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[157.230.128.187]) by smtp.gmail.com with ESMTPSA id x71sm9855165pfd.129.2020.04.13.20.38.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Apr 2020 20:38:05 -0700 (PDT) Received: by 42.do-not-panic.com (Postfix, from userid 1000) id EF98140277; Tue, 14 Apr 2020 03:38:04 +0000 (UTC) Date: Tue, 14 Apr 2020 03:38:04 +0000 From: Luis Chamberlain To: Bart Van Assche Cc: Jens Axboe , Al Viro , Greg Kroah-Hartman , Steven Rostedt , Ingo Molnar , Jan Kara , Ming Lei , Nicolai Stange , Andrew Morton , Michal Hocko , yu kuai , linux-block@vger.kernel.org, Linux FS Devel , linux-mm , "linux-kernel@vger.kernel.org" , Omar Sandoval , Hannes Reinecke , Michal Hocko Subject: Re: [RFC v2 5/5] block: revert back to synchronous request_queue removal Message-ID: <20200414033804.GO11244@42.do-not-panic.com> References: <20200409214530.2413-1-mcgrof@kernel.org> <20200409214530.2413-6-mcgrof@kernel.org> <161e938d-929b-1fdb-ba77-56b839c14b5b@acm.org> <20200410143412.GK11244@42.do-not-panic.com> <64c9212d-aaa3-d172-0ab9-0fc0e25a019a@acm.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <64c9212d-aaa3-d172-0ab9-0fc0e25a019a@acm.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Apr 11, 2020 at 04:21:17PM -0700, Bart Van Assche wrote: > On 2020-04-10 14:27, Luis Chamberlain wrote: > > On Fri, Apr 10, 2020 at 2:50 PM Luis Chamberlain wrote: > >> > >> On Fri, Apr 10, 2020 at 8:34 AM Luis Chamberlain wrote: > >>> On Thu, Apr 09, 2020 at 08:12:21PM -0700, Bart Van Assche wrote: > >>>> Please add a might_sleep() call in blk_put_queue() since with this patch > >>>> applied it is no longer allowed to call blk_put_queue() from atomic context. > >>> > >>> Sure thing. > >> > >> On second though, I don't think blk_put_queue() would be the right > >> place for might_sleep(), given we really only care about the *last* > >> refcount decrement to 0. So I'll move it to blk_release_queue(). > >> Granted, at that point we are too late, and we'd get a splat about > >> this issue *iff* we really sleep. So yeah, I do suppose that forcing > >> this check there still makes sense. > > > > I'll add might_sleep() to both blk_release_queue() *and* blk_cleanup_queue(). > > Since there is already an unconditional mutex_lock() call in > blk_cleanup_queue(), do we really need to add a might_sleep() call in > blk_cleanup_queue()? You are right, mutex_lock() already has a might_sleep() sprinkled on it. Luis