From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qk1-f179.google.com (mail-qk1-f179.google.com [209.85.222.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8277D2248AE for ; Sat, 17 Jan 2026 15:39:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.222.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768664392; cv=none; b=goWkzW9UE6rCHrY2IHrco3JbMrNNT0MlAehFvgwcBbhrmwH4z5dOMVDel1tALAmxHEKz/jznixiNnVnYFMrj+fzxxTwE/jr9qu185jtwdMCzRm7Ah62fqlm81YWG85J8fhAOer28Z2TLuKKAWyREVu/so68uv2hUkJcPR16tZYw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768664392; c=relaxed/simple; bh=c5ukZxvOx3XxqLMLZ0Qq3WedxhGaSgozV+pTMWZLD8k=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=nqUTlhiUyVNtS6Fvi4hPPubi0H5kCgPOf6eBlzlJw4RD4q543JweCFmCDKNFYWy5b5pMPiaBbT1z5TbVsgQl48bb68VsEBp9//GZpGgbZ+1KV1s/4VTH9JzRqKREY3eaHF2MVaHvHDgrbB1fyM7qtSIQve2TWg680KjCaMVBzco= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=Nz2LLOFK; arc=none smtp.client-ip=209.85.222.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Nz2LLOFK" Received: by mail-qk1-f179.google.com with SMTP id af79cd13be357-8c69ffb226eso356725985a.1 for ; Sat, 17 Jan 2026 07:39:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1768664390; x=1769269190; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:feedback-id:from:to:cc:subject:date :message-id:reply-to; bh=MsFwJU0uorXcDejUHSz8mT5Xd1nNN5P7vGbzkPiWNoc=; b=Nz2LLOFKWxMLty6p6md1zG72q5To12QNClOU5AbzDry1rdX2WKl6JxdMhMJ2ut5sLO jchrgckLaNK2YoRUIjA9z7VG/33R0Qx3tzJlEE3YrDQNmQeG8EjV4wNzc4/UIWpHwDVC uOnAvrBEnW1wePra1VQAA+5ordBaxHI49v+EU8w6A89rT4f4JLck8QTZBkMtS73GybrV cYwj14GnwTlLi/bb+a68hjBDWHouPnUX/FjENEUScOZ8vrDN3yoeBkTG/sza2lpvGK4s KSD4HGlkHscgpFSPRy5PYoQpUHoRqHLaIbQs+590bXEk+gcz/rSxkw32Wta2XN6o/EQT NrOQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1768664390; x=1769269190; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:feedback-id:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=MsFwJU0uorXcDejUHSz8mT5Xd1nNN5P7vGbzkPiWNoc=; b=Kn+KUFgQQbk9onZWyK/5AfM/TvTxUV9NcTQOpHO1B26QL7pHMkFwwmaw+e9j4wGMED AOFi3tV1V1pM85NiWaRXJY2aSttGjpJWuJ/2yffrTHf7gLNKR0Dq1UPxOHyGbRtmRCHk nIFN4SmaFgJHb0uEiErzMwvr5g+PnQGIWYSaTuPBWLCk84pI2mAju2SHXMhyttRDhr5X GDbAx5HAavqTNx/l+LmVcTbNvgZmd1tKCFHpNW8fkJYnxjE3BIXlAEmgvVJHT8oMM33R 6VZr9N6Menv5Yhd8CLZa/yGn9xC9zx+hAHT3xoyLk1Vgm2lWU8bgLP3OOF/ddJ8Vu59O cVzA== X-Forwarded-Encrypted: i=1; AJvYcCVhWUUG4es0VUBEDOnlvUIDhpoHKbvpl81ONGReT6SPaUYk4SrfD3J1suEawPtQ0jclnxGJedeV4ZHzfMjvtA==@vger.kernel.org X-Gm-Message-State: AOJu0YwN16iABBoqqEvUmABfn/FJaUB7+zAX7nd0vhvZYNjDymDcqGtF FIzmMJX4caW6I3Aq6NmbJDilUwrCwzRsjCSgfnf6rOJRjAWiOpLZyIik X-Gm-Gg: AY/fxX5zhM27PnlUGcKmW958beqwtOrcGAG2dLA5JZugAYF1cXcdovfXQONgcQNsijr 8yYgGgfGVDpydXYMNHK88d5wdlivZi07KvPtw2i1DjGWqNEFTi3U0iIABWePWHnJqXsU5aQkBib nqtiYwK3CTjkO7UuzxtgHzAgmpwb+bwm6tbSGkAIG37LoQN6mp+fDsRmiICdLN9hBQDkTa50y6U mZPvtCkDeRAN1haHtHmB7+OE3rV7T8UbIS+WaMmoP1TaL+aaqKCxFHYARCNR4QVnZLztn7AtxC5 PHO810nFSw0Y1za0t+EvTqybkou+9PzLdgilQAKqv456UJLqqMmDnQ9A/fsSfgyZyJJBW3dfIQj 3ISY/J11o6UEBe7b2345cmIgbb6PB8VLq1jb26kzg+RGZ3maGSOvNCAQyxhOy6ASeaDO70L7sMK 9c6Vw+FFpwMOXXrWigcXARVkqj+p0fL4923AYLdpeA/kLW54ADb1QJdBumkrn6AVy6jzAyDiKRp gcadBJJb+ze64A= X-Received: by 2002:a05:620a:128a:b0:8c6:a84e:2a2d with SMTP id af79cd13be357-8c6a84e2ee8mr540589085a.31.1768664390250; Sat, 17 Jan 2026 07:39:50 -0800 (PST) Received: from fauth-a2-smtp.messagingengine.com (fauth-a2-smtp.messagingengine.com. [103.168.172.201]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8c6a70f1fe1sm448624185a.0.2026.01.17.07.39.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 17 Jan 2026 07:39:49 -0800 (PST) Received: from phl-compute-02.internal (phl-compute-02.internal [10.202.2.42]) by mailfauth.phl.internal (Postfix) with ESMTP id E79BEF40076; Sat, 17 Jan 2026 10:39:48 -0500 (EST) Received: from phl-frontend-04 ([10.202.2.163]) by phl-compute-02.internal (MEProxy); Sat, 17 Jan 2026 10:39:48 -0500 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefgedrtddtgddufedvudelucetufdoteggodetrf dotffvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfurfetoffkrfgpnffqhgenuceu rghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujf gurhepfffhvfevuffkfhggtggujgesthdtredttddtvdenucfhrhhomhepuehoqhhunhcu hfgvnhhguceosghoqhhunhdrfhgvnhhgsehgmhgrihhlrdgtohhmqeenucggtffrrghtth gvrhhnpeehudfgudffffetuedtvdehueevledvhfelleeivedtgeeuhfegueevieduffei vdenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpegsoh hquhhnodhmvghsmhhtphgruhhthhhpvghrshhonhgrlhhithihqdeiledvgeehtdeigedq udejjeekheehhedvqdgsohhquhhnrdhfvghngheppehgmhgrihhlrdgtohhmsehfihigmh gvrdhnrghmvgdpnhgspghrtghpthhtohepvdeipdhmohguvgepshhmthhpohhuthdprhgt phhtthhopegrlhhitggvrhihhhhlsehgohhoghhlvgdrtghomhdprhgtphhtthhopehprg hulhhmtghksehkvghrnhgvlhdrohhrghdprhgtphhtthhopehlihgrmhdrhhhofihlvght thesohhrrggtlhgvrdgtohhmpdhrtghpthhtohepghgrrhihsehgrghrhihguhhordhnvg htpdhrtghpthhtohepohhjvggurgeskhgvrhhnvghlrdhorhhgpdhrtghpthhtohepsghj ohhrnhefpghghhesphhrohhtohhnmhgrihhlrdgtohhmpdhrtghpthhtoheplhhoshhsih hnsehkvghrnhgvlhdrohhrghdprhgtphhtthhopegrrdhhihhnuggsohhrgheskhgvrhhn vghlrdhorhhgpdhrtghpthhtohepthhmghhrohhsshesuhhmihgthhdrvgguuh X-ME-Proxy: Feedback-ID: iad51458e:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Sat, 17 Jan 2026 10:39:48 -0500 (EST) Date: Sat, 17 Jan 2026 23:39:46 +0800 From: Boqun Feng To: Alice Ryhl Cc: "Paul E. McKenney" , "Liam R. Howlett" , Gary Guo , Miguel Ojeda , =?iso-8859-1?Q?Bj=F6rn?= Roy Baron , Benno Lossin , Andreas Hindborg , Trevor Gross , Danilo Krummrich , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Uladzislau Rezki , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Andrew Ballance , linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, rcu@vger.kernel.org, maple-tree@lists.infradead.org, linux-mm@kvack.org Subject: Re: [PATCH RFC 0/2] rcu box container for Rust + maple tree load_rcu Message-ID: References: <20260116-rcu-box-v1-0-38ebfbcd53f0@google.com> Precedence: bulk X-Mailing-List: rust-for-linux@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 Sat, Jan 17, 2026 at 10:05:18PM +0800, Boqun Feng wrote: > On Sat, Jan 17, 2026 at 01:29:25PM +0000, Alice Ryhl wrote: > > On Sat, Jan 17, 2026 at 09:11:49PM +0800, Boqun Feng wrote: > > > In Rcu + RcuOld design, RcuBox is just a Box > > > because these two pointer types handle reclaim + accesses. > > > > How would that work? Dropping my RcuBox<_> must use kfree_rcu() or > > synchronize_rcu() or it is unsound. So it can't just be a Box. > > > > RcuOld will call synchronize_rcu() before dropping > `P`. And I think we can have an asynchronous drop pointer type like > `RcuOld` that requires `P` is a type like `Box`, One blocker on that is Drop impls cannot be specialized. We probably need a different pointer type like RcuOldAsync... Regards, Boqun > and the drop of `RcuOld, Async>` would be `call_rcu()` > or `kfree_rcu()`. > > Regards, > Boqun > > > Alice