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

[Fengguang Wu]

Hi Eric,

Sorry for the delay!

On Mon, Jul 25, 2016 at 01:57:00PM -0500, Eric W. Biederman wrote:
> kernel test robot <xiaolong.ye@xxxxxxxxx> writes:
>
> > FYI, we noticed the following commit:
> >
> > https://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git 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

Regards,
Fengguang