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 4C49FC433FE for ; Thu, 17 Nov 2022 11:54:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234938AbiKQLye (ORCPT ); Thu, 17 Nov 2022 06:54:34 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56494 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234051AbiKQLyb (ORCPT ); Thu, 17 Nov 2022 06:54:31 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 107EF632A for ; Thu, 17 Nov 2022 03:54:30 -0800 (PST) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1668686069; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=LqTjUyk61qo670ba2YgIwexSBuri4lwqzxTw2esfEJU=; b=EGB07lko/R1OsOyXFrtCbq/6QA1irKQNX6XMfraI0MtCVFCvqc4dcBWx4gqx9VmeCRM7JD 1B1oQ0ypbttO7J0VgoMWKbBOoK38k88OA2YTqku0AYycxBC+ucMPnVsnh6cVYfKN7gMEGp S/8s75yjN2wBBycEryl0TgYFp5mWG5zh74/4od4CpRk3PtrZIvd/6RWf2BfK5C9OGaUn2r m/DRNy0eIrl7797NWqDYbL0h7SX+QYvnXIaehHRrx3fymTMx5XW+Nsdcyz4v8MnvdKuvCs DB8pEAiE3bBvyB3D0P1S9AKX6tmsUHpBz+1eiYxPpK1r0xKRx7XcUnLi0MLCRA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1668686069; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=LqTjUyk61qo670ba2YgIwexSBuri4lwqzxTw2esfEJU=; b=Ua0y898NOpzh5FCKfEFs8Fhj1ZvuNsqbNoRKaCzt4bIsXWUe2lPcJZPxvT53dH/nqPtBNT rL/8vW6aZVi+LPAg== To: Hillf Danton Cc: syzbot , linux-kernel@vger.kernel.org, pbonzini@redhat.com, syzkaller-bugs@googlegroups.com, Steven Rostedt , Marcel Holtmann , Luiz Augusto von Dentz Subject: Re: [syzbot] WARNING in call_timer_fn In-Reply-To: <20221117024511.3606-1-hdanton@sina.com> References: <0000000000009d5daa05ed9815fa@google.com> <20221117024511.3606-1-hdanton@sina.com> Date: Thu, 17 Nov 2022 12:54:28 +0100 Message-ID: <87fsehn6dn.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 17 2022 at 10:45, Hillf Danton wrote: > On 16 Nov 2022 19:29:27 +0100 Thomas Gleixner >> > > I doubt your fix helps in the domain of workqueue in general, and in this > report if it is delayed work that triggered the warning. Indeed. I misread the backtrace and my brain connected the wrong dots here. It's a different bluethooth hickup. > --- x/net/bluetooth/hci_sync.c > +++ y/net/bluetooth/hci_sync.c > @@ -4806,6 +4806,7 @@ int hci_dev_close_sync(struct hci_dev *h > /* Avoid potential lockdep warnings from the *_flush() calls by > * ensuring the workqueue is empty up front. > */ > + cancel_delayed_work_sync(&hdev->cmd_timer); > drain_workqueue(hdev->workqueue); The work has been canceled already before in the same function and there are some more delayed works which can trigger this. So no, this whole close_sync() function is prone to teardown races and just slapping a single cancel here without deeper analysis does not cut it. Thanks, tglx