Bug 239352 - kernel panic - cause as yet undetermined
Summary: kernel panic - cause as yet undetermined
Status: New
Alias: None
Product: Base System
Classification: Unclassified
Component: kern (show other bugs)
Version: 12.0-RELEASE
Hardware: amd64 Any
: --- Affects Some People
Assignee: freebsd-bugs mailing list
Keywords: panic
Depends on:
Reported: 2019-07-20 20:47 UTC by Ronald F. Guilmette
Modified: 2019-08-19 21:24 UTC (History)
2 users (show)

See Also:

/v/crash/core.txt.0 (331.23 KB, text/plain)
2019-08-03 19:33 UTC, Ronald F. Guilmette
no flags Details
/v/crash/core.txt.1 file dated 2019-08-04 (384.01 KB, text/plain)
2019-08-19 21:24 UTC, Ronald F. Guilmette
no flags Details

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Description Ronald F. Guilmette 2019-07-20 20:47:40 UTC
I got a kernel panic on 12.0-RELEASE a couple of days ago.  Fortunately, I was already set up to get the crash file(s).

That's the good news.

The bad news is that now I have no idea what I'm supposed to do with this stuff.  Somebody please instruct me.  I want to be of help to get this bug out of the kernel, if I can.
Comment 1 Mark Johnston freebsd_committer 2019-07-20 20:59:37 UTC
If your system successfully saved a crash dump, you'll see files called /var/crash/core.txt.*.  Attaching them here would be a useful start.
Comment 2 Ronald F. Guilmette 2019-07-20 21:20:13 UTC
Just to be 100% clear, my personal /var partition doesn't have much space on it, so I had previously set the folliowing in my /etc/rc.conf file:


and that dir is where all of the relevant files from my recent kernel panic are.

There is only one file matching the filename pattern you gave and it is called /v/crash/core.txt.0

It's current content are as follows:

'version' has unknown type; cast it to its declared type
'version' has unknown type; cast it to its declared type
Unable to find matching kernel for /v/crash/vmcore.0

That's it.  Just those three lines.

I don't have any idea what this stuff is actually *supposed* to look like, but offhand I would guess that this ain't it.

What went wrong?  My kernel is 100% stock 12.0-RELEASE.  It has not been fiddled by me at all.  uname -a gives the following:

FreeBSD segfault.tristatelogic.com 12.0-RELEASE FreeBSD 12.0-RELEASE r341666 GENERIC  amd64

OK, so now what?
Comment 3 Mark Johnston freebsd_committer 2019-07-21 15:09:03 UTC
Do you have kernel debug symbols available under /usr/lib/debug/boot/kernel/?  Do you install the kernel to a non-default location?
Comment 4 Ronald F. Guilmette 2019-07-21 19:25:09 UTC
(In reply to Mark Johnston from comment #3)

The directory /usr/lib/debug/boot/kernel/ exists on my system, but it is devoid of any content.

I did not install the kernel in any non-default location.
Comment 5 Mark Johnston freebsd_committer 2019-07-30 13:41:26 UTC
If you are running stock 12.0-RELEASE, i.e., no patches, you can fetch debug symbols from here: ftp.freebsd.org/pub/FreeBSD/releases/amd64/amd64/12.0-RELEASE/kernel-dbg.txz

Then crashinfo(8) should be able to produce a usable summary of the panic.
Comment 6 Ronald F. Guilmette 2019-08-03 19:33:39 UTC
Created attachment 206249 [details]
Comment 7 Ronald F. Guilmette 2019-08-03 19:36:14 UTC
(In reply to Mark Johnston from comment #5)

As requested, I have fetched and unxz'd and untarred the symbols file and then run crashinfo and have now attached the resulting core.txt.0 file.

Please let me know if there's anything else I should do to help with getting to the bottom of this kernel panic.
Comment 8 Mark Johnston freebsd_committer 2019-08-19 16:33:17 UTC
Sorry for the delay in replying.

We panicked because the disk returned an error in response to a write to the UFS journal:

g_vfs_done():ada3p4[WRITE(offset=-512, length=512)]error = 5
panic: cannot reassign paging buffer

That offset however seems strange and suggests a software issue.  Is the panic reproducible, or have you only seen it the one time?
Comment 9 Ronald F. Guilmette 2019-08-19 21:17:37 UTC
Actually, I have had 1 more kernel panic also on August 4.  And once again I got a dump file.  I'm sorry that I have not had time to deal with this since then, but I still do have that dump file.  I will try now to do the steps that I was instructed to do for the last one, and will try to get the new info uploaded so that you can take a look.  Maybe it is the same problem.  Maybe a different one.  I am sure that I do not know.  I hope you will tell me.
Comment 10 Ronald F. Guilmette 2019-08-19 21:24:36 UTC
Created attachment 206712 [details]
/v/crash/core.txt.1 file dated 2019-08-04

Apparently, having a proper set of symbols files already installed on my system means that I don't (and didn't) have to manually run crashdump myself.  This file just appeared automagically following the last kernel panic on August 4.