increment to this more complex approach, but the log doesn't say why. > > Right. There was a discussion about it without any conclusion: > https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20231024143604.16749-1-aneesh.kumar@linux.ibm.com/ > > As far as understand the simple increment is better on ppc/32 but worse > in ppc/64. Sounds like we're micro-optimizing for a specific compiler version output. Hurray. -- Cheers, David / dhildenb