The sysinfo(2) manual page has some busted markup. First, warnings from the usual checks:
Man page format/spelling:

mandoc: usr/src/man/man2/sysinfo.2:11:2: WARNING: skipping paragraph macro: PP after SH

mandoc: usr/src/man/man2/sysinfo.2:19:2: WARNING: skipping paragraph macro: PP after SH

mandoc: usr/src/man/man2/sysinfo.2:302:2: WARNING: skipping paragraph macro: PP after SH

mandoc: usr/src/man/man2/sysinfo.2:313:2: WARNING: skipping paragraph macro: PP after SH

mandoc: usr/src/man/man2/sysinfo.2:345:2: WARNING: skipping paragraph macro: PP after SH

mandoc: usr/src/man/man2/sysinfo.2:356:2: WARNING: skipping paragraph macro: PP after SH
And, as Andy noted in a recent review, a bunch of headings have duplicate \fB and \fR pairs.

Viewd revised verion manually with man