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 112E1F9EDF9 for ; Wed, 22 Apr 2026 22:41:35 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CA4586B0005; Wed, 22 Apr 2026 18:41:34 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C568B6B008A; Wed, 22 Apr 2026 18:41:34 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B6C336B008C; Wed, 22 Apr 2026 18:41:34 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id A4EE66B0005 for ; Wed, 22 Apr 2026 18:41:34 -0400 (EDT) Received: from smtpin09.hostedemail.com (lb01b-stub [10.200.18.250]) by unirelay09.hostedemail.com (Postfix) with ESMTP id E37498AB7A for ; Wed, 22 Apr 2026 22:41:33 +0000 (UTC) X-FDA: 84687664866.09.074AE07 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf26.hostedemail.com (Postfix) with ESMTP id 22E63140010 for ; Wed, 22 Apr 2026 22:41:31 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=jVsFPXe0; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf26.hostedemail.com: domain of "SRS0=hVWM=CV=paulmck-ThinkPad-P17-Gen-1.home=paulmck@kernel.org" designates 172.105.4.254 as permitted sender) smtp.mailfrom="SRS0=hVWM=CV=paulmck-ThinkPad-P17-Gen-1.home=paulmck@kernel.org" ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1776897692; a=rsa-sha256; cv=none; b=SrLTFMK43gJczV+RUYAfiPrrD9QZio9uVKfq4ViN7rbaPRAPUqIYDga+Z/ZvnnE4xWbdRE utZxOVZcrGhzIgkitBaoMJHBbOF0VIIBMvmonDwZ4NXmqOIYGCAN9SOmC5oT9yKZhZ/7WW MYq3cDAhNy3JsmRDmGs55cPICNn8s9E= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=jVsFPXe0; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf26.hostedemail.com: domain of "SRS0=hVWM=CV=paulmck-ThinkPad-P17-Gen-1.home=paulmck@kernel.org" designates 172.105.4.254 as permitted sender) smtp.mailfrom="SRS0=hVWM=CV=paulmck-ThinkPad-P17-Gen-1.home=paulmck@kernel.org" ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1776897692; h=from:from:sender:reply-to: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=FxcUPO4equ3YjCkaPjz6cR8CN+AW5BC+3S72FPsJ/M0=; b=dbid5DiFRv85dtkHTxFXUnkqfgZsXt8ivGw8TyER214GH9R+XlbiC0CQKFK1B7Tlh7fLcd NmC2YEhiQPNW8Wi8g2K4AT3iXgDp7/28iMilJ7vxv0Hln5K2JdCy4BEMSWv1wgPGyC9F1p sgskwJHBYNBia+FWb+hQEiVGztCZv0M= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 2731361334; Wed, 22 Apr 2026 22:41:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C8D1EC19425; Wed, 22 Apr 2026 22:41:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776897690; bh=gUEK152lwoAI8GlkDU0asgwfk5vJmlbdfCMd5yE1mWI=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=jVsFPXe0khsDOZDfOQ+bRAR84cRTacJtOLZZQutTo2qDX+EN0fm28b7fxoVRqxBj4 pQxBC8IycM8qZcApMlBirU+WSma8HFjtRP3g7fAeGHr8a8uSirwpxrRRy+7zHgqH0x Qx+du/HEepHE4dQH/OyJ4MUBW5Sk7u9oSyI+GZQfYZv/Ah8Io76ofNDMHynqNIDVpR DsDbf5DjF14ejzWupQM+vSQAVmgZs/gcSA0oQ0KTVqkHoC3yPMSw1o2s9uME/3FhZC tatpnlqShTcBapfl+ujtXTQqZtTyDTSaRVDy6WWnmyMfIq2b5evJL2CX3AUTxdENjc enKVgqr8rO7Fw== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 6987BCE129B; Wed, 22 Apr 2026 15:41:30 -0700 (PDT) Date: Wed, 22 Apr 2026 15:41:30 -0700 From: "Paul E. McKenney" To: "Vlastimil Babka (SUSE)" Cc: "Harry Yoo (Oracle)" , Andrew Morton , Christoph Lameter , David Rientjes , Roman Gushchin , Hao Li , Alexei Starovoitov , Uladzislau Rezki , 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 Subject: Re: [RFC PATCH v2 0/8] kvfree_rcu() improvements Message-ID: Reply-To: paulmck@kernel.org References: <20260416091022.36823-1-harry@kernel.org> <214ca3ac-45b7-4131-86e5-ac134ab0bcbd@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <214ca3ac-45b7-4131-86e5-ac134ab0bcbd@kernel.org> X-Rspamd-Server: rspam10 X-Stat-Signature: wbdgqqe1oqr96654z6fbw19a5ebkc74f X-Rspam-User: X-Rspamd-Queue-Id: 22E63140010 X-HE-Tag: 1776897691-271362 X-HE-Meta: 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 3O2UWVsI 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Apr 22, 2026 at 04:30:07PM +0200, Vlastimil Babka (SUSE) wrote: > 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. What is in a name? ;-) I do have a slight preference for kvfree_rcu_head. Thanx, Paul