From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932509AbdJJTAO (ORCPT ); Tue, 10 Oct 2017 15:00:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33262 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932087AbdJJTAM (ORCPT ); Tue, 10 Oct 2017 15:00:12 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 871A147A Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=jcline@redhat.com To: Tony Luck , Borislav Petkov Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, linux-edac@vger.kernel.org, linux-kernel@vger.kernel.org, Laura Abbott From: Jeremy Cline Subject: x86/mce: suspicious RCU usage in 4.13.4 Message-ID: <9840bf0d-6756-75eb-1a2d-d3aace235244@redhat.com> Date: Tue, 10 Oct 2017 15:00:09 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Tue, 10 Oct 2017 19:00:12 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, A Fedora user has reported an issue about suspicious RCU usage in dev-mcelog. It looks like perhaps the notifier call chain is not acquiring the mce_chrdev_read_mutex? The traceback is [36915.633804] ============================= [36915.633805] WARNING: suspicious RCU usage [36915.633808] 4.13.4-301.fc27.x86_64+debug #1 Not tainted [36915.633809] ----------------------------- [36915.633811] arch/x86/kernel/cpu/mcheck/dev-mcelog.c:60 suspicious mce_log_get_idx_check() usage! [36915.633812] other info that might help us debug this: [36915.633813] rcu_scheduler_active = 2, debug_locks = 1 [36915.633815] 3 locks held by kworker/1:2/14637: [36915.633816] #0: ("events"){.+.+.+}, at: [] process_one_work+0x1d0/0x6a0 [36915.633827] #1: ((&mce_work)){+.+...}, at: [] process_one_work+0x1d0/0x6a0 [36915.633833] #2: ((x86_mce_decoder_chain).rwsem){++++..}, at: [] blocking_notifier_call_chain+0x2f/0x70 [36915.633840] stack backtrace: [36915.633843] CPU: 1 PID: 14637 Comm: kworker/1:2 Not tainted 4.13.4-301.fc27.x86_64+debug #1 [36915.633844] Hardware name: Gigabyte Technology Co., Ltd. Z87M-D3H/Z87M-D3H, BIOS F11 08/12/2014 [36915.633847] Workqueue: events mce_gen_pool_process [36915.633849] Call Trace: [36915.633854] dump_stack+0x8e/0xd6 [36915.633858] lockdep_rcu_suspicious+0xc5/0x100 [36915.633862] dev_mce_log+0xf6/0x1e0 [36915.633865] notifier_call_chain+0x39/0x90 [36915.633869] blocking_notifier_call_chain+0x49/0x70 [36915.633873] mce_gen_pool_process+0x41/0x70 [36915.633876] process_one_work+0x253/0x6a0 [36915.633883] worker_thread+0x4d/0x3b0 [36915.633888] kthread+0x133/0x150 [36915.633890] ? process_one_work+0x6a0/0x6a0 [36915.633892] ? kthread_create_on_node+0x70/0x70 [36915.633896] ret_from_fork+0x2a/0x40 For reference, the Red Hat bugzilla is https://bugzilla.redhat.com/show_bug.cgi?id=1498969 Thanks, Jeremy Cline