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[2620:137:e000::1:20]) by mx.google.com with ESMTP id bs184-20020a6328c1000000b005073e3342eesi1249826pgb.143.2023.05.23.05.18.55; Tue, 23 May 2023 05:19:12 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=DJ2qIB74; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236740AbjEWMJV (ORCPT + 99 others); Tue, 23 May 2023 08:09:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43480 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236349AbjEWMJU (ORCPT ); Tue, 23 May 2023 08:09:20 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C4943118; Tue, 23 May 2023 05:09:19 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 605EB6117C; Tue, 23 May 2023 12:09:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E9E9DC433D2; Tue, 23 May 2023 12:09:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1684843758; bh=3HvMiLwSxwQEG8Ntmcawz72NdT2pUbel5Q8Sk7Zjzik=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=DJ2qIB74oDOP+PUdnYONaOPP2l2LQGFy/WVyW1zNXHabrGks7kUzGD+Oh8zH3hO8w FD7fwqyB58gRA9260iNFdDIkIX60E6tFGmX+7enMxHmTSGvRrutzOkNcD2Y14/cSfJ 1FluobWOkijaPdBgyxPv1hUEpLPCkTDdjxLsKjfd9XevhkcRd1xN+fxjPqLTJnqPg3 bXmdRyvpwgOTeoPgCoR+0hJF5gRv5Lb0OsuG1lxUN7B4Zyn6ymo3qlRDNUjugjWito /x3quZKgWRZQBbpi4ClKR3b8Ey5XZwYT+usTx63Bqcbmdh1kj5xdD2OL/hM9fpuww3 VtqMoRCM6ysWQ== Date: Tue, 23 May 2023 14:09:12 +0200 From: Christian Brauner To: Michal =?utf-8?Q?Koutn=C3=BD?= Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Alexander Viro , Tejun Heo , Zefan Li , Johannes Weiner , Dave Chinner , Rik van Riel , Jiri Wiesner Subject: Re: [RFC PATCH 0/3] Rework locking when rendering mountinfo cgroup paths Message-ID: <20230523-salamander-gemeldet-b549ea345cf8@brauner> References: <20230502133847.14570-1-mkoutny@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20230502133847.14570-1-mkoutny@suse.com> X-Spam-Status: No, score=-7.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_HI, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 02, 2023 at 03:38:44PM +0200, Michal Koutný wrote: > Idea for these modification came up when css_set_lock seemed unneeded in > cgroup_show_path. > It's a delicate change, so the deciding factor was when cgroup_show_path popped > up also in some profiles of frequent mountinfo readers. > The idea is to trade the exclusive css_set_lock for the shared > namespace_sem when rendering cgroup paths. Details are described more in I have no issue with the cgroup specific part of relying on namespace_sem but kernel/cgroup/ has no business of being aware of namespace semaphore in any way. Leave a comment to clarify what you're doing but we're not going to sprinkle namespace_sem references - even if only for the sake of lockdep - into other subsystems.