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McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Zqiang , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , rcu@vger.kernel.org, linux-mm@kvack.org, Alexander Viro , Christian Brauner References: <20260416091022.36823-1-harry@kernel.org> From: "Vlastimil Babka (SUSE)" In-Reply-To: <20260416091022.36823-1-harry@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 141B4100006 X-Rspamd-Server: rspam12 X-Stat-Signature: 1qme57csn15kjb5ngo6k33jans3n6jgp X-Rspam-User: X-HE-Tag: 1776868214-319654 X-HE-Meta: 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 yUJdFIxJ PxpRRX5cwH7PRzwHWEeno0zNM4SeN0Oop74qw+4nvTdeKaQPXB1L9UYNXI+QGoe2HWyOSSJrn1Pu/5lO1TKhwyPZp/x+Ml53Aj4LvWDHOt9hUuXYb8UifvgmZLUYG+52BEZtTsUIIo0ac9K+seF1r3G7ocSg/Kl8xByQIkCJd0e8VjjQaF8SFWZ6ptJfw2iFjPIlobEjy/FSHqhREZBWiQESrsHGUesh4qkyrIGa76WToBTdzQ+2zk7kZ0+qdeS08QrxWwpVFY7vC8S5AfwYHwFjey/3RSsP8I+RcGnTeNln4IkUSCsBRG8267A== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/16/26 11:10, Harry Yoo (Oracle) wrote: > # Part 1. Allow an 8-byte field to be used as an alternative to > struct rcu_head for 2-argument kvfree_rcu() > (patches 1-2) > > Technically, objects that are freed with k[v]free_rcu() need > only one pointer to link objects, because we already know that > the callback function is always kvfree(). For this purpose, > struct rcu_head is unnecessarily large (16 bytes on 64-bit). > > Allow a smaller, 8-byte field (of struct rcu_ptr type) to be used > with k[v]free_rcu(). Let's save one pointer per slab object. > > I have to admit that my naming skill isn't great; hopefully > we'll come up with a better name than `struct rcu_ptr`. "rcu_ptr" sounds too generic to me. Things like rcu_dereference() talk about "RCU-protected pointer" and it could be misleading that "rcu_ptr" has something to do with this. Only if Paul think it's ok :) But maybe just "kvfree_rcu_head"? As IMHO It's an rcu_head specialized for kvfree.