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 0F9D1CCA47C for ; Tue, 7 Jun 2022 18:19:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351442AbiFGSSw (ORCPT ); Tue, 7 Jun 2022 14:18:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351925AbiFGSQs (ORCPT ); Tue, 7 Jun 2022 14:16:48 -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 DC8A31203D1; Tue, 7 Jun 2022 10:50:08 -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 3F8DEB82348; Tue, 7 Jun 2022 17:50:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AD40EC385A5; Tue, 7 Jun 2022 17:50:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1654624206; bh=VQ5EhX/1Y2JAck2MGUrUMm+ylhKEXTYBnwnSHm3qpQc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1QlykbC+zdOdaRwg8iFlMVPxtei5pQkKmUlyas4YyD0McKgVfkuZwiZHuXA00ceZi gXTasFhPoiGC616EBsTJZHb/1OzH6Amo8PQW0zkQ1zkK92f+h1upahNhloXUBVzS82 +ltWebLBXC66Z2NwYnAvocEaWF4FQzHSS6+LEvHY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Khazhismel Kumykov , Amir Goldstein , Jan Kara , Sasha Levin Subject: [PATCH 5.15 243/667] fsnotify: fix wrong lockdep annotations Date: Tue, 7 Jun 2022 18:58:28 +0200 Message-Id: <20220607164942.071751319@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220607164934.766888869@linuxfoundation.org> References: <20220607164934.766888869@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Amir Goldstein [ Upstream commit 623af4f538b5df9b416e1b82f720af7371b4c771 ] Commit 6960b0d909cd ("fsnotify: change locking order") changed some of the mark_mutex locks in direct reclaim path to use: mutex_lock_nested(&group->mark_mutex, SINGLE_DEPTH_NESTING); This change is explained: "...It uses nested locking to avoid deadlock in case we do the final iput() on an inode which still holds marks and thus would take the mutex again when calling fsnotify_inode_delete() in destroy_inode()." The problem is that the mutex_lock_nested() is not a nested lock at all. In fact, it has the opposite effect of preventing lockdep from warning about a very possible deadlock. Due to these wrong annotations, a deadlock that was introduced with nfsd filecache in kernel v5.4 went unnoticed in v5.4.y for over two years until it was reported recently by Khazhismel Kumykov, only to find out that the deadlock was already fixed in kernel v5.5. Fix the wrong lockdep annotations. Cc: Khazhismel Kumykov Fixes: 6960b0d909cd ("fsnotify: change locking order") Link: https://lore.kernel.org/r/20220321112310.vpr7oxro2xkz5llh@quack3.lan/ Link: https://lore.kernel.org/r/20220422120327.3459282-4-amir73il@gmail.com Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara Signed-off-by: Sasha Levin --- fs/notify/mark.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/notify/mark.c b/fs/notify/mark.c index fa1d99101f89..bea106fac090 100644 --- a/fs/notify/mark.c +++ b/fs/notify/mark.c @@ -452,7 +452,7 @@ void fsnotify_free_mark(struct fsnotify_mark *mark) void fsnotify_destroy_mark(struct fsnotify_mark *mark, struct fsnotify_group *group) { - mutex_lock_nested(&group->mark_mutex, SINGLE_DEPTH_NESTING); + mutex_lock(&group->mark_mutex); fsnotify_detach_mark(mark); mutex_unlock(&group->mark_mutex); fsnotify_free_mark(mark); @@ -767,7 +767,7 @@ void fsnotify_clear_marks_by_group(struct fsnotify_group *group, * move marks to free to to_free list in one go and then free marks in * to_free list one by one. */ - mutex_lock_nested(&group->mark_mutex, SINGLE_DEPTH_NESTING); + mutex_lock(&group->mark_mutex); list_for_each_entry_safe(mark, lmark, &group->marks_list, g_list) { if ((1U << mark->connector->type) & type_mask) list_move(&mark->g_list, &to_free); @@ -776,7 +776,7 @@ void fsnotify_clear_marks_by_group(struct fsnotify_group *group, clear: while (1) { - mutex_lock_nested(&group->mark_mutex, SINGLE_DEPTH_NESTING); + mutex_lock(&group->mark_mutex); if (list_empty(head)) { mutex_unlock(&group->mark_mutex); break; -- 2.35.1