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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 F1A02C4727C for ; Wed, 30 Sep 2020 16:22:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A61182085B for ; Wed, 30 Sep 2020 16:22:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728076AbgI3QW5 (ORCPT ); Wed, 30 Sep 2020 12:22:57 -0400 Received: from jabberwock.ucw.cz ([46.255.230.98]:51078 "EHLO jabberwock.ucw.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725800AbgI3QW5 (ORCPT ); Wed, 30 Sep 2020 12:22:57 -0400 Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id 0EE5A1C0B81; Wed, 30 Sep 2020 18:22:55 +0200 (CEST) Date: Wed, 30 Sep 2020 18:22:54 +0200 From: Pavel Machek To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Anton Eidelman , Sagi Grimberg , Christoph Hellwig , Sasha Levin Subject: Re: [PATCH 4.19 196/245] nvme: fix possible deadlock when I/O is blocked Message-ID: <20200930162254.GB23434@duo.ucw.cz> References: <20200929105946.978650816@linuxfoundation.org> <20200929105956.511527430@linuxfoundation.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="9zSXsLTf0vkW971A" Content-Disposition: inline In-Reply-To: <20200929105956.511527430@linuxfoundation.org> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org --9zSXsLTf0vkW971A Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi! > [ Upstream commit 3b4b19721ec652ad2c4fe51dfbe5124212b5f581 ] >=20 > Revert fab7772bfbcf ("nvme-multipath: revalidate nvme_ns_head gendisk > in nvme_validate_ns") >=20 > When adding a new namespace to the head disk (via nvme_mpath_set_live) > we will see partition scan which triggers I/O on the mpath device node. > This process will usually be triggered from the scan_work which holds > the scan_lock. If I/O blocks (if we got ana change currently have only > available paths but none are accessible) this can deadlock on the head > disk bd_mutex as both partition scan I/O takes it, and head disk revalida= tion > takes it to check for resize (also triggered from scan_work on a different > path). See trace [1]. >=20 > The mpath disk revalidation was originally added to detect online disk > size change, but this is no longer needed since commit cb224c3af4df > ("nvme: Convert to use set_capacity_revalidate_and_notify") which already > updates resize info without unnecessarily revalidating the disk (the > mpath disk doesn't even implement .revalidate_disk fop). Commit cb224c3af4df ("nvme: Convert to use set_capacity_revalidate_and_notify") is not in 4.19-stable. Does that mean we'll no longer detect disk size changes after this? Best regards, Pavel > index faa7feebb6095..84fcfcdb8ba5f 100644 > --- a/drivers/nvme/host/core.c > +++ b/drivers/nvme/host/core.c > @@ -1599,7 +1599,6 @@ static void __nvme_revalidate_disk(struct gendisk *= disk, struct nvme_id_ns *id) > if (ns->head->disk) { > nvme_update_disk_info(ns->head->disk, ns, id); > blk_queue_stack_limits(ns->head->disk->queue, ns->queue); > - revalidate_disk(ns->head->disk); > } > #endif >=20 --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --9zSXsLTf0vkW971A Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EABECAB0WIQRPfPO7r0eAhk010v0w5/Bqldv68gUCX3Sw3gAKCRAw5/Bqldv6 8t4DAJ4rcxxp+UnUWIjiAXQB7wbfwWEb5QCePmHmhzP4Yk6dyrSZjnESc5/eNhk= =aSgn -----END PGP SIGNATURE----- --9zSXsLTf0vkW971A--