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b=BXHTe6JlRHJI012S0SuvFLn9uaAIOB7VWzPs3Fc2RrvXQY5D4HDVHpRkj47d9XWrR Rqmv8FGCbZmOY3AnKFP18XjGJGyiWGrQvL9LpD5uhTF+5Mm03Ufbe/sK93++OBqyK8 P4QODxqj6N9VjEz+gQ7LbzBBhN/beCq5B7ALE2qhb2mFxfLuCZpa072Ob8MofZGULg VUzUfHZpICSgKKpG6xGbj3UzgNOVTY86wBWkdV6YuxNx1XFcdsAMB2JPp5icQuUL1o +GD9dfjNQ9fZ3XbVLlPNOQeQnk673Tqfu0q1pBZKAYFZN8YTDPyMNaEpSqR8sOZzZt CUy1bSrbsGcHQ== Date: Mon, 31 Mar 2025 11:57:28 +0200 From: Ingo Molnar To: Baoquan He Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, yanjun.zhu@linux.dev, x86@kernel.org Subject: Re: [PATCH v2 6/7] x86/mm: remove p4d_leaf definition Message-ID: References: <20250331081327.256412-1-bhe@redhat.com> <20250331081327.256412-7-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250331081327.256412-7-bhe@redhat.com> X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 825A340008 X-Stat-Signature: w6wo6b6gr7rhijiigcwmu4jssjgqhrjq X-HE-Tag: 1743415055-702134 X-HE-Meta: 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 XzZOoflE znIH+707wAA09zSfDUWa4mxFWPE/4AYZRDAl2YMVlOZljNxDKJohnqM5qkqBC9LZqC40CZA8KDe6ele24ql49U/pJ9llN++38QNf4kP/1VZUmErOGkYSQfvbo1PIZm5+5V6x5al8HZD6fW5owecsONuXkfGYmDcXYNKTWcM2o193y/TvM9Dk/lj1OerQGiK+5nUmG3h1pJBuOmmvg+gOjeEkJovhhqEoRkPV7MABt3mD0LVmgKIaa+5LlwaDV4jgKaAQAVyme8KfQnYdrrr1iiKh6eQ== 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: * Baoquan He wrote: > There's no p4d huge page support yet, let's use the generic definition. > > And also update the BUILD_BUG_ON() in pti_user_pagetable_walk_pmd() > because p4d_leaf() returns boolean value. > -#define p4d_leaf p4d_leaf > -static inline bool p4d_leaf(p4d_t p4d) > -{ > - /* No 512 GiB pages yet */ > - return 0; > -} This comment was also incorrect I believe: 1 PTE entry on x86-64 covers 4K virtual memory, 512 PTE entries make up a 4K pagetable page, and each level of paging adds another level of 512 pagetable entries: - level 0: 4K pages - level 1: 512x 4K = 2MB 'large' pages - level 2: 512x 2MB = 1GB 'huge' pages - level 3: 512x 1GB = 512GB 'PGD' pages - level 4: 512x 512GB = 256TB 'P4D' pages So the above comment should have said '256 TB' pages, unless there's some naming weirdness I missed. Thanks, Ingo