From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B01FE21CC71 for ; Thu, 23 Apr 2026 01:31:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776907879; cv=none; b=A78bBTlaNMo7DyomKLKXGzUyRsG2ZOsHMo81BpmenhqXjvy808wsyRwVgEoc+aXx+qJMkXJvu0vSAnbM3OnTeQz9EuKt+RS5Nnnj4AiUxN+rMbiSgw0jTxL++PKjumqazjJKTCdKiZqfHjdUP5bnfRBYItnux80srlb+ge0kFMM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776907879; c=relaxed/simple; bh=jlAGtqvwrlvzYzSmfvFrSnoSFtUA9CDJqYVY/DrcyQE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=grZYRv8+OohXIsnBKNWNSMrCdkcpBwxVakHxPh2zjWTnNyrrrpjMNzMaBwR5yFuf2CxHvamKQx5ywe6QL4Eb3pyrgVWeRi4+ta8LmV2iy6+SW9gOcDERby/ZCmwsgqa+uUdRCTKU9b+xj5ZfNtXJkVbSV5G51PXCU4j9m+S8RYI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZEJZWo7I; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZEJZWo7I" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DFFCAC19425; Thu, 23 Apr 2026 01:31:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776907879; bh=jlAGtqvwrlvzYzSmfvFrSnoSFtUA9CDJqYVY/DrcyQE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ZEJZWo7IQJuIGCKRZDR/ii0H6m9xm9EV9uOtNDrN0f8QCeqLoedks257e0Mte/UCw K5+jGRaevfQ5qE+RMQzQ+nXMSoOHIhQC7rwC4oXhV1gxV4htVQUfw743nLlosIzf9g vYk53ptKBWwJ20msbQngDer/b42Yew2NBQhJezXnlYq4uckN2HOunUPC4eYb3XrTMV 5SjtxITuoDs3apa4uPiphxFQvVF7ggKuZMx3jaQmLSbibTgethbcUWXDK9PNxtIhOs V2entigvS7oOgS4YQ/hwA1sJI9gh76lTD8zXpFw7HpVIDrG28elz6SfcTk7WrXLne4 p5tFoFwXqPwJA== Date: Thu, 23 Apr 2026 10:31:17 +0900 From: "Harry Yoo (Oracle)" To: "Vlastimil Babka (SUSE)" Cc: Andrew Morton , Christoph Lameter , David Rientjes , Roman Gushchin , Hao Li , Alexei Starovoitov , Uladzislau Rezki , "Paul E . 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 Subject: Re: [RFC PATCH v2 0/8] kvfree_rcu() improvements Message-ID: References: <20260416091022.36823-1-harry@kernel.org> <214ca3ac-45b7-4131-86e5-ac134ab0bcbd@kernel.org> Precedence: bulk X-Mailing-List: rcu@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: <214ca3ac-45b7-4131-86e5-ac134ab0bcbd@kernel.org> 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. to me too ;) > Things like rcu_dereference() talk about > "RCU-protected pointer" and it could be misleading that "rcu_ptr" has > something to do with this. Agreed. > But maybe just "kvfree_rcu_head"? As IMHO It's an rcu_head specialized for > kvfree. I like the name better and will rename it, thanks! -- Cheers, Harry / Hyeonggon