From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BA8A9EE6B69 for ; Fri, 6 Feb 2026 21:43:30 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F1EED6B0096; Fri, 6 Feb 2026 16:43:29 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id ECCFC6B0098; Fri, 6 Feb 2026 16:43:29 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DD86B6B0099; Fri, 6 Feb 2026 16:43:29 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id C9DE86B0096 for ; Fri, 6 Feb 2026 16:43:29 -0500 (EST) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 386A0C177E for ; Fri, 6 Feb 2026 21:43:29 +0000 (UTC) X-FDA: 84415358538.30.F71940C Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf19.hostedemail.com (Postfix) with ESMTP id A49081A0008 for ; Fri, 6 Feb 2026 21:43:27 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=U4NlRDtD; spf=pass (imf19.hostedemail.com: domain of a.hindborg@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=a.hindborg@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1770414207; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=uUrAd8iGiJWWzJk+XvDmhDYDR3i/4tUUap99IjGkiK0=; b=y7J9/ZyIBTQ1U1cU6MRckJY4t6QzVQuvo1THotoqf34iUGcuqVK6vdjY1F09uNNxshsAHs +eQ6o/7F4Y4RwSPcPHbzn1X2dfhMtTB/tDGZWj3ulGuEVJ2KIWOe91yijYJ2c4p/tZY1GX 2kOUr5fpF+YOzx5nVoW1wdCjDkXgKe0= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=U4NlRDtD; spf=pass (imf19.hostedemail.com: domain of a.hindborg@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=a.hindborg@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1770414207; a=rsa-sha256; cv=none; b=YWdxoNwL8X0UMHlZwXoOYXc2ExE/hmyz8guzJKJGCyBHIt40tHYoa89Y9Bes5qzNYCV2q2 OVeGHPQ7bF6vk+QcR7Z6QuIc8ofQAbOucj7qa1PSQdQ6lKoJJdNpzFWwYsmJHKS8tkrC2y +wVdi1biitHqr1B8wPgll0e5NFaGN94= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 0A69560137; Fri, 6 Feb 2026 21:43:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 42824C116C6; Fri, 6 Feb 2026 21:43:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770414206; bh=NgQfAJHzVJF3x25o6e0VGnyxpkVMB6vbImUYVyuSsxg=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=U4NlRDtD9s/gTCacHwCXha31viLPKHOqvB4N2P+g+m2Kx77f5fR+S/sxo/+JbRPCf XXd0vMBthXZhVQl/zLrF6lsQbz7wy883crvpo4sYtOwyknqWxhlFv9hlOQ2Nba6iyc ccwJnQT7dPFQ8hIF3nzPQ7NKcrkLxEfkga3OgAW1Z7BWlep5Plsprdl0nZYKlpajsX I5XgfNVdu7F65TL9j3L5dlRj4vjXOBUKijb/D5tL0x4/rktMS4AHYlop8dcG4E1pit s/j5l2MW40kZk7UR9OL8Q476vIaYDPDXo+yOxxmT+71ldU1iRkHhsrA6QDMAlje0uF IlbLXySC7+xSg== From: Andreas Hindborg To: "Matthew Wilcox (Oracle)" , Tamir Duberstein , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn?= Roy Baron , Benno Lossin , Alice Ryhl , Trevor Gross , Danilo Krummrich , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Andrew Morton , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo Cc: Daniel Gomez , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2 11/11] rust: xarray: add preload API In-Reply-To: <20260206-xarray-entry-send-v2-11-91c41673fd30@kernel.org> References: <20260206-xarray-entry-send-v2-0-91c41673fd30@kernel.org> <20260206-xarray-entry-send-v2-11-91c41673fd30@kernel.org> Date: Fri, 06 Feb 2026 22:43:14 +0100 Message-ID: <874intpmz1.fsf@t14s.mail-host-address-is-not-set> MIME-Version: 1.0 Content-Type: text/plain X-Stat-Signature: q1mz9db4xwx9n9yz6z1u3g663bb8ggbp X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: A49081A0008 X-HE-Tag: 1770414207-557525 X-HE-Meta: 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 asJZKzz1 ILGZDkRmITqsARFBr7ipd60+Jj9MaXrYopDfvQnJqJJaiQeA3SFkoRwxsoYltjHko8/YzDauMJ3fwPcAoPgJkxg6pXPYmVXC/TnypiUT00lugt5Js/YI+A4/XvVuL/1D68/EnqKn6PQZLkQTZowSRCk3pQF+gO+xkXTpYxNlmS4dIL1f8AeCpYZlMaMIBVkpRr9Hpz6efZYcvJzojWxeB2sqyzfBHoWa6kgd4YgL6RGA277fljjSLL32hfxShqFDeWqIgsZVXMo7cSC/y5nB19b2E1J42dNoKMemMDLbbxD1rxIcBRy7m6ML+wjEE5bnJiqc+m8PiFRWybp3x2alWJcRf8A== 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: Andreas Hindborg writes: > Add a preload API that allows preallocating memory for XArray > insertions. This enables insertions to proceed without allocation > failures in contexts where memory allocation is not desirable, such as > in atomic contexts or where reliability is critical. > > The API includes: > > - `XArrayPreloadBuffer` for managing a pool of preallocated nodes. > - `XArrayPreloadNode` representing a single preallocated node. > - Integration with the entry API, allowing `VacantEntry::insert` and > `VacantEntry::insert_entry` to accept an optional preload buffer. > - A new `Guard::insert_entry` method for inserting with preload support. > > The implementation uses a circular buffer to efficiently manage > preallocated nodes. When an insertion would fail due to ENOMEM, the > XArray state API automatically consumes a preallocated node from the > buffer if available. > > Export `radix_tree_node_ctor` from C to enable Rust code to work with the > radix tree node cache. > > Cc: "Liam R. Howlett" > Cc: "Matthew Wilcox (Oracle)" > Signed-off-by: Andreas Hindborg I somehow managed to not include this last bit of detail: commit 09bdfa18f6f879eb42df2e032ad5224eed29eb25 Author: Andreas Hindborg Date: Fri Feb 6 22:38:09 2026 +0100 radix-tree: enable sheaf suppport for kmem_cache The rust null block driver plans to rely on preloading xarray nodes from the radix_tree_node_cachep kmem_cache. Signed-off-by: Andreas Hindborg diff --git a/lib/radix-tree.c b/lib/radix-tree.c index b642f2775e89c..ddd67ce672f5c 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -1599,10 +1599,16 @@ void __init radix_tree_init(void) BUILD_BUG_ON(RADIX_TREE_MAX_TAGS + __GFP_BITS_SHIFT > 32); BUILD_BUG_ON(ROOT_IS_IDR & ~GFP_ZONEMASK); BUILD_BUG_ON(XA_CHUNK_SIZE > 255); - radix_tree_node_cachep = kmem_cache_create("radix_tree_node", - sizeof(struct radix_tree_node), 0, - SLAB_PANIC | SLAB_RECLAIM_ACCOUNT, - radix_tree_node_ctor); + + struct kmem_cache_args args = { + .ctor = radix_tree_node_ctor, + .sheaf_capacity = 64, + }; + + radix_tree_node_cachep = kmem_cache_create( + "radix_tree_node", sizeof(struct radix_tree_node), &args, + SLAB_PANIC | SLAB_RECLAIM_ACCOUNT); + ret = cpuhp_setup_state_nocalls(CPUHP_RADIX_DEAD, "lib/radix:dead", NULL, radix_tree_cpu_dead); WARN_ON(ret < 0); Best regards, Andreas Hindborg