Ahh! did btrfs just explode on me?

[Chris Murphy]

On Wed, Jan 21, 2015 at 1:38 PM, Neal Becker <ndbecker2 at gmail.com> wrote:
> Chris Murphy wrote:
>
>> On Wed, Jan 21, 2015 at 1:21 PM, Neal Becker <ndbecker2 at gmail.com> wrote:
>>> Chris Murphy wrote:
>>>
>>>> On Wed, Jan 21, 2015 at 12:48 PM, Neal Becker <ndbecker2 at gmail.com> wrote:
>>>>> Nice tip.  Unfortunately, btrfs --version says 3.18.  I suppose that is not
>>>>> sufficient.
>>>>
>>>> 3.18 is fine. 3.18.1 pulled in small fixes.
>>>>
>>>>
>>>>> I like this procedure, it sounds simple.  Any way to fix it?  I guess the
>>>>> btrfs was from initramfs, and that installing a newer kernel would update
>>>>> initramfs and get me btrfs 3.18.1 when booted this way?
>>>>
>>>> Yes.
>>>>
>>>>
>>>
>>> Thanks, I installed kernel 3.18.3, and followed your instructions to run
>>> btrfs check --repair from initramfs.
>>>
>>> But now that I have kernel-3.18.3 installed, I tried (fully) booting into it.
>>> Surprise, it won't boot.  Choosing it from grub, I get the usual boot
>>> progress indication, but hitting esc to show messages, all I get is a black
>>> screen.
>>> Can't switch vt.  No indication of disk activity.  Nothing found (later) in
>>> /var/log/messages about 3.18.3 - I don't think the boot got far enough.
>>>
>>> Booting up 3.17.8 works fine.
>>
>>
>> Interesting. I'm having the same problem, intermittently, with kernel
>> 3.18.3. I haven't had a chance to do much regression testing though,
>> and have since moved to 3.19 kernels which don't seem to have this
>> problem. The handful of 3.18.3 boots I've tried, it always booted with
>> nomodeset; and only intermittently failed without it. So I figured it
>> was some video regression...
>>
>> What happens if you remove 'rhgb quiet' and add 'nomodeset' parameter?
>>
>>
>
> Then I see lots of messages before it hangs.  It's not completely dead - I can
> page back through the messages.  I don't really see anything that looks like an
> error.  I got 'Welcome to Fedora 21'.

Hmm well it's not the same problem probably if you're still getting a
hang with nomodeset. It'd be nice to know for sure this is not some
Btrfs regression though, but the fact that it's hanging the console
make this difficult to troubleshoot.

Are you using 3.18.3-201? I was using 200 which doesn't contain a
backported i915 related fix that'll be in 3.18.4. But the bug it fixes
is related to video playback not a boot time video freeze. I'm not
sure what's going on yet...

Anyway you can probably safely use 3.17.8 in the short term. I still
haven't run into this bug myself using affected kernels so it's kindof
an edge case (yet nevertheless eyebrow raising since it's possible for
files to go missing, even though btrfs check repair resurrects them).


-- 
Chris Murphy