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Thu, 16 Jan 2020 21:04:40 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 00GKx8IO192747; Thu, 16 Jan 2020 21:04:39 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by userp3030.oracle.com with ESMTP id 2xjxm7jbrd-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 16 Jan 2020 21:04:38 +0000 Received: from abhmp0012.oracle.com (abhmp0012.oracle.com [141.146.116.18]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 00GL4b25002166; Thu, 16 Jan 2020 21:04:37 GMT Received: from [10.154.185.48] (/10.154.185.48) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 16 Jan 2020 13:04:37 -0800 Subject: Re: [RFC 2/2] io_uring: acquire ctx->uring_lock before calling io_issue_sqe() To: Jens Axboe Cc: linux-block@vger.kernel.org, Christoph Hellwig , Keith Busch References: <1579142266-64789-1-git-send-email-bijan.mottahedeh@oracle.com> <1579142266-64789-3-git-send-email-bijan.mottahedeh@oracle.com> <9b359dde-3bb6-5886-264b-4bee90be9e25@kernel.dk> <8f7986c7-e5b4-8f24-1c71-666c01b16c8b@kernel.dk> <1397cd55-37a6-4e14-91ac-eb3c35e7d962@kernel.dk> <18346d15-d89d-9d28-1ef8-77574d44dce7@kernel.dk> From: Bijan Mottahedeh Message-ID: <229bd8ea-cd65-c77a-ad58-2a79f3bd0c5b@oracle.com> Date: Thu, 16 Jan 2020 13:04:29 -0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <18346d15-d89d-9d28-1ef8-77574d44dce7@kernel.dk> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Antivirus: Avast (VPS 200115-2, 01/15/2020), Outbound message X-Antivirus-Status: Clean X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9502 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001160170 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9502 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001160170 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 1/16/2020 12:02 PM, Jens Axboe wrote: > On 1/16/20 12:08 PM, Bijan Mottahedeh wrote: >> On 1/16/2020 8:22 AM, Jens Axboe wrote: >>> On 1/15/20 9:42 PM, Jens Axboe wrote: >>>> On 1/15/20 9:34 PM, Jens Axboe wrote: >>>>> On 1/15/20 7:37 PM, Bijan Mottahedeh wrote: >>>>>> io_issue_sqe() calls io_iopoll_req_issued() which manipulates poll_list, >>>>>> so acquire ctx->uring_lock beforehand similar to other instances of >>>>>> calling io_issue_sqe(). >>>>> Is the below not enough? >>>> This should be better, we have two that set ->in_async, and only one >>>> doesn't hold the mutex. >>>> >>>> If this works for you, can you resend patch 2 with that? Also add a: >>>> >>>> Fixes: 8a4955ff1cca ("io_uring: sqthread should grab ctx->uring_lock for submissions") >>>> >>>> to it as well. Thanks! >>> I tested and queued this up: >>> >>> https://git.kernel.dk/cgit/linux-block/commit/?h=io_uring-5.5&id=11ba820bf163e224bf5dd44e545a66a44a5b1d7a >>> >>> Please let me know if this works, it sits on top of the ->result patch you >>> sent in. >>> >> That works, thanks. >> >> I'm however still seeing a use-after-free error in the request >> completion path in nvme_unmap_data().  It happens only when testing with >> large block sizes in fio, typically > 128k, e.g. bs=256k will always hit it. >> >> This is the error: >> >> DMA-API: nvme 0000:00:04.0: device driver tries to free DMA memory it >> has not allocated [device address=0x6b6b6b6b6b6b6b6b] [size=1802201963 >> bytes] >> >> and this warning occasionally: >> >> WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IDLE); >> >> It seems like a request might be issued multiple times but I can't see >> anything in io_uring code that would account for it. > Both of them indicate reuse, and I agree I don't think it's io_uring. It > really feels like an issue with nvme when a poll queue is shared, but I > haven't been able to pin point what it is yet. > > The 128K is interesting, that would seem to indicate that it's related to > splitting of the IO (which would create > 1 IO per submitted IO). > Where does the split take place?  I had suspected that it might be related to the submit_bio() loop in __blkdev_direct_IO() but I don't think I saw multiple submit_bio() calls or maybe I missed something. --bijan