Unreclaimed swap space upon process termination?

[Thomas Schwinge]

Hi!

Updating a Debian GNU/Hurd virtual machine to recent packages after many
months, and then running the GCC testsuite, I observe the following
behavior, which should be reproducible with the executable in the
attached tarball:

    $ vmstat | grep swap\ free
    swap free:         4096M
    $ ./1.exe 
    $ vmstat | grep swap\ free
    swap free:         3288M
    $ ./1.exe 
    $ vmstat | grep swap\ free
    swap free:         2495M
    $ ./1.exe 
    $ vmstat | grep swap\ free
    swap free:         1726M
    $ ./1.exe 
    $ vmstat | grep swap\ free
    swap free:          931M
    $ ./1.exe 
    $ vmstat | grep swap\ free
    swap free:          164M
    $ ./1.exe 
    Bus error
    $ vmstat | grep swap\ free
    swap free:            0 

At this point, the system doesn't recover from this low memory situation.

For each invocation of the executable, there are three "no more room in
[...]  (./1.exe([...])" messages on the Mach console.

The executable is compiled from
[gcc]/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/insert/char/1.cc
from commit a050099a416f013bda35832b878d9a57b0cbb231 (gcc-6-branch branch
point; 2016-04-15), which doesn't look very spectacular -- apart from
maybe the __gnu_test::set_memory_limits call, which I'll try to figure
out what it does.  But nevertheless, unreclaimed swap space upon process
termination sounds like a bug?

Unless this a known issue, or somebody can quickly pinpoint the problem,
I'll try to bisect core system packages, between the version of the
"good" and "bad" disk images.


Grüße
 Thomas

1.tar.xz
Description: application/xz