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

[Fengguang Wu]

On Tue, Jul 26, 2016 at 09:52:40AM -0500, Eric W. Biederman wrote:
> Fengguang Wu <fengguang.wu@xxxxxxxxx> writes:
> > On Mon, Jul 25, 2016 at 01:57:00PM -0500, Eric W. Biederman wrote:
> > > kernel test robot <xiaolong.ye@xxxxxxxxx> writes:
> [snip]
> > > > [   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.
>
> Is it possible to include a url pointing to a page of documentation
> holding this information in your emails or alternatively a url pointing
> to some source code.  Just so other people don't have to ask you this
> question.

Yes that's the right directions to follow. We'll make the reports more
understandable and the test/bisects more reliable.

In particular, I suspect this false report might be related to QEMU
watchdog. The wild guess is, if trinity touches the watchdog device by
accident, it may result in the VM reset w/o any symptom.

> > > 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
>
> Thank you for verifying this.

You are welcome!

Thanks,
Fengguang