From patchwork Fri Mar 4 07:06:41 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Byungchul Park X-Patchwork-Id: 12768617 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 54E5DC433EF for ; Fri, 4 Mar 2022 07:08:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238913AbiCDHJJ (ORCPT ); Fri, 4 Mar 2022 02:09:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39350 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238775AbiCDHIv (ORCPT ); Fri, 4 Mar 2022 02:08:51 -0500 Received: from lgeamrelo11.lge.com (lgeamrelo13.lge.com [156.147.23.53]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 50D12192C9F for ; Thu, 3 Mar 2022 23:07:13 -0800 (PST) Received: from unknown (HELO lgemrelse6q.lge.com) (156.147.1.121) by 156.147.23.53 with ESMTP; 4 Mar 2022 16:07:09 +0900 X-Original-SENDERIP: 156.147.1.121 X-Original-MAILFROM: byungchul.park@lge.com Received: from unknown (HELO localhost.localdomain) (10.177.244.38) by 156.147.1.121 with ESMTP; 4 Mar 2022 16:07:09 +0900 X-Original-SENDERIP: 10.177.244.38 X-Original-MAILFROM: byungchul.park@lge.com From: Byungchul Park To: torvalds@linux-foundation.org Cc: damien.lemoal@opensource.wdc.com, linux-ide@vger.kernel.org, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, mingo@redhat.com, linux-kernel@vger.kernel.org, peterz@infradead.org, will@kernel.org, tglx@linutronix.de, rostedt@goodmis.org, joel@joelfernandes.org, sashal@kernel.org, daniel.vetter@ffwll.ch, chris@chris-wilson.co.uk, duyuyang@gmail.com, johannes.berg@intel.com, tj@kernel.org, tytso@mit.edu, willy@infradead.org, david@fromorbit.com, amir73il@gmail.com, bfields@fieldses.org, gregkh@linuxfoundation.org, kernel-team@lge.com, linux-mm@kvack.org, akpm@linux-foundation.org, mhocko@kernel.org, minchan@kernel.org, hannes@cmpxchg.org, vdavydov.dev@gmail.com, sj@kernel.org, jglisse@redhat.com, dennis@kernel.org, cl@linux.com, penberg@kernel.org, rientjes@google.com, vbabka@suse.cz, ngupta@vflare.org, linux-block@vger.kernel.org, paolo.valente@linaro.org, josef@toxicpanda.com, linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk, jack@suse.cz, jack@suse.com, jlayton@kernel.org, dan.j.williams@intel.com, hch@infradead.org, djwong@kernel.org, dri-devel@lists.freedesktop.org, airlied@linux.ie, rodrigosiqueiramelo@gmail.com, melissa.srw@gmail.com, hamohammed.sa@gmail.com Subject: [PATCH v4 22/24] dept: Don't create dependencies between different depths in any case Date: Fri, 4 Mar 2022 16:06:41 +0900 Message-Id: <1646377603-19730-23-git-send-email-byungchul.park@lge.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1646377603-19730-1-git-send-email-byungchul.park@lge.com> References: <1646377603-19730-1-git-send-email-byungchul.park@lge.com> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Dept already prevents creating dependencies between different depths of the class indicated by *_lock_nested() when the lock acquisitions happen consecutively. lock A0 with depth lock_nested A1 with depth + 1 ... unlock A1 unlock A0 Dept does not create A0 -> A1 dependency in this case, either. However, once another class cut in, the code becomes problematic. When Dept tries to create real dependencies, it does not only create real ones but also wrong ones between different depths of the class. lock A0 with depth lock B lock_nested A1 with depth + 1 ... unlock A1 unlock B unlock A0 Even in this case, Dept should not create A0 -> A1 dependency. So let Dept not create wrong dependencies between different depths of the class in any case. Reported-by: 42.hyeyoo@gmail.com Signed-off-by: Byungchul Park Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> --- kernel/dependency/dept.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) diff --git a/kernel/dependency/dept.c b/kernel/dependency/dept.c index 5d4efc3..cc1b3a3 100644 --- a/kernel/dependency/dept.c +++ b/kernel/dependency/dept.c @@ -1458,14 +1458,7 @@ static void add_wait(struct dept_class *c, unsigned long ip, eh = dt->ecxt_held + i; if (eh->ecxt->class != c || eh->nest == ne) - break; - } - - for (; i >= 0; i--) { - struct dept_ecxt_held *eh; - - eh = dt->ecxt_held + i; - add_dep(eh->ecxt, w); + add_dep(eh->ecxt, w); } if (!wait_consumed(w) && !rich_stack) {