os/signal: test timeout (entire VM hangs) on netbsd/386 (7.0.1 GENERIC)

[minux]

I upgraded the netbsd/386 builder to the latest 7.0.1 release,
and suddenly a lot of the builds fail at os/signal.

E.g.
timeout:
https://build.golang.org/log/f4c637234824467172beb3c7fdaf61fbd403d55c
illegal instruction:
https://build.golang.org/log/d1841610bb2fd982671f4db6bd8d1836a0a2d735
(this log also shows a failure in runtime/pprof, which might be interesting
as well.)
SIGTRAP:
https://build.golang.org/log/7275a54c64635553b418a15a58475698cf772f64

Repeated run of os/signal tests showed that it's failing in TestStress.

/cc @ianlancetaylor any ideas?

[bradfitz]

Ian is on vacation.

[bradfitz]

/cc @bsiegert @mdempsky

[bsiegert]

Is that the same as #10027?

[minux]

the test timeout part is different from #10027. but they might have the same cause.

[minux]

The problem on netbsd is even worse, the builder VM freezes (sometimes restarts automatically) after a few builds. so far I haven't been able to capture a copy of the kernel messages yet. there isn't any log on the console.

[ianlancetaylor]

See if you can get the strace output (or dtruss, or whatever it is called on NetBSD) of signal.test -test.short -test.run=TestStress.

Sounds like something is going wrong if a signal is received while handling that signal. Or, it's a problem with the alternate signal stack.

[rsc]

If the entire builder VM freezes then it's probably not Go's fault. Sounds like a kernel problem.