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=-10.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,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 50A9DC48BDF for ; Tue, 15 Jun 2021 09:22:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 228B56115C for ; Tue, 15 Jun 2021 09:22:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231187AbhFOJZA (ORCPT ); Tue, 15 Jun 2021 05:25:00 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:38251 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231174AbhFOJZA (ORCPT ); Tue, 15 Jun 2021 05:25:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1623748975; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=ZomdBvWBdBzyU/KO6r7jol9LTqc+0xLihxqhqLJmkTQ=; b=V92+kNwK1cy1FMsAR+BZZYjGXdMOyMSoFF+OXFCz3wiwebLfU0lq+69aIhgBkuHmHievpF KWiOaFxctr9cC72eHrWFfn8jatcXiCUYmz7prd/lJp8GUcQCR+4g63nf/U19xLE/jh7qW5 QLULFS6LolI/dZ1i9Go4rsFYxzQtEiU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-431-Y-vBG5rQMk6n_mSUZ2ld4w-1; Tue, 15 Jun 2021 05:22:53 -0400 X-MC-Unique: Y-vBG5rQMk6n_mSUZ2ld4w-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id ED2F7803621; Tue, 15 Jun 2021 09:22:52 +0000 (UTC) Received: from T590 (ovpn-12-39.pek2.redhat.com [10.72.12.39]) by smtp.corp.redhat.com (Postfix) with ESMTPS id AE7115D6D1; Tue, 15 Jun 2021 09:22:47 +0000 (UTC) Date: Tue, 15 Jun 2021 17:22:43 +0800 From: Ming Lei To: Omar Kilani Cc: linux-block@vger.kernel.org Subject: Re: Deadlock in wbt / rq-qos Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Sun, Jun 13, 2021 at 08:49:47AM -0700, Omar Kilani wrote: > Hi there, > > I appear to have stumbled upon a deadlock in wbt or rq-qos. > > My journal of a lot of data points is over here: > > https://github.com/openzfs/zfs/issues/12204 > > I initially deadlocked on RHEL 8.4's 4.18.0-305.3.1.el8_4.x86_64 > kernel, but the code in blk-wbt.c / blk-rq-qos.c is functionally > identical to 5.13.0-rc5, so I tried that and I'm able to deadlock that > as well. I believe the same code exists all the way back to 5.0.1. Recently Jan Kara fixed one rq-qos deadlock issue, can you check if the following patch fixes your issue? https://lore.kernel.org/linux-block/e14aeaa7-45a3-b2f0-7738-3613189ae1d4@kernel.dk/T/#t Thanks, Ming