kern/55895: panic: kernel diagnostic assertion "(flags & (PR_NOWAIT|PR_LIMITFAIL)) != 0" failed

[gson%gson.org@localhost (Andreas Gustafsson)]

>Number:         55895
>Category:       kern
>Synopsis:       panic: kernel diagnostic assertion "(flags & (PR_NOWAIT|PR_LIMITFAIL)) != 0" failed
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Dec 27 12:05:00 +0000 2020
>Originator:     Andreas Gustafsson
>Release:        NetBSD-current
>Organization:
>Environment:
System: NetBSD
Architecture: sparc
Machine: sparc
>Description:

The TNF sparc testbed has recorded six random panics with the panic
message in the subject line in the last few months.

Here is a link to the log and the panic message for each one:

  http://releng.netbsd.org/b5reports/sparc/commits-2020.08.html#2020.08.10.11.09.15
  detect_unused_tests: [ 50699.6707740] panic: kernel diagnostic assertion "(flags & (PR_NOWAIT|PR_LIMITFAIL)) != 0" failed: file "/tmp/bracket/build/2020.08.10.11.09.15-sparc/src/sys/kern/subr_pool.c", line 1181 

  http://releng.netbsd.org/b5reports/sparc/commits-2020.09.html#2020.09.13.13.03.15
  ldp_regen: [ 26053.9547610] panic: kernel diagnostic assertion "(flags & (PR_NOWAIT|PR_LIMITFAIL)) != 0" failed: file "/tmp/bracket/build/2020.09.13.13.03.15-sparc/src/sys/kern/subr_pool.c", line 1181

  http://releng.netbsd.org/b5reports/sparc/commits-2020.10.html#2020.10.01.02.00.04
  [  18.0342095] panic: kernel diagnostic assertion "(flags & (PR_NOWAIT|PR_LIMITFAIL)) != 0" failed: file "/tmp/build/2020.10.01.02.00.04-sparc/src/sys/kern/subr_pool.c", line 1181 

  http://releng.netbsd.org/b5reports/sparc/commits-2020.11.html#2020.11.05.00.41.04
  crossping: [ 27861.1173080] panic: kernel diagnostic assertion "(flags & (PR_NOWAIT|PR_LIMITFAIL)) != 0" failed: file "/tmp/build/2020.11.05.00.41.04-sparc/src/sys/kern/subr_pool.c", line 1181 

  http://releng.netbsd.org/b5reports/sparc/commits-2020.12.html#2020.09.12.12.11.19
  grow_16M_v1_4096: [ 13917.1767735] panic: kernel diagnostic assertion "(flags & (PR_NOWAIT|PR_LIMITFAIL)) != 0" failed: file "/tmp/build/2020.09.12.12.11.19-sparc/src/sys/kern/subr_pool.c", line 1181 

  http://releng.netbsd.org/b5reports/sparc/commits-2020.12.html#2020.12.26.22.28.35
  ipsec_tunnel_ipv4_ah_hmacripemd160: [ 10851.7832570] panic: kernel diagnostic assertion "(flags & (PR_NOWAIT|PR_LIMITFAIL)) != 0" failed: file "/tmp/build/2020.12.26.22.28.35-sparc/src/sys/kern/subr_pool.c", line 1181 

I'm filing this as category "kern" rather than "port-sparc" because I
suspect it's an MI issue that just happens to hit the sparc testbed
because it has less (emulated) RAM than most.  A crash with the same
panic message has also been reported on evbearm6:

  https://mail-index.netbsd.org/current-users/2018/11/04/msg034522.html

and analyzed:

  https://mail-index.netbsd.org/current-users/2018/11/04/msg034523.html

>How-To-Repeat:

>Fix: