From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:58076 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750892AbdIBCxJ (ORCPT ); Fri, 1 Sep 2017 22:53:09 -0400 Date: Sat, 2 Sep 2017 10:52:54 +0800 From: Ming Lei To: Bart Van Assche Cc: "linux-block@vger.kernel.org" , "hch@infradead.org" , "martin.petersen@oracle.com" , "linux-scsi@vger.kernel.org" , "axboe@fb.com" , "jejb@linux.vnet.ibm.com" , "tj@kernel.org" , "jthumshirn@suse.de" , "oleksandr@natalenko.name" Subject: Re: [PATCH V2 6/8] block: allow to allocate req with REQF_PREEMPT when queue is frozen Message-ID: <20170902025253.GA20047@ming.t460p> References: <20170901184958.19452-1-ming.lei@redhat.com> <20170901184958.19452-8-ming.lei@redhat.com> <1504296423.14386.62.camel@wdc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1504296423.14386.62.camel@wdc.com> Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org On Fri, Sep 01, 2017 at 08:07:04PM +0000, Bart Van Assche wrote: > On Sat, 2017-09-02 at 02:49 +0800, Ming Lei wrote: > > + if ((flags & BLK_MQ_REQ_PREEMPT) && blk_queue_is_freezing(q)) > > + blk_queue_enter_live(q); > > + else > > + ret = blk_queue_enter(q, !(gfp_mask & __GFP_DIRECT_RECLAIM)); > > Why did you repost this patch series without trying to reach an agreement > about the approach? > > Anyway, because of the unsafe blk_queue_enter_live() call introduced by this > patch, please add the following to the description of this patch whenever you > repost it: > > NAK-ed-by: Bart Van Assche Did you take a look at the patch 7 or cover letter? In that patch, if preempt freezing is on-progressing, any other freeze can't be started at all, so that is definitely safe to use blk_queue_enter_live() here, isn't it? -- Ming