From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [85.220.165.71]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2954A7A for ; Thu, 16 Jun 2022 10:38:27 +0000 (UTC) Received: from ptz.office.stw.pengutronix.de ([2a0a:edc0:0:900:1d::77] helo=[127.0.0.1]) by metis.ext.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1o1mtL-0006Uh-On; Thu, 16 Jun 2022 12:38:23 +0200 Message-ID: Date: Thu, 16 Jun 2022 12:38:21 +0200 Precedence: bulk X-Mailing-List: regressions@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 From: Ahmad Fatoum Subject: Re: [BUG] BLE device unpairing triggers kernel panic To: Luiz Augusto von Dentz Cc: "linux-bluetooth@vger.kernel.org" , Marcel Holtmann , "regressions@lists.linux.dev" , Pengutronix Kernel Team References: <8d5c4724-d511-39b1-21d7-116c91cada45@pengutronix.de> Content-Language: en-US In-Reply-To: <8d5c4724-d511-39b1-21d7-116c91cada45@pengutronix.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2a0a:edc0:0:900:1d::77 X-SA-Exim-Mail-From: a.fatoum@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: regressions@lists.linux.dev Hello Luiz, On 16.05.22 18:37, Ahmad Fatoum wrote: >>>> - Commit a56a1138cbd8 ("Bluetooth: hci_sync: Fix not using conn_timeout") >>>> fixes, despite the title, what event is waited on. First Pairing works now, >>>> but the second pairing times out and crashes the kernel: >>>> >>>> [ 84.191684] Bluetooth: hci0: Opcode 0x200d failed: -110 >>>> [ 84.230478] Bluetooth: hci0: request failed to create LE connection: err -110 >>>> [ 84.237690] Unable to handle kernel read from unreadable memory at virtual address 0000000000000ca8 >> >> That said the error -110 mean -ETIMEDOUT > > Yes, this issue remains still. I feel better about my revert > knowing that the crash is fixed, but I'd like this regression > here fixed upstream as well. I'll try to collect some more > information and report back. I've now found time to revisit this and sprinkle around some extra logging. This is the initial pairing that works: Bluetooth: entered hci_le_create_conn_sync() Bluetooth: hci0: opcode 0x200d plen 25 Bluetooth: hci0: event 0x0f (sent = 0x0a) Bluetooth: hci0: BT: opcode 0x200d (sent: 0x0a) Bluetooth: hci0: event 0x3e (sent = 0x0a) Bluetooth: hci0: BT: subevent 0x0a (sent 0x0a) Bluetooth: entered hci_le_meta_evt(event=0x0a) completion clause I unpaired on device side and then retried pairing: Bluetooth: entered hci_le_create_conn_sync() Bluetooth: hci0: opcode 0x200d plen 25 Bluetooth: hci0: event 0x0f (sent = 0x0a) Bluetooth: hci0: BT: opcode 0x200d (sent: 0x0a) Bluetooth: entered hci_abort_conn() Bluetooth: hci0: opcode hci_req_add_ev 0x200e Bluetooth: hci0: event 0x0e (sent = 0x00) Bluetooth: hci0: event 0x3e (sent = 0x00) Bluetooth: hci0: BT: subevent 0x0a (sent 0x00) Bluetooth: __hci_cmd_sync_sk pending (event = 0x0a status=1, err=-110) Bluetooth: hci0: Opcode 0x200d failed: -110 Bluetooth: hci0: opcode 0x2006 plen 15 Bluetooth: hci0: event 0x0e (sent = 0x00) Bluetooth: hci0: opcode 0x200a plen 1 Bluetooth: hci0: event 0x0e (sent = 0x00) Bluetooth: hci0: request failed to create LE connection: err -110 But now it times out as reported. It looks like the intermittent hci_abort_conn() is at fault here. My theory is that replacing hci->sent_cmd is the problem here, as other events can't be matched anymore. We've been deploying the revert for a while now and I just posted it to the mailing list[1]. There have been other reports of this issue with different hardware too and fixing sent_cmd would likely be too complicated/time intensive for me. I am happy to test future patches that fix this properly though. [1]: https://lore.kernel.org/linux-bluetooth/20220616092418.738877-1-a.fatoum@pengutronix.de/T/#t Cheers, Ahmad > > Cheers, > Ahmad > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |