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 02F40C433EF for ; Mon, 23 May 2022 21:16:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229518AbiEWVQ1 (ORCPT ); Mon, 23 May 2022 17:16:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56208 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231926AbiEWVQB (ORCPT ); Mon, 23 May 2022 17:16:01 -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 5EBDD63BA for ; Mon, 23 May 2022 14:16:00 -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 0DE18B8162F for ; Mon, 23 May 2022 21:15:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B4CD5C385AA; Mon, 23 May 2022 21:15:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1653340557; bh=TYuQ4D99n0wp34u9KogOnbairlXFOr2wKFW0BS03Og8=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=GtIYd7Euludu53MDYJvzeeUWiZ2UlpU+fF4QH5WZ4knZWJmA9wdS3dO9Fasym75b0 4QYfFwWdm1i6zS1om/GNF3+JLEbLHP90TOgAAjt5WjXlXWwLffVJVUe9ALhfMLF9oo Cyk24L+ybu9ge7K3p5xCs2GNvYEwzu7a92Ri1uTV+/84IZN/MzIGdh6Jf/EbzB2EF3 v51jzV0I6yDoQ84aHLu3+e/wIq7VTZqnvGv6ZlsEM1bDoVoxG2hDdCXrAWy6l6ISGY n1RsaddEIYvZDWMfLgzoT3espDPLfWIGgHEJMslaYvz6noL9hMUQklzcjlLBXEzdDD Z2k7KJECYz1Lg== Message-ID: Subject: Re: [PATCH RFC] NFSD: Fix possible sleep during nfsd4_release_lockowner() From: Jeff Layton To: "J. Bruce Fields" Cc: Chuck Lever III , Trond Myklebust , Linux NFS Mailing List Date: Mon, 23 May 2022 17:15:55 -0400 In-Reply-To: <20220523202938.GJ24163@fieldses.org> References: <510282CB-38D3-438A-AF8A-9AC2519FCEF7@oracle.com> <1A37E2B5-8113-48D6-AF7C-5381F364D99E@oracle.com> <93d11e12532f5a10153d3702100271f70373bce6.camel@hammerspace.com> <5dfbc622c9ab70af5e4a664f9ae03b7ed659e8ac.camel@hammerspace.com> <17007994486027de807d80dfde1a716c3d127de1.camel@kernel.org> <20220523202938.GJ24163@fieldses.org> Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.44.1 (3.44.1-1.fc36) MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Mon, 2022-05-23 at 16:29 -0400, J. Bruce Fields wrote: > On Mon, May 23, 2022 at 03:36:27PM -0400, Jeff Layton wrote: > > The other lockowner _is_ involved. It's the one holding the conflicting > > lock. nfs4_set_lock_denied copies info from the conflicting lockowner > > into the LOCK/LOCKT response. That's safe now because it holds a > > reference to the owner. At one point it wasn't (see commit aef9583b234a= 4 > > "NFSD: Get reference of lockowner when coping file_lock", which fixed > > that). >=20 > I doubt that commit fixed the whole problem, for what it's worth. What > if the client holding the conflicting lock expires before we get to > nfs4_set_lock_denied? >=20 Good point -- stateowners can't hold a client reference. clientid_t is 64 bits, so one thing we could do is just keep a copy of that in the lockowner. That way we wouldn't need to dereference so_client in nfs4_set_lock_denied. Maybe there are better ways to fix it though. --=20 Jeff Layton