panic: object has cached pages on recent HEAD

[Don Lewis]

I just got this panic on my port builder machine running a recent
version of HEAD (last updated in the last few days):

panic: object has cached pages on recent HEAD

As you can see, I was pushing it really hard:

last pid: 76867;  load averages: 62.92, 41.93, 41.40    up 7+10:24:04  13:45:01
448 processes: 97 running, 344 sleeping, 7 stopped
CPU: 79.1% user,  0.0% nice, 20.9% system,  0.0% interrupt,  0.0% idle
Mem: 5887M Active, 163M Inact, 6085M Wired, 17M Cache, 832K Buf, 3658M Free
ARC: 1482M Total, 163M MFU, 663M MRU, 7080K Anon, 70M Header, 579M Other
Swap: 40G Total, 9167M Used, 31G Free, 22% Inuse, 1152K In

  PID USERNAME    THR PRI NICE   SIZE    RES STATE   C   TIME    WCPU COMMAND
73630 root          1  77    0   195M   181M CPU5    5   0:06  37.28% cc1plus
75387 root          1  78    0   209M   193M RUN     2   0:06  36.60% cc1plus
75615 root          1  74    0   150M   133M RUN     7   0:04  36.20% cc1plus
74151 root          1  78    0   306M   290M RUN     0   0:12  31.77% cc1plus
72986 root          1  78    0   282M   264M RUN     5   0:19  30.24% cc1plus
72985 root          1  77    0   292M   272M RUN     1   0:18  28.00% cc1plus
75912 root          1  75    0   106M 97604K RUN     3   0:03  27.73% cc1plus
74501 root          1  80    0   293M   280M RUN     7   0:11  27.14% cc1plus
73442 root          1  77    0   329M   299M RUN     2   0:13  26.54% cc1plus
75715 root          1  75    0 96996K 81424K RUN     3   0:02  22.51% cc1plus
74645 root          1  78    0   252M   236M RUN     6   0:09  21.73% cc1plus
75630 root          1  77    0   208M   189M RUN     4   0:08  19.27% cc1plus
74324 root          1  78    0   322M   308M RUN     4   0:11  19.17% cc1plus
75494 root          1  74    0   138M   126M RUN     4   0:04  19.07% cc1plus
74848 root          1  73    0 98180K 85192K RUN     2   0:02  16.12% cc1plus
76292 root          1  73    0 63108K 46904K RUN     0   0:01  15.92% cc1plus

A screenshot with a backtrace is here:
<https://people.freebsd.org/~truckman/panic_object_has_cached_pages.jpg>

Is there anything I should check in DDB before I reboot?  I can get the
svn revision after I do that.

I've never crashed this machine before, so I don't know if crashdumps
work.