From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753703AbdEIPOM (ORCPT ); Tue, 9 May 2017 11:14:12 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:60657 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751436AbdEIPOK (ORCPT ); Tue, 9 May 2017 11:14:10 -0400 Authentication-Results: vger.kernel.org; dkim=none (message not signed) header.d=none;vger.kernel.org; dmarc=none action=none header.from=fb.com; Subject: Re: get/put_cpu() usage in block/blk-mq.c To: Mike Galbraith References: <1494310029.20252.44.camel@gmx.de> <1494342256.4440.3.camel@gmx.de> CC: LKML From: Jens Axboe Message-ID: <842b9fc5-5a8e-d147-0b14-3c9f9540336d@fb.com> Date: Tue, 9 May 2017 09:13:59 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <1494342256.4440.3.camel@gmx.de> Content-Type: text/plain; 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linux-kernel@vger.kernel.org On 05/09/2017 09:04 AM, Mike Galbraith wrote: > On Tue, 2017-05-09 at 08:53 -0600, Jens Axboe wrote: >> On 05/09/2017 12:07 AM, Mike Galbraith wrote: >>> Hi Jens, >>> >>> I was about to fix up this splat.. >>> >>> [ 445.022141] loop: module loaded >>> [ 445.078116] BUG: using smp_processor_id() in preemptible [00000000] code: loop0/3801 >>> [ 445.085873] caller is debug_smp_processor_id+0x17/0x20 >>> [ 445.091016] CPU: 7 PID: 3801 Comm: loop0 Tainted: G E 4.12.0-default #40 >>> [ 445.098838] Hardware name: IBM System x3550 M3 -[7944K3G]-/69Y5698 , BIOS -[D6E150AUS-1.10]- 12/15/2010 >>> [ 445.108564] Call Trace: >>> [ 445.111016] dump_stack+0x65/0x89 >>> [ 445.114330] check_preemption_disabled+0xde/0xf0 >>> [ 445.118945] debug_smp_processor_id+0x17/0x20 >>> [ 445.123300] blk_stat_add+0xb0/0x130 >>> [ 445.126876] __blk_mq_complete_request+0xb5/0x150 >>> [ 445.131575] blk_mq_complete_request+0x16/0x20 >>> [ 445.136020] loop_queue_work+0x5f/0xaa0 [loop] >>> [ 445.140461] ? _raw_spin_unlock_irq+0x21/0x40 >>> [ 445.144816] ? finish_task_switch+0x85/0x270 >>> [ 445.149085] ? __schedule+0x291/0x8c0 >>> [ 445.152747] kthread_worker_fn+0xc2/0x1d0 >>> [ 445.156754] kthread+0x114/0x150 >>> [ 445.159983] ? __kthread_init_worker+0xb0/0xb0 >>> [ 445.164424] ? kthread_park+0x60/0x60 >>> [ 445.168085] ret_from_fork+0x2c/0x40 >> >> Is it from this_cpu_ptr() in blk_stat_add()? > > Yeah. So why is this complaining, doesn't rcu_read_lock() disable preemption? -- Jens Axboe