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Fri, 20 Feb 2026 07:12:38 -0500 (EST) Date: Fri, 20 Feb 2026 12:12:33 +0000 From: Kiryl Shutsemau To: David Laight Cc: lsf-pc@lists.linux-foundation.org, linux-mm@kvack.org, x86@kernel.org, linux-kernel@vger.kernel.org, Andrew Morton , David Hildenbrand , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , Matthew Wilcox , Johannes Weiner , Usama Arif Subject: Re: [LSF/MM/BPF TOPIC] 64k (or 16k) base page size on x86 Message-ID: References: <20260220090409.1784bc64@pumpkin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260220090409.1784bc64@pumpkin> X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: ED79E180015 X-Stat-Signature: 8d4owzgcc15js4m5aq5pd6okgf4ub1u1 X-HE-Tag: 1771589562-383543 X-HE-Meta: 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 vRpQawUo YxOy/W4ViqoTkcow8SiAMdwfx3kM782vDMdrwb/T7W9bI9+iwBMKaYubMtAMnEohJnupkK3/7X+yiO0KS6exuqJAaGJywTbBSA9d3SSoXn0Vv7YWT2x9CyM9NX6BLmhBHv/tRk19Ptb9n8BedhslJujXQDdBxh9Yr8l6PtXh8W77m1AxvgYzN9POmN7YJgfZOx21UbF/tJdIMcp+k9eQeo4/aZVJ2VSOocNRiJ7xemf+dda7e99NzE6Z8sKz/BSS/8FZNSsZSaxA5NQXrJBEfDFXwBMlx4eeAz+8ykkwHe//JW9SbI3bcXcqVys9bLs04SjN4lUqUmVHad8RRhpBGu3K8qebzJM1Q8Fot3dODHypV4HIH/zooe+H3/w== 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: On Fri, Feb 20, 2026 at 09:04:09AM +0000, David Laight wrote: > On Thu, 19 Feb 2026 15:08:51 +0000 > Kiryl Shutsemau wrote: > > > No, there's no new hardware (that I know of). I want to explore what page size > > means. > > > > The kernel uses the same value - PAGE_SIZE - for two things: > > > > - the order-0 buddy allocation size; > > > > - the granularity of virtual address space mapping; > > Also the 'random' buffers that are PAGE_SIZE rather than 4k. Yeah, in some places we use PAGE_SIZE just because without any reason. > I also wonder how is affects mmap of kernel memory and the alignement > of PCIe windows (etc). Kernel, as userspace, is free to map memory PTE_SIZE granularity. -- Kiryl Shutsemau / Kirill A. Shutemov