From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ming Lei Subject: Re: [PATCH] blk-mq: Fix several SCSI request queue lockups Date: Tue, 5 Dec 2017 09:04:29 +0800 Message-ID: <20171205010428.GB8365@ming.t460p> References: <20171204173032.16330-1-bart.vanassche@wdc.com> <20171204224200.GA6888@ming.t460p> <1512427697.2795.14.camel@wdc.com> <20171204230151.GD6888@ming.t460p> <1512430346.2795.34.camel@wdc.com> <20171205002040.GA8365@ming.t460p> <1512433798.2795.45.camel@wdc.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1512433798.2795.45.camel@wdc.com> Sender: linux-block-owner@vger.kernel.org To: Bart Van Assche Cc: "jthumshirn@suse.de" , "linux-block@vger.kernel.org" , "hch@lst.de" , "martin.petersen@oracle.com" , "axboe@kernel.dk" , "linux-scsi@vger.kernel.org" , "hare@suse.com" , "jejb@linux.vnet.ibm.com" List-Id: linux-scsi@vger.kernel.org On Tue, Dec 05, 2017 at 12:29:59AM +0000, Bart Van Assche wrote: > On Tue, 2017-12-05 at 08:20 +0800, Ming Lei wrote: > > Also it is a bit odd to see request in hctx->dispatch now, and it can only > > happen now when scsi_target_queue_ready() returns false, so I guess you apply > > some change on target->can_queue(such as setting it as 1 in srp/ib code > > manually)? > > Yes, but that had already been mentioned. From the e-mail at the start of > this e-mail thread: "Change the SRP initiator such that SCSI target queue > depth is limited to 1." The changes I made in the SRP initiator are the same > as those described in the following message from about one month ago: > https://www.spinics.net/lists/linux-scsi/msg114720.html. OK, got it. Then no reason to revert commit(0df21c86bdbf scsi: implement .get_budget an .put_budget for blk-mq) for one issue which may never happen in reality since this reproducer need out-of-tree patch. I don't mean it isn't a issue, but I don't think it has top priority for reverting commit 0df21c86bdbf. Especially there isn't proof shown that 0df21c86bdbf causes this issue since this commit won't change run queue for requests in hctx->dispatch_list. I's like to take a look if someone'd like to cooperate, such as providing kernel log, test debug patch, and kind of things. Or when I get this hardware to reproduce. -- Ming