From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH] SCSI: don't get target/host busy_count in scsi_mq_get_budget() To: Ming Lei , Bart Van Assche Cc: "linux-scsi@vger.kernel.org" , "hch@infradead.org" , "linux-block@vger.kernel.org" , "osandov@fb.com" , "john.garry@huawei.com" , "loberman@redhat.com" References: <20171104015534.32684-1-ming.lei@redhat.com> <1509997522.2409.58.camel@wdc.com> <20171107021125.GB15090@ming.t460p> <1510071607.2656.17.camel@wdc.com> <20171108003934.GB20599@ming.t460p> From: Jens Axboe Message-ID: <26ee805b-883f-d588-5649-13700244b6e8@kernel.dk> Date: Tue, 7 Nov 2017 19:55:32 -0700 MIME-Version: 1.0 In-Reply-To: <20171108003934.GB20599@ming.t460p> Content-Type: text/plain; charset=utf-8 List-ID: On 11/07/2017 05:39 PM, Ming Lei wrote: > On Tue, Nov 07, 2017 at 04:20:08PM +0000, Bart Van Assche wrote: >> On Tue, 2017-11-07 at 10:11 +0800, Ming Lei wrote: >>> If you can reproduce, please provide me at least the following log >>> first: >>> >>> find /sys/kernel/debug/block -name tags | xargs cat | grep busy >>> >>> If any pending requests arn't completed, please provide the related >>> info in dbgfs about where is the request. >> >> Every time I ran the above or a similar command its output was empty. I >> assume that's because the hang usually occurs in a phase where these debugfs >> attributes either have not yet been created or have already disappeared. > > Could you dump all tags? Then you can see if this attribute is disappeared. > > If that output is empty, it often means there isn't pending request not > completed. So if that is true, your hang is _not_ related with RESTART. You need to check sched_tags as well. It could still be a restart race or problem, if tags is empty but sched_tags has busy bits. -- Jens Axboe