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=-2.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 9B9FDC33CAF for ; Thu, 16 Jan 2020 21:26:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6866520748 for ; Thu, 16 Jan 2020 21:26:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="RwlNymGR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731100AbgAPV0z (ORCPT ); Thu, 16 Jan 2020 16:26:55 -0500 Received: from mail-io1-f67.google.com ([209.85.166.67]:42781 "EHLO mail-io1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729476AbgAPV0y (ORCPT ); Thu, 16 Jan 2020 16:26:54 -0500 Received: by mail-io1-f67.google.com with SMTP id n11so23596593iom.9 for ; Thu, 16 Jan 2020 13:26:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=s+M8VHe0TuzsjIREAGxRwrcHLOdmAMPOblK/0F6fo3U=; b=RwlNymGR/BAbNcOf1T1Agvrv+hlgilqGpfOeibGDdaVmE4hzGktVPrIlP2zRxjBPdn 9Y0MqGkEZu61KblDPpM1xMoqLmMPUjVmlb6hH/z+8WHnfGZPosWDE9Jc9DwCrfwGdWV1 K/MdppDBYKMmEMYXJW+gHhp4rrdiCFY0Su0go1gDZ/cuijqZx1QGaG5VbnArFBfpljIq MO0vswsh+s7u7GnoivwxO8tJl+KMj0lWiwJEi/64dKwopi6Ogn/ZqNY8dAdXAgpSKghe fw+8Ls2zwgVF5a1ufnG5Z/gP1zU8XVvM1Kc8cyAV9YkCxsalmpHAxkJIwz+9OSgYiTzu eOzA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=s+M8VHe0TuzsjIREAGxRwrcHLOdmAMPOblK/0F6fo3U=; b=IkNBxpRIwTvyDHVFoAt8zGqYgk1uMujLtWqdf8ECN/gLkAVC5wEhAciJg5wf/mJ3r8 IVUrsMBIwqvNQDT6vjB6rXrV/C4iergHld9QXrP68ZvZcxbQDub+2TENPEkv5PuL0txK bNXbyuzXvXK7zW6BN6X9zXAg8BUz8HZVNgmMOp7YDb1CQHwpNqqlmHykMr04N/dQrHhk 6Y1yUXaioTjEC6V4fHwEHvdOcc1K/T1oEH19cZD0dHgGxod72bpqjNZsFTjcpoG+xQtM GmpjQtvzMjJJZpV2YnV/iNmsMdYgy9k4vm4UoKWqbBG3p3vVZ3/oH/ok8lSP2yH8ROjj oAJA== X-Gm-Message-State: APjAAAV3brV6EQKqZaEuer1UzX0luq7fiXWcx7t6/Zc7f9dHI8igsV2d /qzLafAcDN8h9M+ByMd/hPaMRA== X-Google-Smtp-Source: APXvYqwtYJjjljHa7Oa0UVOe0ZgC7SnEF/Czc0uYJi0RXx2BfElFbGqDtAHAVuNEC6cRfJLfxhvLfg== X-Received: by 2002:a02:c787:: with SMTP id n7mr30712698jao.85.1579210013770; Thu, 16 Jan 2020 13:26:53 -0800 (PST) Received: from [192.168.1.159] ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id h3sm7257251ilh.6.2020.01.16.13.26.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 16 Jan 2020 13:26:53 -0800 (PST) Subject: Re: [RFC 2/2] io_uring: acquire ctx->uring_lock before calling io_issue_sqe() To: Bijan Mottahedeh 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> <229bd8ea-cd65-c77a-ad58-2a79f3bd0c5b@oracle.com> From: Jens Axboe Message-ID: Date: Thu, 16 Jan 2020 14:26:52 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <229bd8ea-cd65-c77a-ad58-2a79f3bd0c5b@oracle.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 1/16/20 2:04 PM, Bijan Mottahedeh wrote: > 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. See the path from blk_mq_make_request() -> __blk_queue_split() -> blk_bio_segment_split(). The bio is built and submitted, then split if it violates any size constraints. The splits are submitted through generic_make_request(), so that might be why you didn't see multiple submit_bio() calls. -- Jens Axboe