8.2.3. Finding a Kernel Function That Caused the D Process State

If there are too many processes in the D state and you can’t find out what is happening, issue the following command:

# objdump -Dr /boot/vmlinux-\`uname -r\` >/tmp/kernel.dump

and then get the process list:

# ps axfwln
  F UID   PID  PPID PRI NI  VSZ  RSS  WCHAN STAT TTY TIME COMMAND
100   0 20418 20417  17  0 2588  684      - R    ?   0:00 ps axfwln
100   0     1     0   8  0 1388  524 145186 S    ?   0:00 init
040   0  8670     1   9  0 1448  960 145186 S    ?   0:00 syslogd -m 0
040   0  8713     1  10  0 1616 1140 11ea02 S    ?   0:00 crond

Look for a number under the WCHAN column for the process in question. Then, open /tmp/kernel.dump in an editor, find that number in the first column and then scroll backward to the first function name, which can look like this:

"c011e910 <sys_nanosleep>:"

Then you can tell if the process "lives" or is blocked into the found function.

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