From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1523476968; cv=none; d=google.com; s=arc-20160816; b=y/rM2gdwweO3xUSAw4MuofozbbrMa40a7vB2DTPxDyRWVJcOCUTgYfV3emjBZVr8vJ WqkK/NBmDDw+HanZdGUiL3hDvidFztrO8WLDJ8CExot3ETl0ZygAYiELv3P3kmdh9aJ0 8iIwhQq2laz+XX8NLn9UJ8dPTxRUXEM8fkoqctyar6GWWnPgmALyq1z4xUg5Oh1P3REY 7uMWF05nD1il56DY8eAzl+uqIYGh2S+RADH8MF6GFPMib/M9EqV57vlrA1CnvMNOehaw 6NUaGjC6oK0+XAeQh7tv2pmu5jKWlt2kMmR5h8oZNN4ujfqS8mAPXTTgIqIEHKFQJY4B TIaw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:sender:dkim-signature :arc-authentication-results; bh=3YblijLOLfe55AXEfCl6feQPQFwBPib9WExUPz/7CGg=; b=e+JlimaW6RF1R2hsNOGjac1MsihDUQ3FcFfgMyQUBDS/wlkUjtzkoThuNNRzQ290+n uSJW8Ha8AvHIjcBFTZqkjunCkHnUSNCJMbMUy/S/KzMVGMZl2eTN4cC3JUaSuZspbQmI /nnLWcjMYUXv+URAF5rIEcExQ9zuB/CoT4SPUFOVSziBRGMb1MSrn9EPgZ0GTW0/N4tL 8aV6Jn8HnNDsnCurGaCHvUeDMzGVf7HqkKuhGgRThml7vebCQYqxdv/nivDKmhz60ESI mwOikYKTg2JxGcS1mXHwkRcOOFDp94VhYQ/mJWJJR9afnhlhweRKiRyfTpLFvcY7hVCc 3iVA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=qk2/T0Kx; spf=pass (google.com: domain of htejun@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=htejun@gmail.com Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=qk2/T0Kx; spf=pass (google.com: domain of htejun@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=htejun@gmail.com X-Google-Smtp-Source: AIpwx48nZxXb7RnAVDloja8EYU1Z3RM+7bPDwIFnLd8ra8BL3n+6+ye0lybNV+wWCxQZCyF964/zLQ== Sender: Tejun Heo Date: Wed, 11 Apr 2018 13:02:45 -0700 From: "tj@kernel.org" To: Bart Van Assche Cc: "linux-kernel@vger.kernel.org" , "linux-block@vger.kernel.org" , "nborisov@suse.com" , "axboe@kernel.dk" , "shli@fb.com" , "gregkh@linuxfoundation.org" , "00moses.alexander00@gmail.com" <00moses.alexander00@gmail.com>, "joseph.qi@linux.alibaba.com" , "arnd@arndb.de" Subject: Re: [PATCH v2] blk-cgroup: remove entries in blkg_tree before queue release Message-ID: <20180411200245.GQ793541@devbig577.frc2.facebook.com> References: <20180407102148.GA9729@gmail.com> <20180409220938.GI3126663@devbig577.frc2.facebook.com> <20180411101242.GA2322@gmail.com> <20180411142019.GG793541@devbig577.frc2.facebook.com> <20180411142859.GB2322@gmail.com> <5fafe1cbf6b0111448a81005c1c16feee24a99ad.camel@wdc.com> <20180411190027.GA21274@gmail.com> <20180411195700.GP793541@devbig577.frc2.facebook.com> <6e2d8be78572fef5fe8f2e0e7ecbdea5839dc198.camel@wdc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6e2d8be78572fef5fe8f2e0e7ecbdea5839dc198.camel@wdc.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1597082451728716242?= X-GMAIL-MSGID: =?utf-8?q?1597481385285255280?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Wed, Apr 11, 2018 at 08:00:29PM +0000, Bart Van Assche wrote: > On Wed, 2018-04-11 at 12:57 -0700, tj@kernel.org wrote: > > On Wed, Apr 11, 2018 at 01:55:25PM -0600, Bart Van Assche wrote: > > > On 04/11/18 13:00, Alexandru Moise wrote: > > > > But the root cause of it is in blkcg_init_queue() when blkg_create() returns > > > > an ERR ptr, because it tries to insert into a populated index into blkcg->blkg_tree, > > > > the entry that we fail to remove at __blk_release_queue(). > > > > > > Hello Alex, > > > > > > Had you considered something like the untested patch below? > > > > But queue init shouldn't fail here, right? > > Hello Tejun, > > Your question is not entirely clear to me. Are you referring to the atomic > allocations in blkg_create() or are you perhaps referring to something else? Hmm.. maybe I'm confused but I thought that the fact that blkcg_init_queue() fails itself is already a bug, which happens because a previously destroyed queue left behind blkgs. Thanks. -- tejun