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Mon, 20 Jun 2022 03:25:11 -0700 (PDT) X-Gm-Message-State: AJIora8XTNiu8wQXtg2B6gozAQ97l4flDn/qj+VJW/VR+7FmVJbXN29T pSH0HEwyf34BnQk2gBWoGif+03sGTAJEeyiqmYo= X-Google-Smtp-Source: AGRyM1sXsuRv6jWKN7rLyi3u2sdEL6N9Z8dSCWko9wHPJ5B4Vut6/qbcY3PvEaHtIEqGwmVbYEiVgfPn4C94j2F9EKQ= X-Received: by 2002:a2e:95c8:0:b0:255:abb5:d0e7 with SMTP id y8-20020a2e95c8000000b00255abb5d0e7mr11071552ljh.23.1655720710073; Mon, 20 Jun 2022 03:25:10 -0700 (PDT) MIME-Version: 1.0 References: <20220617145859.582176-1-chenhuacai@loongson.cn> In-Reply-To: From: Huacai Chen Date: Mon, 20 Jun 2022 18:24:58 +0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] LoongArch: Add sparse memory vmemmap support To: Arnd Bergmann Cc: Huacai Chen , loongarch@lists.linux.dev, linux-arch , Xuefeng Li , Guo Ren , Xuerui Wang , Jiaxun Yang , Andrew Morton , Linux-MM , Min Zhou Content-Type: text/plain; charset="UTF-8" ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1655720715; a=rsa-sha256; cv=none; b=qkmSGNmXbd/Nx8pvgRtyPq3CDNj37SdpCfAv1fLvMnjrmSUFOco7YRqtciVyCxM/CR4UBy yFv+ds8IgIOtRDZ6821F5BtEeutsvfE6r5YSBsjDo9O2LvzOClJWNl/7KyR1zHYy27FuDi IbeYMFrnSTUFzRy/ASCukYJW4eBH2rU= ARC-Authentication-Results: i=1; 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spf=pass (imf06.hostedemail.com: domain of chenhuacai@kernel.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=chenhuacai@kernel.org X-Rspam-User: X-Stat-Signature: kq74gobestj19uytubzq5pafrhxc5hg3 X-Rspamd-Queue-Id: B5A271800A3 X-Rspamd-Server: rspam08 X-HE-Tag: 1655720715-748013 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: Hi, Arnd, On Fri, Jun 17, 2022 at 11:42 PM Arnd Bergmann wrote: > > On Fri, Jun 17, 2022 at 4:58 PM Huacai Chen wrote: > > > > Add sparse memory vmemmap support for LoongArch. SPARSEMEM_VMEMMAP > > uses a virtually mapped memmap to optimise pfn_to_page and page_to_pfn > > operations. This is the most efficient option when sufficient kernel > > resources are available. > > I have not looked at this in detail, but from a high-level perspective, it > seems very similar to the corresponding code in arch/arm64 and arch/x86. > > Can you try to merge the three copies into a generic helper and add that > to mm/sparse-vmemmap.c? If this does not work, can you describe in the > changelog text why these have to be architecture specific? It is difficult to merge, because LoongArch needs to call pud_init(), pmd_init() and other similar things which are unnecessary on ARM64 and X86. Huacai > > Arnd