Re: [RING_BUFFER_BENCHMARK] INFO: task rb_producer:73 blocked for more than 120 seconds.

From: Fengguang Wu
Date: Tue Nov 21 2017 - 08:29:08 EST


On Tue, Nov 21, 2017 at 08:12:33PM +0800, Fengguang Wu wrote:
Hello,

FYI this happens in mainline kernel 4.14.0-10087-g8c60969.
It happens since 4.11.

Sorry it occurs once in 4.10, too.

/pkg/linux/i386-randconfig-sb0-10121726/gcc-5/c470abd4fde40ea6a0846a2beab642a578c0b8cd/dmesg-vm-lkp-wsx03-openwrt-i386-23:20171016024929:i386-randconfig-sb0-10121726:4.10.0:1

[ 363.022350] CE: Reprogramming failure. Giving up
[ 373.638060] INFO: task rb_producer:43 blocked for more than 120 seconds.
[ 373.638158] Not tainted 4.10.0 #1
[ 373.638189] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 373.638216] rb_producer D 7500 43 2 0x00000000
[ 373.639902] Call Trace:
[ 373.640643] __schedule+0xde8/0x118f
[ 373.651470] ? rewind_stack_do_exit+0x12/0x12
[ 373.651510] schedule+0x4e/0xc0
[ 373.651566] schedule_timeout+0x2a/0x6d9
[ 373.651597] ? wait_for_common+0x4e/0x2cb
[ 373.651631] ? _raw_spin_unlock_irq+0x60/0x16f
[ 373.651666] ? trace_hardirqs_on_caller+0x36b/0x3b1
[ 373.651698] ? preempt_count_sub+0xdd/0xf7
[ 373.652222] ? native_irq_disable+0x22/0x22
[ 373.683202] wait_for_common+0x250/0x2cb
[ 373.706893] ? do_task_dead+0xad/0xad
[ 373.732749] wait_for_completion+0x25/0x35
[ 373.732785] ring_buffer_producer+0x26a/0x818
[ 373.758544] ? do_task_dead+0xad/0xad
[ 373.767747] ring_buffer_producer_thread+0xa0/0x1b2
[ 373.767806] kthread+0x1b1/0x1c4
[ 373.767846] ? wait_to_die+0xaa/0xaa
[ 373.767880] ? __kthread_create_on_node+0x2c7/0x2c7
[ 373.796586] ret_from_fork+0x21/0x30
[ 373.796617]
[ 373.796617] Showing all locks held in the system:
[ 373.798861] 2 locks held by khungtaskd/17:
[ 373.800187] #0: (rcu_read_lock){......}, at: [<81172016>] watchdog+0x124/0x6d1
[ 373.800287] #1: (tasklist_lock){.+.+..}, at: [<810e574a>] debug_show_all_locks+0x72/0x2d3
[ 373.800702] 2 locks held by askfirst/123:
[ 373.802453] #0: (&tty->ldisc_sem){.+.+.+}, at: [<819b98ac>] ldsem_down_read+0x46/0x58
[ 373.802546] #1: (&ldata->atomic_read_lock){+.+...}, at: [<81565de8>] n_tty_read+0x115/0xbe4
[ 373.804460]
[ 373.804465] =============================================
[ 373.804465]
[ 373.831299] Kernel panic - not syncing: hung_task: blocked tasks
[ 373.831358] CPU: 0 PID: 17 Comm: khungtaskd Not tainted 4.10.0 #1
[ 373.831363] Call Trace:
[ 373.831720] dump_stack+0x40/0x5e
[ 373.831809] panic+0x1b5/0x4a3
[ 373.831849] check_hung_task+0x3d4/0x51d
[ 373.831882] watchdog+0x269/0x6d1
[ 373.831936] kthread+0x1b1/0x1c4
[ 373.831979] ? check_hung_task+0x51d/0x51d
[ 373.832038] ? __kthread_create_on_node+0x2c7/0x2c7
[ 373.832230] ret_from_fork+0x21/0x30
[ 373.832400] Kernel Offset: disabled
[ 376.677470] Rebooting in 3 seconds..

Fengguang