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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E4C0EC433F5 for ; Tue, 26 Apr 2022 23:11:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355996AbiDZXOR (ORCPT ); Tue, 26 Apr 2022 19:14:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48148 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231200AbiDZXON (ORCPT ); Tue, 26 Apr 2022 19:14:13 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 013D15F4E for ; Tue, 26 Apr 2022 16:11:03 -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 ams.source.kernel.org (Postfix) with ESMTPS id 9F709B823EF for ; Tue, 26 Apr 2022 23:11:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 49A8FC385AC; Tue, 26 Apr 2022 23:11:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1651014661; bh=sqQfYjjF/r86CeFsB63WxaaPTzmwp2vYEsl7OATmzNQ=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=AsCel1eBnB72AQnTInD6rZXEgUskgLbFriBxFq7lhRjUiS0uhTSd0ySHV569l7uz7 NKh4+8BLI14VKNIzdgObSUKJH84dEubCGXiEe0lVxK9Wt+Re9LaCHbvNvUlFDnQu3d A2dRMQAKR0irtjQ+dpHJl7IB62L7/hxqtwbCLNOj5B3ncar4JCsj+N/gq/4N9jXj0u jK7+HbJnU4AOM91fLG4YyQzjGosmrTKtSeZGrBEJlFYe61P1KEKrX6viN/UoNeH3TP qCFxmNePlsod0GQ0igPdAvJEhohoy0v28H80CVI0p+Qw6p2e7xgIZA8G+UOwDayQqG vDwQd1EGabydg== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id E92785C0530; Tue, 26 Apr 2022 16:11:00 -0700 (PDT) Date: Tue, 26 Apr 2022 16:11:00 -0700 From: "Paul E. McKenney" To: Christoph Bartoschek Cc: Chris Mason , Giuseppe Scrivano , linux-kernel@vger.kernel.org, "riel@surriel.com" , "viro@zeniv.linux.org.uk" Subject: Re: [PATCH RFC fs/namespace] Make kern_unmount() use synchronize_rcu_expedited() Message-ID: <20220426231100.GL4285@paulmck-ThinkPad-P17-Gen-1> Reply-To: paulmck@kernel.org References: <8E281DF1-248F-4861-A3C0-2573A5EFEE61@fb.com> <20220426065917.3123488-1-bartoschek@google.com> <20220426140919.GD4285@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 27, 2022 at 12:58:34AM +0200, Christoph Bartoschek wrote: > > 3. https://lore.kernel.org/lkml/20220218183114.2867528-1-riel@surriel.com/ > > Refined queue_rcu_work() approach. > > > > #1 should work, but the resulting IPIs are not going to make the real-time > > guys happy. #2 and #3 have been subject to reasonably heavy testing > > and did fix a very similar issue to the one that you are reporting, > > but last I knew there were doubts about the concurrency consequences. > > > > Could you please give at least #3 a shot and see if it helps you? > > I have tried #3 and it works well with my testcases as far as I can see it. Thank you for giving it a try! Al, are further adjustments needed to make this patch cover all the corner cases? Thanx, Paul