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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 13784C07E85 for ; Fri, 7 Dec 2018 15:15:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D2D6520892 for ; Fri, 7 Dec 2018 15:15:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D2D6520892 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-block-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726065AbeLGPPN (ORCPT ); Fri, 7 Dec 2018 10:15:13 -0500 Received: from mx1.redhat.com ([209.132.183.28]:34236 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726034AbeLGPPN (ORCPT ); Fri, 7 Dec 2018 10:15:13 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BDFBC87621; Fri, 7 Dec 2018 15:15:12 +0000 (UTC) Received: from localhost (unknown [10.18.25.149]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E94F479D62; Fri, 7 Dec 2018 15:15:08 +0000 (UTC) Date: Fri, 7 Dec 2018 10:15:08 -0500 From: Mike Snitzer To: Jens Axboe Cc: "linux-block@vger.kernel.org" , Bart Van Assche , Ming Lei Subject: Re: [PATCH v3] blk-mq: punt failed direct issue to dispatch list Message-ID: <20181207151507.GA20544@redhat.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Fri, 07 Dec 2018 15:15:12 +0000 (UTC) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Fri, Dec 07 2018 at 12:17am -0500, Jens Axboe wrote: > After the direct dispatch corruption fix, we permanently disallow direct > dispatch of non read/write requests. This works fine off the normal IO > path, as they will be retried like any other failed direct dispatch > request. But for the blk_insert_cloned_request() that only DM uses to > bypass the bottom level scheduler, we always first attempt direct > dispatch. For some types of requests, that's now a permanent failure, > and no amount of retrying will make that succeed. This results in a > livelock. > > Instead of making special cases for what we can direct issue, and now > having to deal with DM solving the livelock while still retaining a BUSY > condition feedback loop, always just add a request that has been through > ->queue_rq() to the hardware queue dispatch list. These are safe to use > as no merging can take place there. Additionally, if requests do have > prepped data from drivers, we aren't dependent on them not sharing space > in the request structure to safely add them to the IO scheduler lists. > > This basically reverts ffe81d45322c and is based on a patch from Ming, > but with the list insert case covered as well. > > Fixes: ffe81d45322c ("blk-mq: fix corruption with direct issue") > Cc: stable@vger.kernel.org > Suggested-by: Ming Lei > Reported-by: Bart Van Assche > Signed-off-by: Jens Axboe Looks good, thanks! Acked-by: Mike Snitzer