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AJvYcCXG1MbWV6JxNpn3/2FVn49ZcxjonslENESRwIW1j9uRUKRJSznEKXgc3QpaCVtL/nMcgOez7q9RtbBF+9PPR6gbbUc= X-Gm-Message-State: AOJu0YzqZjlJE6ulCBnOZ6A2UCIQMko9yEhEs4hvonEB7L9eqrFyvUZr IJg1byqVb8PuGKn9U10D6tLqumPuwRvk7LVqD2TZQhHuWa3THulKNctqS/vAKpgLfeR/mQGPK/h TscRCngnO1tuGglKxbX7t477BoFnE7lcvG3QPtw== X-Google-Smtp-Source: AGHT+IFn+h3r/AaoF4MfmIEWnQLUDUmnx1Kec57gXxwxEXHIeMLPIowE5fZkN66KK2rAD8UQkIaND2e8M33sIsMCnhQ= X-Received: by 2002:a05:622a:1048:b0:42c:798a:a053 with SMTP id f8-20020a05622a104800b0042c798aa053mr4373943qte.55.1708045591818; Thu, 15 Feb 2024 17:06:31 -0800 (PST) MIME-Version: 1.0 References: <20240207174102.1486130-1-pasha.tatashin@soleen.com> <20240207174102.1486130-2-pasha.tatashin@soleen.com> <8ce2cd7b-7702-45aa-b4c8-25a01c27ed83@arm.com> In-Reply-To: From: Pasha Tatashin Date: Thu, 15 Feb 2024 20:05:55 -0500 Message-ID: Subject: Re: [PATCH v4 01/10] iommu/vt-d: add wrapper functions for page allocations To: Robin Murphy Cc: akpm@linux-foundation.org, alim.akhtar@samsung.com, alyssa@rosenzweig.io, asahi@lists.linux.dev, baolu.lu@linux.intel.com, bhelgaas@google.com, cgroups@vger.kernel.org, corbet@lwn.net, david@redhat.com, dwmw2@infradead.org, hannes@cmpxchg.org, heiko@sntech.de, iommu@lists.linux.dev, jernej.skrabec@gmail.com, jonathanh@nvidia.com, joro@8bytes.org, krzysztof.kozlowski@linaro.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-rockchip@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-sunxi@lists.linux.dev, linux-tegra@vger.kernel.org, lizefan.x@bytedance.com, marcan@marcan.st, mhiramat@kernel.org, m.szyprowski@samsung.com, paulmck@kernel.org, rdunlap@infradead.org, samuel@sholland.org, suravee.suthikulpanit@amd.com, sven@svenpeter.dev, thierry.reding@gmail.com, tj@kernel.org, tomas.mudrunka@gmail.com, vdumpa@nvidia.com, wens@csie.org, will@kernel.org, yu-cheng.yu@intel.com, rientjes@google.com, bagasdotme@gmail.com, mkoutny@suse.com Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: C9DC82001F X-Stat-Signature: kqo1qqjgk5p9qhjicyq1trhnd74xaa1g X-HE-Tag: 1708045592-839387 X-HE-Meta: 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 DFqCUSNz 9j51+1ojO6n1+cqfVnlZSV77rjOO+FVHRM7LHNADLRMpc6SHuSZ4uAKfxVdlOQ4Q0e9YZBSp2xdhaekWLBBK4xFb9mt7e7ZxSW/49p1vhuGl1E28h+dx77jC3pLMAVGrcV4NX 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: > >>> + */ > >>> +static inline void *iommu_alloc_page_node(int nid, gfp_t gfp) > >>> +{ > >>> + return iommu_alloc_pages_node(nid, gfp, 0); > >>> +} > >> > >> TBH I'm not entirely convinced that saving 4 characters per invocation > >> times 11 invocations makes this wrapper worthwhile :/ > > > > Let's keep them. After the clean-up that you suggested, there are > > fewer functions left in this file, but I think that it is cleaner to > > keep these remaining, as it is beneficial to easily distinguish when > > exactly one page is allocated vs when multiple are allocated via code > > search. > > But is it, really? It's not at all obvious to me *why* it would be > significantly interesting to distinguish fixed order-0 allocations from > higher-order or variable-order (which may still be 0) ones. After all, > there's no regular alloc_page_node() wrapper, yet plenty more callers of > alloc_pages_node(..., 0) :/ The pages that are allocated with order > 0 cannot be freed using iommu_put_pages_list(), without messing up refcounts in the tail pages. I think having a dedicated function that guarantees order = 0 pages allocation makes it easier for the reviewer to follow the code, and ensures that only these pages are put on the freelist. Even in the existing code, the order=0 allocation is wrapped in the *alloc_pgtable_page() function. Pasha > > Thanks, > Robin.