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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1FACDC433F5 for ; Fri, 26 Nov 2021 17:26:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233280AbhKZR3t (ORCPT ); Fri, 26 Nov 2021 12:29:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45980 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232659AbhKZR1s (ORCPT ); Fri, 26 Nov 2021 12:27:48 -0500 Received: from mail-io1-xd34.google.com (mail-io1-xd34.google.com [IPv6:2607:f8b0:4864:20::d34]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B156FC061D60 for ; Fri, 26 Nov 2021 08:55:46 -0800 (PST) Received: by mail-io1-xd34.google.com with SMTP id m9so12258449iop.0 for ; Fri, 26 Nov 2021 08:55:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20210112.gappssmtp.com; s=20210112; h=subject:from:to:cc:references:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=EDS2/0OZnN8Yw+lCiybES2eHP22JnKrPW2o1V5evDOM=; b=C8QmUu5hmXhMVkzBdut4hMaRUJyacbRIH2gubo8jLLug4HOxGfUGyOX7Aj7Z7WCYUU T8JtghGeNN/hdEmGKj/oJLP4r48bg19eBGqUhlazqGqf37TmzWS8cGJcHRQ+vEFKjihW BQVUk5S+/nDT/C18fqfPXmJn5FSzjMluFSZiwOhLBpk5irQtZLYD2wXTqu10XcTUIUd+ l1YuErzdPW75uoyQ35KqiLnOn7zvPVltnJSkPboOWS81OXi+Y/952LDYumkpXF2rJllQ kJYg2tuPihnth2wptLShDnwpKKM00gxvH0MizjMYSVOKlb7BUjtDNA45/9pkuaQqEN4a epnw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:subject:from:to:cc:references:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=EDS2/0OZnN8Yw+lCiybES2eHP22JnKrPW2o1V5evDOM=; b=AAUGt12MpQL9UgOiDmZqhjAuqYgV8UFC6EIQnB848DuqS1OyIOWb0j6ZUSw51mBSk3 xMlp9NCeR/1I+uCLnZ745SoXiENqECGef8ea3FpMOUVUFC7rPXHBKy5bFHHDlVZUNvOu KPtH0FkqthwlfMopqj+DpZJ3e0P9wvJh0+ah4GdUW19tG6tQ+wxLujHVeTSybE5s0lBO jUCoWvHNh5o60yt4w72o5JnJrxvFi5/SAFeosLJvDE8PFOePKPhQAT4k13iE9aHUrIt+ tTpUw91LB8AcKgHxIhhLTZPQwefgNifwwEL4NtdJYq9a+5h+7iPSK8xXeAt21PBKNArl LyHQ== X-Gm-Message-State: AOAM530rRV5mlVuajqEnQKV7bqEAq5+8ur4SlUojML/Du3j337vgNISJ PoGSPjyBv8qJYjaoAOltEjSx0JgNxe+qn48F X-Google-Smtp-Source: ABdhPJyGf22J9LsH+edxTWD8Sx95AqHqfhbWPFlW1x0SNo1dVmZWhAj3Jr0JMoStWOPH8QteD33X5Q== X-Received: by 2002:a05:6602:1581:: with SMTP id e1mr36874278iow.64.1637945745338; Fri, 26 Nov 2021 08:55:45 -0800 (PST) Received: from [192.168.1.116] ([66.219.217.159]) by smtp.gmail.com with ESMTPSA id z6sm4258907ioq.35.2021.11.26.08.55.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 26 Nov 2021 08:55:44 -0800 (PST) Subject: Re: I/O hang with v5.16-rc2 From: Jens Axboe To: Shinichiro Kawasaki , "linux-block@vger.kernel.org" Cc: Johannes Thumshirn , Damien Le Moal References: <20211126095352.bkbrvtgfcmfj3wkj@shindev> <124f86f8-91db-3a02-702d-5c26b22de107@kernel.dk> Message-ID: Date: Fri, 26 Nov 2021 09:55:44 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <124f86f8-91db-3a02-702d-5c26b22de107@kernel.dk> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 11/26/21 9:21 AM, Jens Axboe wrote: > On 11/26/21 2:53 AM, Shinichiro Kawasaki wrote: >> I ran my test set on v5.16-rc2 and observed a process hang. The test work load >> repeats file creation on xfs on dm-zoned. This dm-zoned device is on top of 3 >> dm-linear devices. One of them is dm-linear device on non-zoned NVMe device as >> the cache of the dm-zoned device. The other two are dm-linear devices on zoned >> SMR HDDs. So far, the hang is recreated 100% with my test system. >> >> The kernel message [2] reported hanging tasks. In the call stack, I observe >> wbt_wait(). Also I observed "inflight 1" value in the "rqos/wbt/inflight" >> attribute of debug sysfs. >> >> # grep -R . /sys/kernel/debug/block/nvme0n1 | grep inflight >> /sys/kernel/debug/block/nvme0n1/rqos/wbt/inflight:0: inflight 1 >> /sys/kernel/debug/block/nvme0n1/rqos/wbt/inflight:1: inflight 0 >> /sys/kernel/debug/block/nvme0n1/rqos/wbt/inflight:2: inflight 0 >> >> These symptoms look related to another issue reported to linux-block [1]. As >> discussed in that thread, I set 0 to /sys/block/nvme0n1/queue/wbt_lat_usec. >> With this setting, I observed the hang disappeared. Then this hang I observe >> also related to writeback throttling for the NVMe device. >> >> I bisected and found the commit 4f5022453acd ("nvme: wire up completion batching >> for the IRQ path") is the trigger commit. I reverted this commit from v5.16-rc2, >> and observed the hang disappeared. >> >> Wish this report helps. >> >> >> [1] https://lore.kernel.org/linux-block/b3ba57a7-d363-9c17-c4be-9dbe86875@panix.com > > Yes looks the same as that one, and that commit was indeed my suspicion > on what could potentially cause the accounting discrepancy. I'll take a > look at this. I sent out a patch in the other thread, please give that a whirl. -- Jens Axboe