From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 22 Aug 2018 16:06:02 +0800 From: Ming Lei To: Jarkko Nikula Cc: Adrian Hunter , linux-block@vger.kernel.org, linux-mmc@vger.kernel.org, Jens Axboe Subject: Re: SDHCI Regression with 6ce3dd6eec11 ("blk-mq: issue directly if hw queue isn't busy in case of 'none'") Message-ID: <20180822080556.GA31467@ming.t460p> References: <855d68f2-17ed-eaae-2f13-d0ff95b6834f@linux.intel.com> <2f4d5335-15dd-1dea-5d80-36b79455577a@intel.com> <20180821135725.GA28835@ming.t460p> <741127be-7d37-695c-15a9-47186959e639@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <741127be-7d37-695c-15a9-47186959e639@linux.intel.com> List-ID: On Wed, Aug 22, 2018 at 09:06:40AM +0300, Jarkko Nikula wrote: > On 08/21/2018 04:57 PM, Ming Lei wrote: > > On Tue, Aug 21, 2018 at 04:45:41PM +0300, Jarkko Nikula wrote: > > > On 08/21/2018 04:03 PM, Adrian Hunter wrote: > > > > On 21/08/18 15:37, Jarkko Nikula wrote: > > > > > Hi > > > > > > > > > > I bisected some kind of SDHCI regression to commit 6ce3dd6eec11 ("blk-mq: > > > > > issue directly if hw queue isn't busy in case of 'none'") causing dumps > > > > > below and one or more systemd-udevd processes being in uninterruptible sleep > > > > > state preventing safe reboot/shutdown. > > > > > > > > > > This is from an Intel Baytrail based tablet with integrated eMMC but my > > > > > up-to-date Debian/testing rootfs (with systemd) is on USB stick. > > > > > > > > > > It doesn't revert cleanly on today's head 778a33959a8a but issue is gone if > > > > > I go to a commit before 6ce3dd6eec11 and occurs at 6ce3dd6eec11. > > > > > > > > This was discussed here: > > > > > > > > https://marc.info/?l=linux-block&m=153334717506073&w=2 > > > > > > > > Coincidentally, I just sent the fix patch: > > > > > > > > https://marc.info/?l=linux-mmc&m=153485326025301&w=2 > > > > > > > Cool, it fixed my regression. I tested both on top of 6ce3dd6eec11 and head > > > 778a33959a8a. Maybe you would like to add into your patch another fixes tag > > > and my tested by: > > > > > > Fixes: 6ce3dd6eec11 ("blk-mq: issue directly if hw queue isn't busy in case > > > of 'none'") > > > > If you read the above links carefully, you'd see it is wrong to add the tag of > > 'Fixes: 6ce3dd6eec11'. > > > Hmm... why? That commit 6ce3dd6eec11 was clearly regressing on my setup > while Adrian's fix for 81196976ed94 that has been present since v4.16 fixes > my finding too. > > I don't know well enough MMC and block layer but if commit 6ce3dd6eec11 > revealed an issue from MMC under my configuration I'd call it still a > regression. 6ce3dd6eec11 just makes the original issue to happen easier, and the root cause is that MMC's stack doesn't support concurrent dispatch for SDHCI. Thanks, Ming