From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 70DEA32B9A3 for ; Thu, 19 Feb 2026 22:26:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771539988; cv=none; b=in1conqNkjE8MIiCuEIAI/ntqaJv4P9knIHiAKQ0FTAYLpS0ndNhLK19FhY+SrGrTVKeMORUn3Ac/uCxK5qXIawoYqU2VfocvpCh7a2q+vwnJkKp7FMYU/R9I3VuqbOgMq+/KP81+KxShz2/JFOfTFbbxosOKVdrxRILxEPArnI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771539988; c=relaxed/simple; bh=orBN2LBkIf7igHtr8R6CLAmIl24SfmbjXYa/a8WFlcI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=A1/o7n2htj3uM5pGjd2S9risugXSqVrUqnT6rbnhxJoMXOu4gOUPQbIxQXo6bKv3Bvtso+ViSWTnQQSloB8Vpq4ZpYNRCHNWPUweTxiheOT8vyeD24NU+VyLG4aznq9ksHSgo+9IuUyqHtLxoapXE5UesUKl/08On4TBWKqzVqU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KT9MBj8D; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="KT9MBj8D" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5EC18C4CEF7; Thu, 19 Feb 2026 22:26:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771539988; bh=orBN2LBkIf7igHtr8R6CLAmIl24SfmbjXYa/a8WFlcI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KT9MBj8D3xUAiRCGuRRmOHbbH/0nU5BhYau706AjTPaNf54+z/9Td2KBPtmwcBL/w YJbXUGWiqxohvGPc68CgX1g8hFidjZHpabX4z66EYE0o0l7QLA7oPyXeGGoKMrEoLG d7wrAHKYGxLqwQ+YMMRpb+Q7HTUgCp/9wUwnk6IT4oz2vm+5bXH7Z7+3BwENq4f/ay INLVluaO0QSJsTUBXOwT/9mY7Rqy2BcWJPHMpDRTS/TnFm75igyLF5BFfL5XySvbn0 LTHbZwG3Cp3PwjcdPvQyCDpJeHqiNSqnlaGAEepmFUU0PEcXf0mSjCPOIhRB7WYdcP gAW1RLGgnA02w== Received: from phl-compute-05.internal (phl-compute-05.internal [10.202.2.45]) by mailfauth.phl.internal (Postfix) with ESMTP id 66BFDF40068; Thu, 19 Feb 2026 17:26:26 -0500 (EST) Received: from phl-frontend-03 ([10.202.2.162]) by phl-compute-05.internal (MEProxy); Thu, 19 Feb 2026 17:26:26 -0500 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefgedrtddtgddvvdeijeegucetufdoteggodetrf dotffvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfurfetoffkrfgpnffqhgenuceu rghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujf gurhepfffhvfevuffkfhggtggujgesthdtredttddtvdenucfhrhhomhepmfhirhihlhcu ufhhuhhtshgvmhgruhcuoehkrghssehkvghrnhgvlhdrohhrgheqnecuggftrfgrthhtvg hrnhepueeijeeiffekheeffffftdekleefleehhfefhfduheejhedvffeluedvudefgfek necuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomhepkhhirh hilhhlodhmvghsmhhtphgruhhthhhpvghrshhonhgrlhhithihqdduieduudeivdeiheeh qddvkeeggeegjedvkedqkhgrsheppehkvghrnhgvlhdrohhrghesshhhuhhtvghmohhvrd hnrghmvgdpnhgspghrtghpthhtohepfedvpdhmohguvgepshhmthhpohhuthdprhgtphht thhopeifihhllhihsehinhhfrhgruggvrggurdhorhhgpdhrtghpthhtoheplhhsfhdqph gtsehlihhsthhsrdhlihhnuhigqdhfohhunhgurghtihhonhdrohhrghdprhgtphhtthho pehlihhnuhigqdhmmheskhhvrggtkhdrohhrghdprhgtphhtthhopeigkeeisehkvghrnh gvlhdrohhrghdprhgtphhtthhopehlihhnuhigqdhkvghrnhgvlhesvhhgvghrrdhkvghr nhgvlhdrohhrghdprhgtphhtthhopegrkhhpmheslhhinhhugidqfhhouhhnuggrthhioh hnrdhorhhgpdhrtghpthhtohepuggrvhhiugeskhgvrhhnvghlrdhorhhgpdhrtghpthht ohepthhglhigsehlihhnuhhtrhhonhhigidruggvpdhrtghpthhtohepmhhinhhgohesrh gvughhrghtrdgtohhm X-ME-Proxy: Feedback-ID: i10464835:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 19 Feb 2026 17:26:25 -0500 (EST) Date: Thu, 19 Feb 2026 22:26:22 +0000 From: Kiryl Shutsemau To: Matthew Wilcox 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 , Johannes Weiner , Usama Arif Subject: Re: [LSF/MM/BPF TOPIC] 64k (or 16k) base page size on x86 Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Feb 19, 2026 at 05:47:22PM +0000, Matthew Wilcox wrote: > On Thu, Feb 19, 2026 at 03:08:51PM +0000, Kiryl Shutsemau wrote: > > On x86, page tables are allocated from the buddy allocator and if PG_SIZE > > is greater than 4 KB, we need a way to pack multiple page tables into a > > single page. We could use the slab allocator for this, but it would > > require relocating the page-table metadata out of struct page. > > Have you looked at the s390/ppc implementations (yes, they're different, > no, that sucks)? No, will check it out tomorrow. > slab seems like the wrong approach to me. I was the first thing that came to mind. I have not put much time into it > There's a third approach that I've never looked at which is to allocate > the larger size, then just use it for N consecutive entries. Yeah, that's a possible way. We would need to populate 16 page table entries of the parent page table. But you don't need to care about fragmentation within the page. -- Kiryl Shutsemau / Kirill A. Shutemov