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[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: 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 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