From nobody Tue Dec 16 16:37:42 2025 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 EEEEDC32772 for ; Fri, 19 Aug 2022 16:22:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352404AbiHSQW2 (ORCPT ); Fri, 19 Aug 2022 12:22:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53058 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352596AbiHSQRP (ORCPT ); Fri, 19 Aug 2022 12:17:15 -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 71D1E116EED; Fri, 19 Aug 2022 09:00:23 -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 32BDBB827F8; Fri, 19 Aug 2022 16:00:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 912A7C433D6; Fri, 19 Aug 2022 16:00:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1660924820; bh=ChWf+LtxRb24AG++lacK+sYcVfg3nX7V4e/awgBbszs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fXnITut83ZNogiYMjunl+7RuOCzuVjVGeQMm7OsiP+0ruEuZFjeyt9jIhVV50cL1/ T7pQJIBysbHZUx2O2W5bXqRqr3J8t1p/KM0QPg1OdGH5k1w4ZIEKA7Ul7/JwQ83MLm li0S6bUaFDNf9dflPaRgOZDdnHfJZsgAski0Nkb4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zhang Wensheng , Sasha Levin Subject: [PATCH 5.10 293/545] driver core: fix potential deadlock in __driver_attach Date: Fri, 19 Aug 2022 17:41:03 +0200 Message-Id: <20220819153842.447940623@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220819153829.135562864@linuxfoundation.org> References: <20220819153829.135562864@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Zhang Wensheng [ Upstream commit 70fe758352cafdee72a7b13bf9db065f9613ced8 ] In __driver_attach function, There are also AA deadlock problem, like the commit b232b02bf3c2 ("driver core: fix deadlock in __device_attach"). stack like commit b232b02bf3c2 ("driver core: fix deadlock in __device_attach"). list below: In __driver_attach function, The lock holding logic is as follows: ... __driver_attach if (driver_allows_async_probing(drv)) device_lock(dev) // get lock dev async_schedule_dev(__driver_attach_async_helper, dev); // func async_schedule_node async_schedule_node_domain(func) entry =3D kzalloc(sizeof(struct async_entry), GFP_ATOMIC); /* when fail or work limit, sync to execute func, but __driver_attach_async_helper will get lock dev as will, which will lead to A-A deadlock. */ if (!entry || atomic_read(&entry_count) > MAX_WORK) { func; else queue_work_node(node, system_unbound_wq, &entry->work) device_unlock(dev) As above show, when it is allowed to do async probes, because of out of memory or work limit, async work is not be allowed, to do sync execute instead. it will lead to A-A deadlock because of __driver_attach_async_helper getting lock dev. Reproduce: and it can be reproduce by make the condition (if (!entry || atomic_read(&entry_count) > MAX_WORK)) untenable, like below: [ 370.785650] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 370.787154] task:swapper/0 state:D stack: 0 pid: 1 ppid: 0 flags:0x00004000 [ 370.788865] Call Trace: [ 370.789374] [ 370.789841] __schedule+0x482/0x1050 [ 370.790613] schedule+0x92/0x1a0 [ 370.791290] schedule_preempt_disabled+0x2c/0x50 [ 370.792256] __mutex_lock.isra.0+0x757/0xec0 [ 370.793158] __mutex_lock_slowpath+0x1f/0x30 [ 370.794079] mutex_lock+0x50/0x60 [ 370.794795] __device_driver_lock+0x2f/0x70 [ 370.795677] ? driver_probe_device+0xd0/0xd0 [ 370.796576] __driver_attach_async_helper+0x1d/0xd0 [ 370.797318] ? driver_probe_device+0xd0/0xd0 [ 370.797957] async_schedule_node_domain+0xa5/0xc0 [ 370.798652] async_schedule_node+0x19/0x30 [ 370.799243] __driver_attach+0x246/0x290 [ 370.799828] ? driver_allows_async_probing+0xa0/0xa0 [ 370.800548] bus_for_each_dev+0x9d/0x130 [ 370.801132] driver_attach+0x22/0x30 [ 370.801666] bus_add_driver+0x290/0x340 [ 370.802246] driver_register+0x88/0x140 [ 370.802817] ? virtio_scsi_init+0x116/0x116 [ 370.803425] scsi_register_driver+0x1a/0x30 [ 370.804057] init_sd+0x184/0x226 [ 370.804533] do_one_initcall+0x71/0x3a0 [ 370.805107] kernel_init_freeable+0x39a/0x43a [ 370.805759] ? rest_init+0x150/0x150 [ 370.806283] kernel_init+0x26/0x230 [ 370.806799] ret_from_fork+0x1f/0x30 To fix the deadlock, move the async_schedule_dev outside device_lock, as we can see, in async_schedule_node_domain, the parameter of queue_work_node is system_unbound_wq, so it can accept concurrent operations. which will also not change the code logic, and will not lead to deadlock. Fixes: ef0ff68351be ("driver core: Probe devices asynchronously instead of = the driver") Signed-off-by: Zhang Wensheng Link: https://lore.kernel.org/r/20220622074327.497102-1-zhangwensheng5@huaw= ei.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/base/dd.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/base/dd.c b/drivers/base/dd.c index f9d9f1ad9215..b5441741274b 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -1056,6 +1056,7 @@ static void __driver_attach_async_helper(void *_dev, = async_cookie_t cookie) static int __driver_attach(struct device *dev, void *data) { struct device_driver *drv =3D data; + bool async =3D false; int ret; =20 /* @@ -1093,9 +1094,11 @@ static int __driver_attach(struct device *dev, void = *data) if (!dev->driver) { get_device(dev); dev->p->async_driver =3D drv; - async_schedule_dev(__driver_attach_async_helper, dev); + async =3D true; } device_unlock(dev); + if (async) + async_schedule_dev(__driver_attach_async_helper, dev); return 0; } =20 --=20 2.35.1