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[149.14.88.26]) by smtp.gmail.com with ESMTPSA id jj2-20020a05600c6a0200b004126732390asm1837805wmb.37.2024.02.21.01.27.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 21 Feb 2024 01:27:10 -0800 (PST) Message-ID: Date: Wed, 21 Feb 2024 10:27:06 +0100 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/4] mm: pgalloc: support address-conditional pmd allocation Content-Language: en-US To: Christophe Leroy , Maxwell Bland , "linux-arm-kernel@lists.infradead.org" Cc: "gregkh@linuxfoundation.org" , "agordeev@linux.ibm.com" , "akpm@linux-foundation.org" , "andreyknvl@gmail.com" , "andrii@kernel.org" , "aneesh.kumar@kernel.org" , "aou@eecs.berkeley.edu" , "ardb@kernel.org" , "arnd@arndb.de" , "ast@kernel.org" , "borntraeger@linux.ibm.com" , "bpf@vger.kernel.org" , "brauner@kernel.org" , "catalin.marinas@arm.com" , "cl@linux.com" , "daniel@iogearbox.net" , "dave.hansen@linux.intel.com" , "dennis@kernel.org" , "dvyukov@google.com" , "glider@google.com" , "gor@linux.ibm.com" , "guoren@kernel.org" , "haoluo@google.com" , "hca@linux.ibm.com" , "hch@infradead.org" , "john.fastabend@gmail.com" , "jolsa@kernel.org" , "kasan-dev@googlegroups.com" , "kpsingh@kernel.org" , "linux-arch@vger.kernel.org" , "linux@armlinux.org.uk" , "linux-efi@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "linuxppc-dev@lists.ozlabs.org" , "linux-riscv@lists.infradead.org" , "linux-s390@vger.kernel.org" , "lstoakes@gmail.com" , "mark.rutland@arm.com" , "martin.lau@linux.dev" , "meted@linux.ibm.com" , "michael.christie@oracle.com" , "mjguzik@gmail.com" , "mpe@ellerman.id.au" , "mst@redhat.com" , "muchun.song@linux.dev" , "naveen.n.rao@linux.ibm.com" , "npiggin@gmail.com" , "palmer@dabbelt.com" , "paul.walmsley@sifive.com" , "quic_nprakash@quicinc.com" , "quic_pkondeti@quicinc.com" , "rick.p.edgecombe@intel.com" , "ryabinin.a.a@gmail.com" , "ryan.roberts@arm.com" , "samitolvanen@google.com" , "sdf@google.com" , "song@kernel.org" , "surenb@google.com" , "svens@linux.ibm.com" , "tj@kernel.org" , "urezki@gmail.com" , "vincenzo.frascino@arm.com" , "will@kernel.org" , "wuqiang.matt@bytedance.com" , "yonghong.song@linux.dev" , "zlim.lnx@gmail.com" , "awheeler@motorola.com" References: <20240220203256.31153-1-mbland@motorola.com> <20240220203256.31153-3-mbland@motorola.com> <838a05f0-568d-481d-b826-d2bb61908ace@csgroup.eu> From: David Hildenbrand Autocrypt: addr=david@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 21.02.24 08:13, Christophe Leroy wrote: > > > Le 20/02/2024 à 21:32, Maxwell Bland a écrit : >> [Vous ne recevez pas souvent de courriers de mbland@motorola.com. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ] >> >> While other descriptors (e.g. pud) allow allocations conditional on >> which virtual address is allocated, pmd descriptor allocations do not. >> However, adding support for this is straightforward and is beneficial to >> future kernel development targeting the PMD memory granularity. >> >> As many architectures already implement pmd_populate_kernel in an >> address-generic manner, it is necessary to roll out support >> incrementally. For this purpose a preprocessor flag, > > Is it really worth it ? It is only 48 call sites that need to be > updated. It would avoid that processor flag and avoid introducing that > pmd_populate_kernel_at() in kernel core. +1, let's avoid that if possible. -- Cheers, David / dhildenb