ps command output does not display wchan values in fedora

Solution 1:

This is a Fedora bug which affects at least Fedora 31 and 32 (#1879450).

Note that the ps man page you are quoting from is outdated - current ps versions directly read the symbolic wchan information from /proc/$pid/wchan.

Looking at the stack walking procedure it seems that it simply doesn't work without frame pointers. CONFIG_SCHED_OMIT_FRAME_POINTER isn't the only relevant parameter here, also relevant (on Fedora) seems to be:

ONFIG_UNWINDER_ORC=y
# CONFIG_UNWINDER_FRAME_POINTER is not set

See also this 2013 Debian bug report about wchan breakage.

/proc/$pid/stack can be used as a substitute for missing wchan information.

See also my answer to a similar question.