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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham 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 35465C282CE for ; Tue, 9 Apr 2019 13:13:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 029052084C for ; Tue, 9 Apr 2019 13:13:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727515AbfDINNy (ORCPT ); Tue, 9 Apr 2019 09:13:54 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:34176 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727136AbfDINNx (ORCPT ); Tue, 9 Apr 2019 09:13:53 -0400 Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x39DBcxX089227 for ; Tue, 9 Apr 2019 09:13:53 -0400 Received: from e33.co.us.ibm.com (e33.co.us.ibm.com [32.97.110.151]) by mx0a-001b2d01.pphosted.com with ESMTP id 2rru3ekku9-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 09 Apr 2019 09:13:52 -0400 Received: from localhost by e33.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 9 Apr 2019 14:13:50 +0100 Received: from b03ledav003.gho.boulder.ibm.com (b03ledav003.gho.boulder.ibm.com [9.17.130.234]) by b03cxnp08028.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x39DDnuE32047136 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 9 Apr 2019 13:13:49 GMT Received: from b03ledav003.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B4BA16A047; Tue, 9 Apr 2019 13:13:49 +0000 (GMT) Received: from b03ledav003.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 50B716A04D; Tue, 9 Apr 2019 13:13:49 +0000 (GMT) Received: from [9.56.58.129] (unknown [9.56.58.129]) by b03ledav003.gho.boulder.ibm.com (Postfix) with ESMTP; Tue, 9 Apr 2019 13:13:49 +0000 (GMT) Subject: Re: [PATCH v2 1/1] vfio: Fix WARNING "do not call blocking ops when !TASK_RUNNING" To: kvm@vger.kernel.org, alex.williamson@redhat.com References: <159c2af6cc2fc8ca838cfa7ab9a54e8a1b7507b9.1554315372.git.alifm@linux.ibm.com> From: Farhan Ali Date: Tue, 9 Apr 2019 09:13:48 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <159c2af6cc2fc8ca838cfa7ab9a54e8a1b7507b9.1554315372.git.alifm@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 19040913-0036-0000-0000-00000AA65BE8 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010895; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000284; SDB=6.01186591; UDB=6.00621476; IPR=6.00967351; MB=3.00026361; MTD=3.00000008; XFM=3.00000015; UTC=2019-04-09 13:13:51 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19040913-0037-0000-0000-00004B52E94E Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-04-09_06:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904090084 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 04/03/2019 02:22 PM, Farhan Ali wrote: > 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 accquire 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 articlehttps://lwn.net/Articles/628628/. > > Signed-off-by: Farhan Ali > --- > > I have already tested in my environment and the warning goes > away for me with this patch. But appreciate further testing > and review feedback on the patch. > > Thanks > Farhan > > > ChangeLog > --------- > v1 -> v2 > - Keep the same behavior as before, so the task goes into > TASK_UNINTERRUPTIBLE state after being interrupted once > > --- Hi Alex, Polite ping :) Do you have any other feedback regarding the patch? Thanks Farhan