Re: broken "fast" build - hung containers

[Ted Zlatanov]

I was able to replicate the bug by going into one of the hung containers
and running `make check`. It hangs in the module tests, and ends with a
kernel fault (this is 4.4.0). It seems that the
`module--help-function-arglist` test is the last one to succeed, and
`module--test-assertions--load-non-live-object` is the next one that may
be the failing one.

```
# docker exec -it [hung-container-ID] bash
# make -C lib all
make[1]: Entering directory '/checkout/lib'
...
GEN      src/editfns-tests.log
GEN      src/emacs-module-tests.log
2021 Sep 18 06:39:13 emba kernel BUG at 
/build/linux-Pv5wqf/linux-4.4.0/mm/memory.c:3214!
2021 Sep 18 06:39:13 emba RIP  [<ffffffff811cd1ae>] 
handle_mm_fault+0x13de/0x1b80

^C

Makefile:181: recipe for target 'src/emacs-module-tests.log' failed
make[3]: *** [src/emacs-module-tests.log] Interrupt
Makefile:335: recipe for target 'check-doit' failed
make[2]: [check-doit] Interrupt (ignored)
Makefile:305: recipe for target 'check' failed
make[1]: *** [check] Interrupt
Makefile:988: recipe for target 'check' failed
make: *** [check] Interrupt
```

So. I removed emacs-module-tests.* and the test kept going until
process-tests.* where it locked up with the same kernel bug.

I removed process-tests.* as well, and all the tests completed.

Could we disable the emacs-module-tests.el and process-tests.el inside
EMBA Docker?

For the EMBA admins: this can be replicated with

docker exec -it $(docker ps -q|shuf|head -1) bash

and then `make check` (which will randomly pick one of the dozens of
hung containers). I can dig further if someone can give me steps to
follow.

Thanks
Ted