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bh=ENY+GBR80KU6FtfZoQp38Y0wG9dMpgJdlLMVkzCZzJE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Wjo0r9oqO32DtHsSgog4dZlLy2/yDQdDAw64BfeonhYX4lVHGZbVXbsyIO3Md4aga h3kaE7NvslJinmYlrUPegQ6ZDM82vnE32bczkZKoDJFwPHpai+q+bVidl7Kv5ww6Y8 Yz3iS+Cq4gGpECGWacXSF/BYmOSMe1o6Xl4K5EO2M7zzrXeZBiH5/JJ1xYZUhZNygI A2XzXx71LFnXiSzSJJHdQBM9p+R6Trqhtz03VkKdOSrunFKjWF0doUX9zig0W3kXDq jCpyYraSmQ3/cmqI3nYYOZHLv4T3si8alVdJZ6HVyJG7eyY4LZsbQW23NGtYIT6vYb /Eg/cPuwvTteA== Date: Thu, 8 Jun 2023 12:00:56 +0300 From: Mike Rapoport To: Linus Walleij Cc: Matthew Wilcox , Andrew Morton , Jonathan Corbet , linux-mm@kvack.org, linux-doc@vger.kernel.org Subject: Re: [PATCH] Documentation/mm: Initial page table documentation Message-ID: <20230608090056.GH52412@kernel.org> References: <20230605221035.3681812-1-linus.walleij@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Queue-Id: 0701A140017 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: 5q5b3go5tujy9fknouwn99fkixky9j5x X-HE-Tag: 1686214882-4517 X-HE-Meta: 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 INXJRO/k jT7fgnzCBmPoOhvYzDQTUIW+5VJWBlNtCXAesNo/FNvTLvmWLphbHUpz0/Octfq5OhqXQjej6DvDxmzmAUMkpuiU20aQeep9+oLvzFzAYWX2/EvIgLzii+nSFbm6gAfUnxHnkyuIt79qsYgAGL771xln46jPygZmlVWDhhpfufRown9YogbL3y+SOIv76R9rhlccaL29mJ5pzm9dARzP40p2VfBpK/rzF/j5lC56YEQGNn067gw2x1fw5C1OABs5RU63BDM57+OZT5lonaqw0+ieP2WmnPoLT1rkuyWzDI8vpxNTmEIp0iwjI9HsQMEayuQJNp1mPPZGiJ+uZkFeyfzAO6A== 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: On Thu, Jun 08, 2023 at 10:13:49AM +0200, Linus Walleij wrote: > Hi Matthew, > > I fixes up most of the comments. > > On Tue, Jun 6, 2023 at 5:57 AM Matthew Wilcox wrote: > > On Tue, Jun 06, 2023 at 12:10:35AM +0200, Linus Walleij wrote: > > > > +- **pte**, `pte_t`, `pteval_t` = **Page Table Entry** - mentioned earlier. > > > + The name is a bit confusing because while in Linux 1.0 this did refer to a > > > + single page table entry in the top level page table, it was retrofitted > > > + to be "what the level above points to". So when two-level page tables were > > > + introduced, the *pte* became a list of pointers, which is why > > > + `PTRS_PER_PTE` exists. This oxymoronic term can be mildly confusing. > > > > I don't think this is right. PTRS_PER_PTE is how many pointers are in > > the PMD page table, > > I don't get this. What does PTRS_PER_PMD mean then (and > then all the way up to PTRS_PER_PGD...) PTRS_PER_PTE is how many pointers in the lowest level (pte) page table and pte_t is a "pointer" to an actual physical page mapped by the page tables. > Yours, > Linus Walleij -- Sincerely yours, Mike.