Re: [LKP] More information please. Re: [fs] 54cc07a761: BUG: kernel test crashed

From: Fengguang Wu
Date: Tue Jul 26 2016 - 10:36:09 EST

Hi Eric,

Sorry for the delay!

On Mon, Jul 25, 2016 at 01:57:00PM -0500, Eric W. Biederman wrote:
kernel test robot <> writes:

FYI, we noticed the following commit: for-testing
commit 54cc07a761deb38318aca64ddf07fc45157c85e0 ("fs: Call d_automount with the filesystems creds")

in testcase: boot

on test machine: 1 threads qemu-system-x86_64 -enable-kvm -cpu Westmere with 320M memory

caused below changes:

| | 8175435777 | 54cc07a761 |
| boot_successes | 102 | 16 |
| boot_failures | 0 | 3 |
| BUG:kernel_test_crashed | 0 | 3 |
| timestamp.last | 0 | 54.951425 |

[ 19.206454] VFS: Warning: trinity-c0 using old stat() call. Recompile your binary.

Elapsed time: 70
BUG: kernel test crashed

What application generated the line "BUG: kernel test crashed."
What flavor of crash was this?

It's a simple boot test with a quick trinity run. So there will be
some randomness in this test.

The "BUG: kernel test crashed" means the VM reboots by itself while
the trinity test is running. If the error message is "BUG: kernel boot
crashed" it'd mean VM abnormally reboots before any test is launched.

Given the last boot test failure that was reported to me was about 10
commits after the problem commit I unfortunately can't take it at face
value that the appropriate commit has been pinpointed.

If you could give me enough information to dig into this that would
be great. Otherwise I am going to have to proceed forward on the basis
that this is a testing robot failure, and that the people who maintain
the testing robot don't care enough to look after it.

I queued more tests in various KVM instances and find the kernel test
crashes can also happen in the parent commit. So it looks like a false
report. Sorry for the noise!

81754357770ebd90 aeaa4a79ff6a5ed912b7362f20
---------------- --------------------------
fail:runs %reproduction fail:runs
| | |
5:100 0% 5:100 dmesg.BUG:kernel_test_crashed
:100 1% 1:100 dmesg.Mem-Info
:100 1% 1:100 dmesg.invoked_oom-killer:gfp_mask=0x