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 X-Spam-Level: X-Spam-Status: No, score=-8.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BEFE8C31E49 for ; Thu, 13 Jun 2019 16:02:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8A455208CA for ; Thu, 13 Jun 2019 16:02:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560441731; bh=N8ACM1DFYnNts9wdOatsvGPHvKobHRaV8DL0G4MQcZg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=fezzq13Wq0P5AzVtGUEurR9vpX262u6LVeItKDY89S6pHmvsbyQLGOIEqaPYnnE7r T2r5LZ7LMod9rx99x0PRezRAiEkxoTNfZ5doNdNEd4VnxnTRUXkew7sGaDXVSvw2PH zxISqfw3D23wcl3Af+GxEDAKqfqPK4zS0PeaeP7s= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390892AbfFMQB7 (ORCPT ); Thu, 13 Jun 2019 12:01:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:36090 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731411AbfFMIsF (ORCPT ); Thu, 13 Jun 2019 04:48:05 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2B98D2147A; Thu, 13 Jun 2019 08:48:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560415683; bh=N8ACM1DFYnNts9wdOatsvGPHvKobHRaV8DL0G4MQcZg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GBSM7H1NhwJ8rIi2IKItomh9Q8IkYySbeHLlJ5lKBRS7XkDBfrGAQHSD8Ok1dqHP1 gnk/UxFCr+Ek9fE49isKmpV9vc1opUwXyTog9gyGl0DVi5J5Rzk4lXdv/tODqSwq3J 9S644F10QfzqzTP5G8zbcxOTpJosrMfkcYdLc4/M= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Farhan Ali , Alex Williamson , Sasha Levin Subject: [PATCH 5.1 088/155] vfio: Fix WARNING "do not call blocking ops when !TASK_RUNNING" Date: Thu, 13 Jun 2019 10:33:20 +0200 Message-Id: <20190613075658.024902313@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190613075652.691765927@linuxfoundation.org> References: <20190613075652.691765927@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [ Upstream commit 41be3e2618174fdf3361e49e64f2bf530f40c6b0 ] vfio_dev_present() which is the condition to wait_event_interruptible_timeout(), will call vfio_group_get_device and try to acquire the mutex group->device_lock. wait_event_interruptible_timeout() will set the state of the current task to TASK_INTERRUPTIBLE, before doing the condition check. This means that we will try to acquire the mutex while already in a sleeping state. The scheduler warns us by giving the following warning: [ 4050.264464] ------------[ cut here ]------------ [ 4050.264508] do not call blocking ops when !TASK_RUNNING; state=1 set at [<00000000b33c00e2>] prepare_to_wait_event+0x14a/0x188 [ 4050.264529] WARNING: CPU: 12 PID: 35924 at kernel/sched/core.c:6112 __might_sleep+0x76/0x90 .... 4050.264756] Call Trace: [ 4050.264765] ([<000000000017bbaa>] __might_sleep+0x72/0x90) [ 4050.264774] [<0000000000b97edc>] __mutex_lock+0x44/0x8c0 [ 4050.264782] [<0000000000b9878a>] mutex_lock_nested+0x32/0x40 [ 4050.264793] [<000003ff800d7abe>] vfio_group_get_device+0x36/0xa8 [vfio] [ 4050.264803] [<000003ff800d87c0>] vfio_del_group_dev+0x238/0x378 [vfio] [ 4050.264813] [<000003ff8015f67c>] mdev_remove+0x3c/0x68 [mdev] [ 4050.264825] [<00000000008e01b0>] device_release_driver_internal+0x168/0x268 [ 4050.264834] [<00000000008de692>] bus_remove_device+0x162/0x190 [ 4050.264843] [<00000000008daf42>] device_del+0x1e2/0x368 [ 4050.264851] [<00000000008db12c>] device_unregister+0x64/0x88 [ 4050.264862] [<000003ff8015ed84>] mdev_device_remove+0xec/0x130 [mdev] [ 4050.264872] [<000003ff8015f074>] remove_store+0x6c/0xa8 [mdev] [ 4050.264881] [<000000000046f494>] kernfs_fop_write+0x14c/0x1f8 [ 4050.264890] [<00000000003c1530>] __vfs_write+0x38/0x1a8 [ 4050.264899] [<00000000003c187c>] vfs_write+0xb4/0x198 [ 4050.264908] [<00000000003c1af2>] ksys_write+0x5a/0xb0 [ 4050.264916] [<0000000000b9e270>] system_call+0xdc/0x2d8 [ 4050.264925] 4 locks held by sh/35924: [ 4050.264933] #0: 000000001ef90325 (sb_writers#4){.+.+}, at: vfs_write+0x9e/0x198 [ 4050.264948] #1: 000000005c1ab0b3 (&of->mutex){+.+.}, at: kernfs_fop_write+0x1cc/0x1f8 [ 4050.264963] #2: 0000000034831ab8 (kn->count#297){++++}, at: kernfs_remove_self+0x12e/0x150 [ 4050.264979] #3: 00000000e152484f (&dev->mutex){....}, at: device_release_driver_internal+0x5c/0x268 [ 4050.264993] Last Breaking-Event-Address: [ 4050.265002] [<000000000017bbaa>] __might_sleep+0x72/0x90 [ 4050.265010] irq event stamp: 7039 [ 4050.265020] hardirqs last enabled at (7047): [<00000000001cee7a>] console_unlock+0x6d2/0x740 [ 4050.265029] hardirqs last disabled at (7054): [<00000000001ce87e>] console_unlock+0xd6/0x740 [ 4050.265040] softirqs last enabled at (6416): [<0000000000b8fe26>] __udelay+0xb6/0x100 [ 4050.265049] softirqs last disabled at (6415): [<0000000000b8fe06>] __udelay+0x96/0x100 [ 4050.265057] ---[ end trace d04a07d39d99a9f9 ]--- Let's fix this as described in the article https://lwn.net/Articles/628628/. Signed-off-by: Farhan Ali [remove now redundant vfio_dev_present()] Signed-off-by: Alex Williamson Signed-off-by: Sasha Levin --- drivers/vfio/vfio.c | 30 ++++++++++-------------------- 1 file changed, 10 insertions(+), 20 deletions(-) diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index a3030cdf3c18..aa0e14d25ac3 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -34,6 +34,7 @@ #include #include #include +#include #define DRIVER_VERSION "0.3" #define DRIVER_AUTHOR "Alex Williamson " @@ -904,30 +905,17 @@ void *vfio_device_data(struct vfio_device *device) } EXPORT_SYMBOL_GPL(vfio_device_data); -/* Given a referenced group, check if it contains the device */ -static bool vfio_dev_present(struct vfio_group *group, struct device *dev) -{ - struct vfio_device *device; - - device = vfio_group_get_device(group, dev); - if (!device) - return false; - - vfio_device_put(device); - return true; -} - /* * Decrement the device reference count and wait for the device to be * removed. Open file descriptors for the device... */ void *vfio_del_group_dev(struct device *dev) { + DEFINE_WAIT_FUNC(wait, woken_wake_function); struct vfio_device *device = dev_get_drvdata(dev); struct vfio_group *group = device->group; void *device_data = device->device_data; struct vfio_unbound_dev *unbound; unsigned int i = 0; - long ret; bool interrupted = false; /* @@ -964,6 +952,8 @@ void *vfio_del_group_dev(struct device *dev) * interval with counter to allow the driver to take escalating * measures to release the device if it has the ability to do so. */ + add_wait_queue(&vfio.release_q, &wait); + do { device = vfio_group_get_device(group, dev); if (!device) @@ -975,12 +965,10 @@ void *vfio_del_group_dev(struct device *dev) vfio_device_put(device); if (interrupted) { - ret = wait_event_timeout(vfio.release_q, - !vfio_dev_present(group, dev), HZ * 10); + wait_woken(&wait, TASK_UNINTERRUPTIBLE, HZ * 10); } else { - ret = wait_event_interruptible_timeout(vfio.release_q, - !vfio_dev_present(group, dev), HZ * 10); - if (ret == -ERESTARTSYS) { + wait_woken(&wait, TASK_INTERRUPTIBLE, HZ * 10); + if (signal_pending(current)) { interrupted = true; dev_warn(dev, "Device is currently in use, task" @@ -989,8 +977,10 @@ void *vfio_del_group_dev(struct device *dev) current->comm, task_pid_nr(current)); } } - } while (ret <= 0); + } while (1); + + remove_wait_queue(&vfio.release_q, &wait); /* * In order to support multiple devices per group, devices can be * plucked from the group while other devices in the group are still -- 2.20.1