I quite oftenly use below command to know the same..
# ps -eopid,tt,user,fname,tmout,f,wchan
The important bit here is “WCHAN” field and the “COMMAND” field.. “WCHAN” points to the “sleeping function” in kernel mode..
WCHAN : address of the kernel function where the process is sleeping (use wchan if you want the kernel
function name). Running tasks will display a dash (‘-‘) in this column.
[root@humbles-lap ~]$ ps -eopid,tt,user,fname,tmout,f,wchan
PID TT USER COMMAND TMOUT F WCHAN
1 ? root systemd – 4 epoll_wait
2 ? root kthreadd – 1 kthreadd
3 ? root ksoftirq – 1 run_ksoftirqd
6 ? root migratio – 1 cpu_stopper_thread
7 ? root watchdog – 5 watchdog
21 ? root cpuset – 1 rescuer_thread
22 ? root khelper – 1 rescuer_thread
23 ? root kdevtmpf – 5 devtmpfsd
24 ? root netns – 1 rescuer_thread
25 ? root sync_sup – 1 bdi_sync_supers
26 ? root bdi-defa – 1 bdi_forker_thread
27 ? root kintegri – 1 rescuer_thread
28 ? root kblockd – 1 rescuer_thread
29 ? root ata_sff – 1 rescuer_thread
30 ? root khubd – 1 hub_thread
31 ? root md – 1 rescuer_thread
55 ? root kswapd0 – 1 kswapd
56 ? root ksmd – 1 ksm_scan_thread
57 ? root khugepag – 1 khugepaged_alloc_sleep
58 ? root fsnotify – 1 fsnotify_mark_destroy
59 ? root crypto – 1 rescuer_thread
65 ? root kthrotld – 1 rescuer_thread
66 ? root scsi_eh_ – 1 scsi_error_handler
67 ? root scsi_eh_ – 1 scsi_error_handler
68 ? root scsi_eh_ – 1 scsi_error_handler
69 ? root scsi_eh_ – 1 scsi_error_handler
70 ? root scsi_eh_ – 1 scsi_error_handler
71 ? root scsi_eh_ – 1 scsi_error_handler
79 ? root kpsmouse – 1 rescuer_thread
130 ? root ttm_swap – 1 rescuer_thread
311 ? root kdmflush – 1 rescuer_thread
320 ? root jbd2/dm- – 1 kjournald2
321 ? root ext4-dio – 1 rescuer_thread
355 ? root kauditd – 1 kauditd_thread
357 ? root udevd – 4 poll_schedule_timeout
378 ? root systemd- – 4 epoll_wait
391 ? root kvm-irqf – 1 rescuer_thread
640 ? root ips-adju – 1 ips_adjust
641 ? root ips-moni – 1 ips_monitor
648 ? root cfg80211 – 1 rescuer_thread
661 ? root hci0 – 1 rescuer_thread
671 ? root iwlwifi – 1 rescuer_thread
688 ? root hd-audio – 1 rescuer_thread
736 ? root hd-audio – 1 rescuer_thread
772 ? root flush-25 – 1 bdi_writeback_thread
775 ? root kdmflush – 1 rescuer_thread
802 ? root kjournal – 1 kjournald
811 ? root jbd2/sda – 1 kjournald2
812 ? root ext4-dio – 1 rescuer_thread
829 ? root bluetoot – 4 poll_schedule_timeout
841 ? avahi avahi-da – 4 poll_schedule_timeout
859 ? root abrtd – 0 poll_schedule_timeout
862 ? avahi avahi-da – 1 unix_stream_recvmsg
890 ? root gpm – 5 hrtimer_nanosleep
893 ? root NetworkM – 4 poll_schedule_timeout
895 ? root mcelog – 4 poll_schedule_timeout
*********** Truncated
Hope this helps!!