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 5C22FC25B0F for ; Sat, 13 Aug 2022 13:43:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239418AbiHMNnw (ORCPT ); Sat, 13 Aug 2022 09:43:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47644 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238887AbiHMNnu (ORCPT ); Sat, 13 Aug 2022 09:43:50 -0400 Received: from jabberwock.ucw.cz (jabberwock.ucw.cz [46.255.230.98]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C7C15DEA9; Sat, 13 Aug 2022 06:43:38 -0700 (PDT) Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id 015591C0006; Sat, 13 Aug 2022 15:43:37 +0200 (CEST) Date: Sat, 13 Aug 2022 15:43:34 +0200 From: Pavel Machek To: Sasha Levin Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Sebastian Andrzej Siewior , Oleg.Karfich@wago.com, Thomas Gleixner , Al Viro , linux-fsdevel@vger.kernel.org Subject: Re: [PATCH AUTOSEL 4.19 14/14] fs/dcache: Disable preemption on i_dir_seq write side on PREEMPT_RT Message-ID: <20220813134334.GA24517@duo.ucw.cz> References: <20220811160948.1542842-1-sashal@kernel.org> <20220811160948.1542842-14-sashal@kernel.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="6c2NcOVqGQ03X4Wi" Content-Disposition: inline In-Reply-To: <20220811160948.1542842-14-sashal@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org --6c2NcOVqGQ03X4Wi Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi! > From: Sebastian Andrzej Siewior >=20 > [ Upstream commit cf634d540a29018e8d69ab1befb7e08182bc6594 ] >=20 > i_dir_seq is a sequence counter with a lock which is represented by the > lowest bit. The writer atomically updates the counter which ensures that = it > can be modified by only one writer at a time. This requires preemption to > be disabled across the write side critical section. >=20 > On !PREEMPT_RT kernels this is implicit by the caller acquiring > dentry::lock. On PREEMPT_RT kernels spin_lock() does not disable preempti= on This should not be applied to 4.19 as CONFIG_PREEMPT_RT does not exist there. Best regards, Pavel --=20 'DENX Software Engineering GmbH, Managing Director: Wolfgang Denk' 'HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany' --6c2NcOVqGQ03X4Wi Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EABECAB0WIQRPfPO7r0eAhk010v0w5/Bqldv68gUCYveqhgAKCRAw5/Bqldv6 8jB7AJ9kB9Ep7hzmzZvri5e6Cl+NElOtSACgtrJkx7JKO87b2TS/jWh66brZ6YI= =LuVS -----END PGP SIGNATURE----- --6c2NcOVqGQ03X4Wi--