ps -aux | grep "I<" root 4 0.0 0.0 0 0 ? I< 16:15 0:00 [kworker/0:0H] root 6 0.0 0.0 0 0 ? I< 16:15 0:00 [mm_percpu_wq] root 18 0.0 0.0 0 0 ? I< 16:15 0:00 [kworker/1:0H] root 24 0.0 0.0 0 0 ? I< 16:15 0:00 [kworker/2:0H] root 30 0.0 0.0 0 0 ? I< 16:15 0:00 [kworker/3:0H] root 32 0.0 0.0 0 0 ? I< 16:15 0:00 [netns] root 40 0.0 0.0 0 0 ? I< 16:15 0:00 [writeback] root 44 0.0 0.0 0 0 ? I< 16:15 0:00 [crypto] root 45 0.0 0.0 0 0 ? I< 16:15 0:00 [kintegrityd] root 46 0.0 0.0 0 0 ? I< 16:15 0:00 [kblockd] root 47 0.0 0.0 0 0 ? I< 16:15 0:00 [ata_sff] root 48 0.0 0.0 0 0 ? I< 16:15 0:00 [md] root 49 0.0 0.0 0 0 ? I< 16:15 0:00 [edac-poller] root 50 0.0 0.0 0 0 ? I< 16:15 0:00 [devfreq_wq] root 51 0.0 0.0 0 0 ? I< 16:15 0:00 [watchdogd] root 56 0.0 0.0 0 0 ? I< 16:15 0:00 [kworker/u9:0] root 99 0.0 0.0 0 0 ? I< 16:15 0:00 [kthrotld] root 100 0.0 0.0 0 0 ? I< 16:15 0:00 [acpi_thermal_pm] root 102 0.0 0.0 0 0 ? I< 16:15 0:00 [ipv6_addrconf] root 111 0.0 0.0 0 0 ? I< 16:15 0:00 [kstrp] root 129 0.0 0.0 0 0 ? I< 16:15 0:00 [charger_manager] root 177 0.0 0.0 0 0 ? I< 16:15 0:00 [scsi_tmf_0] root 179 0.0 0.0 0 0 ? I< 16:15 0:00 [scsi_tmf_1] root 181 0.0 0.0 0 0 ? I< 16:15 0:00 [scsi_tmf_2] root 183 0.0 0.0 0 0 ? I< 16:15 0:00 [scsi_tmf_3] root 185 0.0 0.0 0 0 ? I< 16:15 0:00 [scsi_tmf_4] root 187 0.0 0.0 0 0 ? I< 16:15 0:00 [scsi_tmf_5] root 193 0.0 0.0 0 0 ? I< 16:15 0:00 [e1000e] root 202 0.0 0.0 0 0 ? I< 16:15 0:00 [kworker/3:1H] root 205 0.0 0.0 0 0 ? I< 16:15 0:00 [kworker/0:1H] root 229 0.0 0.0 0 0 ? I< 16:15 0:00 [ext4-rsv-conver] root 273 0.0 0.0 0 0 ? I< 16:15 0:00 [kworker/2:1H] root 285 0.0 0.0 0 0 ? I< 16:15 0:00 [kworker/1:1H] 1 Answer
It does appear in the man page:
PROCESS STATE CODES Here are the different values that the s, stat and state output specifiers (header "STAT" or "S") will display to describe the state of a process: D uninterruptible sleep (usually IO) I Idle kernel thread R running or runnable (on run queue) S interruptible sleep (waiting for an event to complete) T stopped by job control signal t stopped by debugger during the tracing W paging (not valid since the 2.6.xx kernel) X dead (should never be seen) Z defunct ("zombie") process, terminated but not reaped by its parent For BSD formats and when the stat keyword is used, additional characters may be displayed: < high-priority (not nice to other users) N low-priority (nice to other users) L has pages locked into memory (for real-time and custom IO) s is a session leader l is multi-threaded (using CLONE_THREAD, like NPTL pthreads do) + is in the foreground process group 
