From: Jens Axboe Subject: Re: INFO: task hung in blk_queue_enter Date: Sat, 2 Jun 2018 07:48:26 -0600 Message-ID: <0B5A5D8D-BA17-45C2-BCF7-609CDCF1A8DB@kernel.dk> References: <6db16aa3a7c56b6dcca2d10b4e100a780c740081.camel@wdc.com> <201805220652.BFH82351.SMQFFOJOtFOVLH@I-love.SAKURA.ne.jp> <201805222020.FEJ82897.OFtJMFHOVLQOSF@I-love.SAKURA.ne.jp> <25708e84-6f35-04c3-a2e4-6854f0ed9e78@I-love.SAKURA.ne.jp> <20180601234946.GA655@ming.t460p> <95c419d8-7f19-f9c0-a53f-3d381fe93176@kernel.dk> <20180602023622.GA2306@ming.t460p> <20180602045353.GA20257@ming.t460p> Mime-Version: 1.0 (1.0) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Cc: Tetsuo Handa , Bart.VanAssche@wdc.com, dvyukov@google.com, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, jthumshirn@suse.de, alan.christopher.jenkins@gmail.com, syzbot+c4f9cebf9d651f6e54de@syzkaller.appspotmail.com, martin.petersen@oracle.com, dan.j.williams@intel.com, hch@lst.de, oleksandr@natalenko.name, martin@lichtvoll.de, hare@suse.com, syzkaller-bugs@googlegroups.com, ross.zwisler@linux.intel.com, keith.busch@intel.com, linux-ext4@vger.kernel.org To: Ming Lei Return-path: In-Reply-To: <20180602045353.GA20257@ming.t460p> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org > On Jun 1, 2018, at 10:54 PM, Ming Lei wrote: >=20 >> On Fri, Jun 01, 2018 at 10:31:13PM -0600, Jens Axboe wrote: >> On 6/1/18 8:36 PM, Ming Lei wrote: >>>> clear the bit when we need to, potentially even adding a debug check to= >>>> blk_queue_enter_live() that complains if the ref was not already >>>> elevated. Though that would be expensive, compared to the percpu inc >>>> now. Not saying the bit is necessarily the best way forward, but I do >>>> like it a LOT more than adding an argument to generic_make_request. >>>=20 >>> We may introduce generic_make_request_with_ref() for blk_queue_split(), >>> what do you think of the following patch? >>=20 >> Functionally it'll work as well. >=20 > If you are fine with this one, I'm glad to prepare for a normal one, > so that we can save one precious bio flag, and the total number is > just 13. We=E2=80=99ve never had much issue with bio specific flags, I prefer that ap= proach to a wrapper around generic_make_request().=20