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Wed, 1 Jul 2020 14:16:32 +0000 (GMT) Subject: Re: [PATCH] blk-mq: put driver tag when this request is completed To: Ming Lei Cc: Jens Axboe , linux-block@vger.kernel.org, Christoph Hellwig , Bartlomiej Zolnierkiewicz From: Marek Szyprowski Message-ID: <2fcd389f-b341-7cd1-692b-8c9d1918198a@samsung.com> Date: Wed, 1 Jul 2020 16:16:32 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <20200701134512.GA2443512@T590> Content-Transfer-Encoding: 7bit Content-Language: en-US X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrAKsWRmVeSWpSXmKPExsWy7djPc7oHZ/2JM5h4S9Vi9d1+NouNM9az WqxcfZTJYu8tbYtDk5uZHFg9Lp8t9dh9s4HN4/2+q2wefVtWMXp83iQXwBrFZZOSmpNZllqk b5fAlXH10zmWgl08Fd9X3WFuYGzj6mLk5JAQMJE4s+85YxcjF4eQwApGiSPzXzFBOF8YJbq6 O9ggnM+MEh82b2XvYuQAa/l1pxAivpxR4s/VH1BF7xkldqy6wQIyV1jAS2LRoR9gtoiAksTd u6vZQYqYBaYySnT2bWQCSbAJGEp0ve1iA7F5Bewkfs64xQxiswioSKw7eQIsLioQK9G3dAFU jaDEyZlPwIZyCuhItN6ZB1bPLCAvsf3tHChbXOLWk/lgP0gILGKX+Pt0JyPEpy4Sh9d+YoKw hSVeHd/CDmHLSPzfCdPQzCjx8Nxadginh1HictMMqG5riTvnfrGBAoBZQFNi/S59iLCjRNPX Y4yQcOGTuPFWEOIIPolJ26YzQ4R5JTrahCCq1SRmHV8Ht/bghUvMExiVZiF5bRaSd2YheWcW wt4FjCyrGMVTS4tz01OLDfNSy/WKE3OLS/PS9ZLzczcxAtPN6X/HP+1g/Hop6RCjAAejEg9v RsWfOCHWxLLiytxDjBIczEoivE5nT8cJ8aYkVlalFuXHF5XmpBYfYpTmYFES5zVe9DJWSCA9 sSQ1OzW1ILUIJsvEwSnVwKg6+95lh7TIlp9WZr/vhahvY8qI5E77LrJuye/VAfKGzbOzDzuY Z2w9cXx+0Y2c57fuFc5Rcv3wrzBtF+8EW80/v9SUQxOYgkoybf2z45e3JqUYx2elXDsjuzwz cE+I3E6b54WCnkvDNEP9lnrM1hauSJssvOGizYoP03b/2/TBxsR2q3/KNiWW4oxEQy3mouJE AK1piLEzAwAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrEIsWRmVeSWpSXmKPExsVy+t/xu7oHZ/2JM+hexm6x+m4/m8XGGetZ LVauPspksfeWtsWhyc1MDqwel8+Weuy+2cDm8X7fVTaPvi2rGD0+b5ILYI3SsynKLy1JVcjI Ly6xVYo2tDDSM7S00DMysdQzNDaPtTIyVdK3s0lJzcksSy3St0vQy7j66RxLwS6eiu+r7jA3 MLZxdTFycEgImEj8ulPYxcjFISSwlFHi7vrv7F2MnEBxGYmT0xpYIWxhiT/Xutggit4ySpx/ fBUsISzgJbHo0A8WEFtEQEni7t3V7CBFzALTGSV2nPjHCtHxlFFiyaSfbCBVbAKGEl1vu8Bs XgE7iZ8zbjGD2CwCKhLrTp4Ai4sKxEp8u7cFqkZQ4uTMJ2AbOAV0JFrvzAOrZxYwk5i3+SGU LS+x/e0cKFtc4taT+UwTGIVmIWmfhaRlFpKWWUhaFjCyrGIUSS0tzk3PLTbUK07MLS7NS9dL zs/dxAiMr23Hfm7ewXhpY/AhRgEORiUe3oyKP3FCrIllxZW5hxglOJiVRHidzp6OE+JNSays Si3Kjy8qzUktPsRoCvTcRGYp0eR8YOznlcQbmhqaW1gamhubG5tZKInzdggcjBESSE8sSc1O TS1ILYLpY+LglGpgDF/jHbFuf4TufN4Tpbsm3PDK4zo7LWHyp64Dv1tatD+sNLrPY3D4YJCt 0yPm87znDy6UrdC8y244afPb2dcWN588/Ub/bLLgz5rk2r9739Vx7Q5aPf1HkHLG4b+/1+VW OIqpN79Z6xPNfN/y8gER5kksuQevBXHu6qj5/c1PN+egYWRnS+OmE0osxRmJhlrMRcWJAKvL SDbFAgAA X-CMS-MailID: 20200701141633eucas1p2ee702b156fa1ddfba113615a851434f6 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20200701130104eucas1p1f8dcce58bf704b726aee1e89980fe19e X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20200701130104eucas1p1f8dcce58bf704b726aee1e89980fe19e References: <20200629094759.2002708-1-ming.lei@redhat.com> <57fb09b1-54ba-f3aa-f82c-d709b0e6b281@samsung.com> <20200701134512.GA2443512@T590> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Hi Ming, On 01.07.2020 15:45, Ming Lei wrote: > On Wed, Jul 01, 2020 at 03:01:03PM +0200, Marek Szyprowski wrote: >> On 29.06.2020 11:47, Ming Lei wrote: >>> It is natural to release driver tag when this request is completed by >>> LLD or device since its purpose is for LLD use. >>> >>> One big benefit is that the released tag can be re-used quicker since >>> bio_endio() may take too long. >>> >>> Meantime we don't need to release driver tag for flush request. >>> >>> Cc: Christoph Hellwig >>> Signed-off-by: Ming Lei >> This patch landed recently in linux-next as commit 36a3df5a4574. Sadly >> it causes a regression on one of my test systems (ARM 32bit, Samsung >> Exynos5422 SoC based Odroid XU3 board with eMMC). The system boots fine >> and then after a few seconds every executed command hangs. No >> panic/ops/any other message. I will try to provide more information asap >> I find something to share. Simple reverting it in linux-next is not >> possible due to dependencies. > What is the exact eMMC's driver code(include the host driver)? dwmmc-exynos (drivers/mmc/host/dw_mmc-exynos.c) > The usual way for handling completion is that host driver notifies block > layer via blk_mq_complete_request() after the LLD specific handling for > this request is done. > > However, there might be driver which may use rq->tag in its rq completion > handler. I will see if the special case can be dealt with once you share > the driver info. Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland