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Date:      Mon, 10 Aug 2015 14:43:07 -1000
From:      parv <parv@bitter-almonds.com>
To:        Kevin Oberman <rkoberman@gmail.com>,Chris H <bsd-lists@bsdforge.com>
Cc:        FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org>
Subject:   Re: 8-stable crashing recently in ufsdirhash
Message-ID:  <2C865403-726E-42D0-85FB-27880F3EAC45@bitter-almonds.com>
In-Reply-To: <CAN6yY1toptpwfx3-SzpgZLh5%2BWhvmHkRhWQaT33gNn18cRpF0A@mail.gmail.com>
References:  <ED2C19BC-7F91-420E-B8B9-063AB53D3649@bitter-almonds.com> <1438783814.70393.138.camel@freebsd.org> <119E4C6D-ABFD-4D82-B353-D3829088233B@bitter-almonds.com> <8d35eae569c2ef115207bb8a1ac97b53@ultimatedns.net> <CAN6yY1toptpwfx3-SzpgZLh5%2BWhvmHkRhWQaT33gNn18cRpF0A@mail.gmail.com>

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On August 5, 2015 12:20:15 PM HST, Kevin O wrote:
>On Wed, Aug 5, 2015 at 1:15 PM, Chris H wrote:
>
>> On Wed, 05 Aug 2015 09:30:28 -1000 parv 
>wrote
>>
>> > On August 5, 2015 4:10:14 AM HST, Ian L
>> > wrote:
>> > >On Tue, 2015-08-04 at 23:54 -1000, parv wrote:
>> > >> Please CC me as I cannot properly use my laptop, Thinkpad X200
>> > >> (i386).
>> > >>
>> > >> 8-stable has been crashing a lot since source update of Jul
>2015[0].
>> > >> After building debug kernel, kgdb shows lock reversal order & in
>> > >> ufsdirhash. File systems (/, var, misc) are all UFS, with var & misc
>> > >> having soft updates enabled.
...
>> > >> Most recent crash ...
>> > >>
>> > >> http://imagebin.ca/v/2B50NARvIHsH
...
>> > >When you say you built a debug kernel, does that include option
>> > >WITNESS_KDB?  If so, remove that so you can find the real error. LORs
>> > >related to ufs_dirhash have been reported for years, and nobody with
>> > >the
>> > >appropriate skills seems to be interested in fixing them; they just get
>> > >declared to be harmless.
...
>> > I will try that as soon as I can. Currently after every little fs
>> > operation,
>> > I am thrown in debugger-reboot-fsck cycle. As such I cannot do anything.
...
>> > I tried booting
>> > /boot/kernel.old/kernel from boot prompt but that presented debugger soon
>> > after boot.
>> >
>> > BTW is it possible to set kernel.old to boot next time at boot prompt?
...
>> It might be somewhat easier to boot from the boot-only/install
>> CD/DVD, and then choose rescue mode.
>> After you've gotten there. Simply mount "/" in read/write, them open
>> it's /boot/loader.conf, and add the following:
>> kernel="kernel.old"
>> boot_single="YES"
>>
>> and save it. You can then remove the CD/DVD, and reboot which will
>land
>> you in single-user mode, from your kernel.old/kernel.
>> Assuming it booted to that kernel OK, you can run fsck -f
...

Chris, after spending my mail I was thinking on the same lines. But I delayed due to laziness, till ...

>You're working too hard.
>
>You can drop into the loader prompt and enter "boot kernel.old". This
>will
>reload both the kernel and modules from /boot/kernel.old.

Thanks Kevin. It was the loader prompt, not the boot prompt, that I should have tried. After booting old kernel from loader prompt, functionality was restored (to some workable state).

> Also handy and
>virtually unknown is that you can build test kernels and not blow away
>the
>old, working kernel by using "make reinstallkernel" instead of
>installkernel. This will keep the existing kernel.old and just replace
>the
>currently running kernel.

Thanks again.

>N.B. There is a bug that will cause a failure to re-install 
>PORTS_MODULES.
...

At this point I am not worried about kernel modules built from ports.

I just want a working version that won't seemingly randomly crash, leaving no core dump or any other relevant messages. The only thing pointing to a crash are entries in wtmp, which lastlog reports as "crash". Nothing. Else.


-- 




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