[etherlab-users] INFO: task EtherCAT-EoE:4263 blocked for more than 120 seconds

Gavin Lambert gavin.lambert at tomra.com
Wed May 22 02:51:23 CEST 2019

Try reconfiguring Etherlab with --enable-rtmutex.  This performs better in PREEMPT_RT mode anyway, and certainly will alter that particular code path.

Otherwise, be careful with your threading.  IIRC in RTAI mode you had to supply your own mutex callbacks; in user mode these should usually be removed because it will use standard Linux mutexes instead.  But you still need to be careful to use some APIs only from the RT cyclic thread and some APIs only when that thread is not running.

Unfortunately, I don’t use EoE myself, so I can't provide much further help.

Gavin Lambert
Senior Software Developer


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-----Original Message-----
From: Bilko AS, Oguz Dilmac
Sent: Tuesday, 21 May 2019 21:26
To: etherlab-users at etherlab.org
Subject: [etherlab-users] INFO: task EtherCAT-EoE:4263 blocked for more than 120 seconds


We are moving from RTAI kernel space (2.6.32 32 bit kernel) application to PREEMPT-RT user space application. We are using Gavin's patch set on kernel 4.9.130 64bit kernel.

After around 15 hours of testing with servo drives, we see these kernel messages and our cyclic task hangs:

[62495.878833] INFO: task EtherCAT-EoE:4263 blocked for more than 120 seconds.
[62495.878848]       Tainted: G           OE   4.9.130-rt125 #2 [62495.878855] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" 
disables this message.
[62495.878861] EtherCAT-EoE    D    0  4263      2 0x00000000 [62495.878872]  ffff8a26b5b24200 ffff8a26b5b24200 ffff8a26bfc9cd40
[62495.878885]  ffff8a26b3da5a00 ffffaf52019bfd48 ffffffffba6cb64b
[62495.878923]  ffff8a26bfc9cd40 ffffaf52019bfd50 ffff8a26b3da5a00
[62495.878934] Call Trace:
[62495.878949]  [<ffffffffba6cb64b>] ? __schedule+0x24b/0x580 [62495.878956]  [<ffffffffba6cb9bd>] schedule+0x3d/0xd0 [62495.878962]  [<ffffffffba6ce85b>] schedule_timeout+0x29b/0x420 [62495.878969]  [<ffffffffba6ccf96>] __down+0x76/0xc0 [62495.878977]  [<ffffffffb9eb6d00>] ? cpu_cgroup_can_attach+0x80/0xb0 [62495.878984]  [<ffffffffb9ede2c1>] down+0x41/0x50 [62495.879014]  [<ffffffffc0696d06>] ec_master_eoe_thread+0xb6/0x210 [ec_master] [62495.879039]  [<ffffffffc0696c50>] ? ecrt_master_reset+0x40/0x40 [ec_master] [62495.879045]  [<ffffffffb9eaf1a8>] kthread+0xe8/0x100 [62495.879052]  [<ffffffffb9eaf0c0>] ? kthread_park+0x60/0x60 [62495.879057]  [<ffffffffba6d0477>] ret_from_fork+0x57/0x70

We didn't have such an error with RTAI.

What can I check?

Best regards,


Oguz Dilmac
ARGE Bolumu

Bilko AS, R&D Department
Perpa Ticaret Merkezi B Blok Kat 11 Nr. 1740
TR-34384 Okmeydani Istanbul Turkey
Tel : +90 212 220 07 40  Fax :   +90 212 210 47 01
e-mail : odilmac at bilko-automation.com
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