From nobody Mon Feb 9 04:59:56 2026 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 E1C6FC7EE23 for ; Wed, 7 Jun 2023 10:19:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239645AbjFGKTZ (ORCPT ); Wed, 7 Jun 2023 06:19:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44162 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239569AbjFGKTO (ORCPT ); Wed, 7 Jun 2023 06:19:14 -0400 Received: from www262.sakura.ne.jp (www262.sakura.ne.jp [202.181.97.72]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 29C2F1FC2 for ; Wed, 7 Jun 2023 03:19:06 -0700 (PDT) Received: from fsav414.sakura.ne.jp (fsav414.sakura.ne.jp [133.242.250.113]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 357AJ45u053811; Wed, 7 Jun 2023 19:19:04 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav414.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav414.sakura.ne.jp); Wed, 07 Jun 2023 19:19:04 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav414.sakura.ne.jp) Received: from [192.168.1.6] (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 357AJ49C053807 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NO); Wed, 7 Jun 2023 19:19:04 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Message-ID: <492fe2ae-5141-d548-ebd5-62f5fe2e57f7@I-love.SAKURA.ne.jp> Date: Wed, 7 Jun 2023 19:19:02 +0900 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.11.2 Subject: [PATCH v2] debugobjects: recheck debug_objects_enabled before reporting Content-Language: en-US To: Thomas Gleixner , syzbot , syzkaller-bugs@googlegroups.com Cc: linux-kernel@vger.kernel.org, Stephen Boyd , Andrew Morton , Peter Zijlstra , wuchi References: <0000000000003a2f8505fcd5f06b@google.com> <1af29817-4698-c5ac-cf63-0dad289e740f@I-love.SAKURA.ne.jp> <871qiokyma.ffs@tglx> From: Tetsuo Handa In-Reply-To: <871qiokyma.ffs@tglx> Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" syzbot is reporting false positive ODEBUG message immediately after ODEBUG was disabled due to OOM. We should recheck debug_objects_enabled before reporting. [ 1062.309646][T22911] ODEBUG: Out of memory. ODEBUG disabled [ 1062.886755][ T5171] ------------[ cut here ]------------ [ 1062.892770][ T5171] ODEBUG: assert_init not available (active state 0)= object: ffffc900056afb20 object type: timer_list hint: process_timeout+0x0= /0x40 CPU 0 [ T5171] CPU 1 [T22911] -------------- -------------- debug_object_assert_init() { if (!debug_objects_enabled) return; db =3D get_bucket((unsigned long) addr); // Finds a bucket, but... lookup_object_or_alloc() { debug_objects_enabled =3D 0; return NULL; } debug_objects_oom() { pr_warn("Out of memory. ODEBUG disabled\n= "); // all buckets get emptied here, and } lookup_object_or_alloc(addr, db, descr, false, true) { // this bucket is already empty. return ERR_PTR(-ENOENT); } // Emits false positive warning. debug_print_object(&o, "assert_init"); } Reported-by: syzbot Closes: https://syzkaller.appspot.com/bug?extid=3D7937ba6a50bdd00fffdf Suggested-by: Thomas Gleixner Signed-off-by: Tetsuo Handa --- Changes in v2: No need to turn off debug_objects_enabled from debug_objects_oom(). lib/debugobjects.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/lib/debugobjects.c b/lib/debugobjects.c index 984985c39c9b..ab3bbcb78471 100644 --- a/lib/debugobjects.c +++ b/lib/debugobjects.c @@ -498,6 +498,15 @@ static void debug_print_object(struct debug_obj *obj, = char *msg) const struct debug_obj_descr *descr =3D obj->descr; static int limit; =20 + /* + * Don't report if lookup_object_or_alloc() by the current thread + * failed because lookup_object_or_alloc()/debug_objects_oom() by + * concurrent thread turned off debug_objects_enabled and cleared + * the hash buckets. + */ + if (!debug_objects_enabled) + return; + if (limit < 5 && descr !=3D descr_test) { void *hint =3D descr->debug_hint ? descr->debug_hint(obj->object) : NULL; --=20 2.18.4