From patchwork Wed Dec 13 21:33:09 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Moyer X-Patchwork-Id: 10110949 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id CBE5360327 for ; Wed, 13 Dec 2017 21:33:13 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BD51328FB6 for ; Wed, 13 Dec 2017 21:33:13 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B1F7B28FBF; Wed, 13 Dec 2017 21:33:13 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.9 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 4AB7128FB6 for ; Wed, 13 Dec 2017 21:33:12 +0000 (UTC) Received: from [127.0.0.1] (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 3168E2034B9C6; Wed, 13 Dec 2017 13:28:32 -0800 (PST) X-Original-To: linux-nvdimm@lists.01.org Delivered-To: linux-nvdimm@lists.01.org Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=209.132.183.28; helo=mx1.redhat.com; envelope-from=jmoyer@redhat.com; receiver=linux-nvdimm@lists.01.org Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id C184B2034B9C3 for ; Wed, 13 Dec 2017 13:28:31 -0800 (PST) Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0FB1E81DE6; Wed, 13 Dec 2017 21:33:11 +0000 (UTC) Received: from segfault.boston.devel.redhat.com (segfault.boston.devel.redhat.com [10.19.60.26]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 962E97BFF5; Wed, 13 Dec 2017 21:33:10 +0000 (UTC) From: Jeff Moyer To: dan.j.williams@intel.com, vishal.l.verma@intel.com Subject: [patch] btt: fix uninitialized err_lock X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Wed, 13 Dec 2017 16:33:09 -0500 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Wed, 13 Dec 2017 21:33:11 +0000 (UTC) X-BeenThere: linux-nvdimm@lists.01.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: "Linux-nvdimm developer list." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-nvdimm@lists.01.org Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" X-Virus-Scanned: ClamAV using ClamSMTP Hi, When a sector mode namespace is initially created, the arena's err_lock is not initialized. If, on the other hand, the namespace already exists, the mutex is initialized. To fix the issue, I moved the mutex initialization into the arena_alloc, which is called by both discover_arenas and create_arenas. This was discovered on an older kernel where mutex_trylock checks the count to determine whether the lock is held. Because the data structure is kzalloc-d, that count was 0 (held), and I/O to the device would hang forever waiting for the lock to be released (see btt_write_pg, for example). Current kernels have a different mutex implementation that checks for a non-null owner, and so this doesn't show up as a problem. If that lock were ever contended, it might cause issues, but you'd have to be really unlucky, I think. Signed-off-by: Jeff Moyer Reviewed-by: Vishal Verma diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c index e949e33..5860f99 100644 --- a/drivers/nvdimm/btt.c +++ b/drivers/nvdimm/btt.c @@ -630,6 +630,7 @@ static struct arena_info *alloc_arena(struct btt *btt, size_t size, return NULL; arena->nd_btt = btt->nd_btt; arena->sector_size = btt->sector_size; + mutex_init(&arena->err_lock); if (!size) return arena; @@ -758,7 +759,6 @@ static int discover_arenas(struct btt *btt) arena->external_lba_start = cur_nlba; parse_arena_meta(arena, super, cur_off); - mutex_init(&arena->err_lock); ret = btt_freelist_init(arena); if (ret) goto out;