linux-kernel - [lkp-robot] [sched/clock] acb04058de: INFO:suspicious_RCU

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Message-ID: <20170208013633.GD2568@yexl-desktop>
Date:   Wed, 8 Feb 2017 09:36:33 +0800
From:   kernel test robot <xiaolong.ye@...el.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Ingo Molnar <mingo@...nel.org>, Mike Galbraith <efault@....de>,
        Borislav Petkov <bp@...en8.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>, lkp@...org
Subject: [lkp-robot] [sched/clock]  acb04058de: INFO:suspicious_RCU_usage


FYI, we noticed the following commit:

commit: acb04058de49458010c44bb35b849d45113fd668 ("sched/clock: Fix hotplug crash")
https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master

in testcase: cpu-hotplug
with following parameters:




on test machine: qemu-system-x86_64 -enable-kvm -cpu Nehalem -smp 2 -m 1G

caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):


+-------------------------------------+------------+------------+
|                                     | 02cfdc95a0 | acb04058de |
+-------------------------------------+------------+------------+
| boot_successes                      | 4          | 0          |
| boot_failures                       | 0          | 4          |
| INFO:suspicious_RCU_usage           | 0          | 4          |
| RCU_used_illegally_from_offline_CPU | 0          | 4          |
+-------------------------------------+------------+------------+




[   30.328035] masked ExtINT on CPU#1
[   30.328035] 
[   30.328035] ===============================
[   30.328035] [ INFO: suspicious RCU usage. ]
[   30.328035] 4.10.0-rc3-00271-gacb0405 #1 Not tainted
[   30.328035] -------------------------------
[   30.328035] kernel/workqueue.c:712 sched RCU or wq_pool_mutex should be held!
[   30.328035] 
[   30.328035] other info that might help us debug this:
[   30.328035] 
[   30.328035] 
[   30.328035] RCU used illegally from offline CPU!
[   30.328035] rcu_scheduler_active = 1, debug_locks = 0
[   30.328035] no locks held by swapper/1/0.
[   30.328035] 
[   30.328035] stack backtrace:
[   30.328035] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.10.0-rc3-00271-gacb0405 #1
[   30.328035] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.3-20161025_171302-gandalf 04/01/2014
[   30.328035] Call Trace:
[   30.328035]  dump_stack+0x86/0xc0
[   30.328035]  lockdep_rcu_suspicious+0xf7/0x100
[   30.328035]  get_work_pool+0x55/0xa6


To reproduce:

        git clone git://git.kernel.org/pub/scm/linux/kernel/git/wfg/lkp-tests.git
        cd lkp-tests
        bin/lkp qemu -k <bzImage> job-script  # job-script is attached in this email



Thanks,
Xiaolong

View attachment "config-4.10.0-rc3-00271-gacb0405" of type "text/plain" (79366 bytes)

View attachment "job-script" of type "text/plain" (3836 bytes)

Download attachment "dmesg.xz" of type "application/octet-stream" (21928 bytes)