ubuntu_zram_smoke_test will generate a huge output file and choking jenkins

[Po-Hsu Lin]

[~/test-results/4.4.0-132.158~14.04.1-generic]
$ du -sh * |grep G
1.5G ms10-34-mcdivittB0-kernel__4.4.0-132.158~14.04.1__2018-08-14_10-01-00
6.2G ms10-35-mcdivittB0-kernel__4.4.0-132.158~14.04.1__2018-08-03_23-53-00

[~/test-results/4.4.0-132.158~14.04.1-generic/ms10-35-mcdivittB0-kernel__4.4.0-132.158~14.04.1__2018-08-03_23-53-00]
$ du -sh * |grep G
6.2G ubuntu_zram_smoke_test

[~/test-results/4.4.0-132.158~14.04.1-generic/ms10-35-mcdivittB0-kernel__4.4.0-132.158~14.04.1__2018-08-03_23-53-00/ubuntu_zram_smoke_test/results/ubuntu_zram_smoke_test.zram-smoke-test/mnt]
$ du -sh *
512 lost+found
6.2G test

[Colin Ian King (colin-king)]

FYI, ~/test-results/4.4.0-132.158~14.04.1-generic/ms10-35-mcdivittB0-kernel__4.4.0-132.158~14.04.1__2018-08-03_23-53-00/ubuntu_zram_smoke_test/results/ubuntu_zram_smoke_test.zram-smoke-test/mnt is mounted on /dev/zram0 and is on a memory based zram file system.

The test will populate the file system on /dev/zram0. Is the test crashing or timing out?

[Colin Ian King (colin-king)]

Ah, I see the issue, it's not being umounted for some weird reason. I can debug and fix this now I can see why it's an issue.

[Colin Ian King (colin-king)]

sudo umount /dev/zram0
umount: /home/ubuntu/autotest/client/results/default/ubuntu_zram_smoke_test.zram-smoke-test/mnt: target is busy.

..so the umount is failing, hence leaving the file system populated with a large file that consumes memory. Sigh.

[Colin Ian King (colin-king)]

We have a kernel thread blocked,

root 2880 2 0 08:31 ? 00:00:00 [jbd2/zram0-8] .. and I can't umount the file system.

[Colin Ian King (colin-king)]

09:00:26 ERROR| [stderr] + sync
09:07:58 INFO | Timer expired (1200 sec.), nuking pid 3106

OK - so it looks like the test was being killed and it's not cleaned up properly.

[Colin Ian King (colin-king)]

Fix sent, should be committed by EOD

[Colin Ian King (colin-king)]

@Sam, is this now working OK? If so, can we close this bug?

[Po-Hsu Lin (cypressyew)]

Hi Colin,
the patch was not accepted yet.

[Colin Ian King (colin-king)]

Patch now pushed: http://kernel.ubuntu.com/git/ubuntu/autotest-client-tests.git/commit/?h=master-next&id=a89fa07bae6ceb34f400a241a45740830e69aa69

[Colin Ian King (colin-king)]

Based on Sam's reply:

<PHLin> cking, the zram test looks good

..I'm marking this as fixed.