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 X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6AC74C433B4 for ; Thu, 29 Apr 2021 18:49:45 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 68AA461408 for ; Thu, 29 Apr 2021 18:49:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 68AA461408 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id ABF416B0036; Thu, 29 Apr 2021 14:49:43 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A6F5B6B006E; Thu, 29 Apr 2021 14:49:43 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 910746B0070; Thu, 29 Apr 2021 14:49:43 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0076.hostedemail.com [216.40.44.76]) by kanga.kvack.org (Postfix) with ESMTP id 754C86B0036 for ; Thu, 29 Apr 2021 14:49:43 -0400 (EDT) Received: from smtpin35.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 23DEE180ACF1F for ; Thu, 29 Apr 2021 18:49:43 +0000 (UTC) X-FDA: 78086293446.35.C1015B2 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf17.hostedemail.com (Postfix) with ESMTP id 731C440002CF for ; Thu, 29 Apr 2021 18:49:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=0dfv+SpEYuBEoQs4wiKFRhD+0Q3NTeyzHUqYGaZb7Wk=; b=bRq9ONSpF0k+zDoO5t39WyTOvc RddRmbO6JlqbMu5RCO/6ldfnnQc+Ancu95kwWHJB0p+EbC2yxY80PIgwt0s+ykddfQC2/l0lWsqju +4wQHrzFJ3HWMGKkADvAF5eMza2wmWYujHuZazW2dElckRGmtyGYwVI38q5ht0F/xe0SaYIJV8exC sWZRIVHoDuF4fcHBvGvMTfgW+vCMYJK7jz+As8dKlzUkB84b1rytwuRz+sbQuXzZ8TJywfUPQp2Ho GBXo6XHdjYEdJuHn+T9oRQ4KUkWfrf3Jng/0nf/Mz3BZ4h1N7T+r++Lem2b7eXV1UMXSmSSjuu1vf p5iwqrnQ==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1lcBim-00A0d2-3F; Thu, 29 Apr 2021 18:49:20 +0000 Date: Thu, 29 Apr 2021 19:49:08 +0100 From: Matthew Wilcox To: "Paul E. McKenney" Cc: Michel Lespinasse , Andy Lutomirski , Linux-MM , Laurent Dufour , Peter Zijlstra , Michal Hocko , Rik van Riel , Andrew Morton , Suren Baghdasaryan , Joel Fernandes , Rom Lemarchand , Linux-Kernel Subject: Re: [RFC PATCH 13/37] mm: implement speculative handling in __handle_mm_fault(). Message-ID: <20210429184908.GH1847222@casper.infradead.org> References: <20210407014502.24091-1-michel@lespinasse.org> <20210407014502.24091-14-michel@lespinasse.org> <20210428145823.GA856@lespinasse.org> <20210428161108.GP975577@paulmck-ThinkPad-P17-Gen-1> <20210429000225.GC10973@lespinasse.org> <20210429155250.GV975577@paulmck-ThinkPad-P17-Gen-1> <20210429183412.GA278623@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210429183412.GA278623@paulmck-ThinkPad-P17-Gen-1> X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 731C440002CF X-Stat-Signature: ujq5sq1syqp3mff6hokgm8gsypyb31uy Received-SPF: none (infradead.org>: No applicable sender policy available) receiver=imf17; identity=mailfrom; envelope-from=""; helo=casper.infradead.org; client-ip=90.155.50.34 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1619722178-521849 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Apr 29, 2021 at 11:34:12AM -0700, Paul E. McKenney wrote: > +++ b/include/linux/rcupdate.h > @@ -532,7 +532,10 @@ do { \ > * @p: The pointer to read, prior to dereferencing > * @c: The conditions under which the dereference will take place > * > - * This is the RCU-bh counterpart to rcu_dereference_check(). > + * This is the RCU-bh counterpart to rcu_dereference_check(). However, > + * please note that in recent kernels, synchronize_rcu() waits for > + * local_bh_disable() regions of code in addition to regions of code > + * demarked by rcu_read_lock() and rcu_read_unlock(). > */ I've been trying to get rid of "please note that" in my own documentation recently. It doesn't add any value. Also, "recent kernels" is going to go stale quickly, "Since v5.8" (or whatever) is good because it lets us know in ten years that we can just delete the reference. So I'd make this: * This is the RCU-bh equivalent of rcu_dereference_check(). Since v5.8, * synchronize_rcu() waits for code with bottom halves disabled as well * as code between rcu_read_lock() and rcu_read_unlock().