[{"id":1731121,"web_url":"http://patchwork.ozlabs.org/comment/1731121/","msgid":"<5b85a365-faa1-3987-9b6b-270399c30686@kernel.dk>","date":"2017-07-27T16:26:29","subject":"Re: blk_mq_sched_insert_request: inconsistent {SOFTIRQ-ON-W} ->\n\t{IN-SOFTIRQ-W} usage","submitter":{"id":4515,"url":"http://patchwork.ozlabs.org/api/people/4515/","name":"Jens Axboe","email":"axboe@kernel.dk"},"content":"On 07/27/2017 08:47 AM, Bart Van Assche wrote:\n> On Thu, 2017-07-27 at 08:02 -0600, Jens Axboe wrote:\n>> The bug looks like SCSI running the queue inline from IRQ\n>> context, that's not a good idea. Can you confirm the below works for\n>> you?\n>>\n>>\n>> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c\n>> index f6097b89d5d3..78740ebf966c 100644\n>> --- a/drivers/scsi/scsi_lib.c\n>> +++ b/drivers/scsi/scsi_lib.c\n>> @@ -497,7 +497,7 @@ static void scsi_run_queue(struct request_queue *q)\n>> \t\tscsi_starved_list_run(sdev->host);\n>> \n>> \tif (q->mq_ops)\n>> -\t\tblk_mq_run_hw_queues(q, false);\n>> +\t\tblk_mq_run_hw_queues(q, true);\n>> \telse\n>> \t\tblk_run_queue(q);\n>> }\n> \n> Hello Jens,\n> \n> scsi_run_queue() works fine if no scheduler is configured. Additionally, that\n> code predates the introduction of blk-mq I/O schedulers. I think it is\n> nontrivial for block driver authors to figure out that a queue has to be run\n> from process context if a scheduler has been configured that does not support\n> to be run from interrupt context.\n\nNo it doesn't, you could never run the queue from interrupt context with\nasync == false. So I don't think that's confusing at all, you should\nalways be aware of the context.\n\n> How about adding WARN_ON_ONCE(in_interrupt()) to\n> blk_mq_start_hw_queue() or replacing the above patch by the following:\n\nNo, I hate having dependencies like that, because they always just catch\none of them. Looks like the IPR path that hits this should just offload\nto a workqueue or similar, you don't have to make any scsi_run_queue()\nasync.","headers":{"Return-Path":"","X-Original-To":["patchwork-incoming@ozlabs.org","linuxppc-dev@lists.ozlabs.org"],"Delivered-To":["patchwork-incoming@ozlabs.org","linuxppc-dev@lists.ozlabs.org"],"Received":["from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3])\n\t(using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby ozlabs.org (Postfix) with ESMTPS id 3xJHTT1lqrz9rxm\n\tfor ;\n\tFri, 28 Jul 2017 02:28:13 +1000 (AEST)","from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3])\n\tby lists.ozlabs.org (Postfix) with ESMTP id 3xJHTT0dXnzDrKs\n\tfor ;\n\tFri, 28 Jul 2017 02:28:13 +1000 (AEST)","from mail-it0-x22b.google.com (mail-it0-x22b.google.com\n\t[IPv6:2607:f8b0:4001:c0b::22b])\n\t(using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128\n\tbits)) (No client certificate requested)\n\tby lists.ozlabs.org (Postfix) with ESMTPS id 3xJHRZ0VgBzDrGp\n\tfor ;\n\tFri, 28 Jul 2017 02:26:33 +1000 (AEST)","by mail-it0-x22b.google.com with SMTP id h199so85148960ith.0\n\tfor ;\n\tThu, 27 Jul 2017 09:26:33 -0700 (PDT)","from [192.168.1.154] ([216.160.245.98])\n\tby smtp.gmail.com with ESMTPSA id\n\tj15sm6240715ioo.27.2017.07.27.09.26.30\n\t(version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);\n\tThu, 27 Jul 2017 09:26:30 -0700 (PDT)"],"Authentication-Results":["ozlabs.org;\n\tdkim=fail reason=\"signature verification failed\" (2048-bit key;\n\tunprotected) header.d=kernel-dk.20150623.gappssmtp.com\n\theader.i=@kernel-dk.20150623.gappssmtp.com\n\theader.b=\"BYjzJqgq\"; 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Linux x86_64; rv:52.0) Gecko/20100101\n\tThunderbird/52.2.1","MIME-Version":"1.0","In-Reply-To":"<1501166846.2516.1.camel@wdc.com>","Content-Type":"text/plain; charset=utf-8","Content-Language":"en-US","Content-Transfer-Encoding":"7bit","X-BeenThere":"linuxppc-dev@lists.ozlabs.org","X-Mailman-Version":"2.1.23","Precedence":"list","List-Id":"Linux on PowerPC Developers Mail List\n\t","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Cc":"\"linux-block@vger.kernel.org\" ,\n\t\"linuxppc-dev@lists.ozlabs.org\" ,\n\t\"linux-kernel@vger.kernel.org\" ","Errors-To":"linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org","Sender":"\"Linuxppc-dev\"\n\t"}},{"id":1731650,"web_url":"http://patchwork.ozlabs.org/comment/1731650/","msgid":"<87lgn9dqx3.fsf@concordia.ellerman.id.au>","date":"2017-07-28T06:19:36","subject":"Re: blk_mq_sched_insert_request: inconsistent {SOFTIRQ-ON-W} ->\n\t{IN-SOFTIRQ-W} usage","submitter":{"id":46580,"url":"http://patchwork.ozlabs.org/api/people/46580/","name":"Michael Ellerman","email":"mpe@ellerman.id.au"},"content":"Jens Axboe writes:\n> On 07/27/2017 08:47 AM, Bart Van Assche wrote:\n>> On Thu, 2017-07-27 at 08:02 -0600, Jens Axboe wrote:\n>>> The bug looks like SCSI running the queue inline from IRQ\n>>> context, that's not a good idea.\n...\n>> \n>> scsi_run_queue() works fine if no scheduler is configured. Additionally, that\n>> code predates the introduction of blk-mq I/O schedulers. I think it is\n>> nontrivial for block driver authors to figure out that a queue has to be run\n>> from process context if a scheduler has been configured that does not support\n>> to be run from interrupt context.\n>\n> No it doesn't, you could never run the queue from interrupt context with\n> async == false. So I don't think that's confusing at all, you should\n> always be aware of the context.\n>\n>> How about adding WARN_ON_ONCE(in_interrupt()) to\n>> blk_mq_start_hw_queue() or replacing the above patch by the following:\n>\n> No, I hate having dependencies like that, because they always just catch\n> one of them. Looks like the IPR path that hits this should just offload\n> to a workqueue or similar, you don't have to make any scsi_run_queue()\n> async.\n\nOK, so the resolution is \"fix it in IPR\" ?\n\ncheers","headers":{"Return-Path":"","X-Original-To":["patchwork-incoming@ozlabs.org","linuxppc-dev@lists.ozlabs.org"],"Delivered-To":["patchwork-incoming@ozlabs.org","linuxppc-dev@lists.ozlabs.org"],"Received":["from lists.ozlabs.org (lists.ozlabs.org [103.22.144.68])\n\t(using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby ozlabs.org (Postfix) with ESMTPS id 3xJdy84w2kz9s03\n\tfor ;\n\tFri, 28 Jul 2017 16:20:48 +1000 (AEST)","from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3])\n\tby lists.ozlabs.org (Postfix) with ESMTP id 3xJdy83tSqzDrSJ\n\tfor ;\n\tFri, 28 Jul 2017 16:20:48 +1000 (AEST)","from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2])\n\t(using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby lists.ozlabs.org (Postfix) with ESMTPS id 3xJdwn14LzzDrMS\n\tfor ;\n\tFri, 28 Jul 2017 16:19:37 +1000 (AEST)","from authenticated.ozlabs.org (localhost [127.0.0.1])\n\t(using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128\n\tbits)) (No client certificate requested)\n\tby ozlabs.org (Postfix) with ESMTPSA id 3xJdwm6lXTz9s65;\n\tFri, 28 Jul 2017 16:19:36 +1000 (AEST)"],"From":"Michael Ellerman ","To":"Jens Axboe , Bart Van Assche , \n\tBrian J King ","Subject":"Re: blk_mq_sched_insert_request: inconsistent {SOFTIRQ-ON-W} ->\n\t{IN-SOFTIRQ-W} usage","In-Reply-To":"<5b85a365-faa1-3987-9b6b-270399c30686@kernel.dk>","References":"<87a83qfosu.fsf@concordia.ellerman.id.au>\n\t<073ed79c-11ce-e86c-a905-91fd28675d47@kernel.dk>\n\t<1501166846.2516.1.camel@wdc.com>\n\t<5b85a365-faa1-3987-9b6b-270399c30686@kernel.dk>","User-Agent":"Notmuch/0.21 (https://notmuchmail.org)","Date":"Fri, 28 Jul 2017 16:19:36 +1000","Message-ID":"<87lgn9dqx3.fsf@concordia.ellerman.id.au>","MIME-Version":"1.0","Content-Type":"text/plain","X-BeenThere":"linuxppc-dev@lists.ozlabs.org","X-Mailman-Version":"2.1.23","Precedence":"list","List-Id":"Linux on PowerPC Developers Mail List\n\t","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Cc":"\"linux-block@vger.kernel.org\" ,\n\t\"linuxppc-dev@lists.ozlabs.org\" ,\n\t\"linux-kernel@vger.kernel.org\" ","Errors-To":"linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org","Sender":"\"Linuxppc-dev\"\n\t"}}]