[gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Nikos Chantziaras]

Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if you're 
using the EXT4 filesystem:

http://www.phoronix.com/scan.php?page=news_item&px=MTIxNDQ

This includes gentoo-sources.  I hope the Gentoo developers are on top 
of this.  In the meantime, avoid doing reboots after too short an uptime.

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Dale]

Nikos Chantziaras wrote:
> Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if
> you're using the EXT4 filesystem:
>
> http://www.phoronix.com/scan.php?page=news_item&px=MTIxNDQ
>
> This includes gentoo-sources.  I hope the Gentoo developers are on top
> of this.  In the meantime, avoid doing reboots after too short an uptime.
>
>
>

Oh crap.  O_O 

This is one of those times I am glad I am not a shutdown/restart nut.  lol 

root@fireball / # uptime
 09:39:19 up 32 days,  1:48,  5 users,  load average: 0.35, 0.35, 0.44
root@fireball / #

Should be safe enough by now.  I wonder what version will have the fix
tho?  3.7?  3.8?  They move pretty quick tho.  That's good. 

Thanks for the heads up. 

Dale, not going to panic yet. 

:-)  :-) 

-- 
I am only responsible for what I said ... Not for what you understood or how you interpreted my words!

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[covici]

Dale <rdalek1967@gmail.com> wrote:

> Nikos Chantziaras wrote:
> > Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if
> > you're using the EXT4 filesystem:
> >
> > http://www.phoronix.com/scan.php?page=news_item&px=MTIxNDQ
> >
> > This includes gentoo-sources.  I hope the Gentoo developers are on top
> > of this.  In the meantime, avoid doing reboots after too short an uptime.
> >
> >
> >
> 
> Oh crap.  O_O 
> 
> This is one of those times I am glad I am not a shutdown/restart nut.  lol 
> 
> root@fireball / # uptime
>  09:39:19 up 32 days,  1:48,  5 users,  load average: 0.35, 0.35, 0.44
> root@fireball / #
> 
> Should be safe enough by now.  I wonder what version will have the fix
> tho?  3.7?  3.8?  They move pretty quick tho.  That's good. 
> 
> Thanks for the heads up. 
> 
> Dale, not going to panic yet. 
> 
> :-)  :-) 
> 
> -- 
> I am only responsible for what I said ... Not for what you understood or how you interpreted my words!
> 
What git tree is this -- maybe I can get the diff and reverse patch till
a newer version comes out?


-- 
Your life is like a penny.  You're going to lose it.  The question is:
How do
you spend it?

         John Covici
         covici@ccs.covici.com

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Paul Hartman]

On Wed, Oct 24, 2012 at 8:54 AM, Nikos Chantziaras <realnc@gmail.com> wrote:
> Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if you're
> using the EXT4 filesystem:
>
> http://www.phoronix.com/scan.php?page=news_item&px=MTIxNDQ
>
> This includes gentoo-sources.  I hope the Gentoo developers are on top of
> this.  In the meantime, avoid doing reboots after too short an uptime.

Thanks, I was just about to upgrade to latest! I'm currently still on
3.5.4 which appears to not include the bad code. Looks like 3.5.7 is
first affected version in the 3.5.x series.

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Markos Chandras]

On Wed, Oct 24, 2012 at 2:54 PM, Nikos Chantziaras <realnc@gmail.com> wrote:
> Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if you're
> using the EXT4 filesystem:
>
> http://www.phoronix.com/scan.php?page=news_item&px=MTIxNDQ
>
> This includes gentoo-sources.  I hope the Gentoo developers are on top of
> this.  In the meantime, avoid doing reboots after too short an uptime.
>
>

https://bugs.gentoo.org/show_bug.cgi?id=439502

-- 
Regards,
Markos Chandras / Gentoo Linux Developer / Key ID: B4AFF2C2

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Bruce Hill]

On Wed, Oct 24, 2012 at 04:54:39PM +0300, Nikos Chantziaras wrote:
> Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if you're 
> using the EXT4 filesystem:
> 
> http://www.phoronix.com/scan.php?page=news_item&px=MTIxNDQ
> 
> This includes gentoo-sources.  I hope the Gentoo developers are on top 
> of this.  In the meantime, avoid doing reboots after too short an uptime.

https://bugs.gentoo.org/show_bug.cgi?id=439502
-- 
Happy Penguin Computers               >')
126 Fenco Drive                       ( \
Tupelo, MS 38801                       ^^
support@happypenguincomputers.com
662-269-2706 662-205-6424
http://happypenguincomputers.com/

Don't top-post: http://en.wikipedia.org/wiki/Top_post#Top-posting

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[john]

On Wed, 24 Oct 2012 13:10:24 -0500
Bruce Hill <daddy@happypenguincomputers.com> wrote:

> On Wed, Oct 24, 2012 at 04:54:39PM +0300, Nikos Chantziaras wrote:
> > Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if
> > you're using the EXT4 filesystem:
> > 
> > http://www.phoronix.com/scan.php?page=news_item&px=MTIxNDQ
> > 
> > This includes gentoo-sources.  I hope the Gentoo developers are on
> > top of this.  In the meantime, avoid doing reboots after too short
> > an uptime.
> 
> https://bugs.gentoo.org/show_bug.cgi?id=439502

I shall think myself lucky. Converted the
majority of my file systems (var home) on laptop, desktop and qemu to
ext4 a few weeks ago and was rebooting like crazy last night on 3.5.7.
with my desktop after losing ptys, network and keyboard when downgrading
openrc.

Shall reverse and make sure backups are in place. 

Thanks for the warning. I would hate to lose my xpenguins program

-- 
John D Maunder

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[mindrunner]

affected kernel versions are masked now!

On 10/25/2012 12:36 AM, john wrote:
> On Wed, 24 Oct 2012 13:10:24 -0500
> Bruce Hill <daddy@happypenguincomputers.com> wrote:
> 
>> On Wed, Oct 24, 2012 at 04:54:39PM +0300, Nikos Chantziaras wrote:
>>> Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if
>>> you're using the EXT4 filesystem:
>>>
>>> http://www.phoronix.com/scan.php?page=news_item&px=MTIxNDQ
>>>
>>> This includes gentoo-sources.  I hope the Gentoo developers are on
>>> top of this.  In the meantime, avoid doing reboots after too short
>>> an uptime.
>>
>> https://bugs.gentoo.org/show_bug.cgi?id=439502
> 
> I shall think myself lucky. Converted the
> majority of my file systems (var home) on laptop, desktop and qemu to
> ext4 a few weeks ago and was rebooting like crazy last night on 3.5.7.
> with my desktop after losing ptys, network and keyboard when downgrading
> openrc.
> 
> Shall reverse and make sure backups are in place. 
> 
> Thanks for the warning. I would hate to lose my xpenguins program
> 

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Canek Peláez Valdés]

On Wed, Oct 24, 2012 at 8:54 AM, Nikos Chantziaras <realnc@gmail.com> wrote:
> Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if you're
> using the EXT4 filesystem:
>
> http://www.phoronix.com/scan.php?page=news_item&px=MTIxNDQ
>
> This includes gentoo-sources.  I hope the Gentoo developers are on top of
> this.  In the meantime, avoid doing reboots after too short an uptime.

Doesn't seem to be that serious:

https://plus.google.com/u/0/117091380454742934025/posts/Wcc5tMiCgq7

Regards.
-- 
Canek Peláez Valdés
Posgrado en Ciencia e Ingeniería de la Computación
Universidad Nacional Autónoma de México

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Kerin Millar]

Canek Peláez Valdés wrote:
> On Wed, Oct 24, 2012 at 8:54 AM, Nikos Chantziaras<realnc@gmail.com>  wrote:
>> Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if you're
>> using the EXT4 filesystem:
>>
>> http://www.phoronix.com/scan.php?page=news_item&px=MTIxNDQ
>>
>> This includes gentoo-sources.  I hope the Gentoo developers are on top of
>> this.  In the meantime, avoid doing reboots after too short an uptime.
>
> Doesn't seem to be that serious:
>
> https://plus.google.com/u/0/117091380454742934025/posts/Wcc5tMiCgq7

Might I enquire as to the manner in which this comment impartially 
establishes that the consequences of the bug upon those affected is not 
serious?

--Kerin

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Canek Peláez Valdés]

On Wed, Oct 24, 2012 at 8:09 PM, Kerin Millar <kerframil@fastmail.co.uk> wrote:
> Canek Peláez Valdés wrote:
>>
>> On Wed, Oct 24, 2012 at 8:54 AM, Nikos Chantziaras<realnc@gmail.com>
>> wrote:
>>>
>>> Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if you're
>>> using the EXT4 filesystem:
>>>
>>> http://www.phoronix.com/scan.php?page=news_item&px=MTIxNDQ
>>>
>>> This includes gentoo-sources.  I hope the Gentoo developers are on top of
>>> this.  In the meantime, avoid doing reboots after too short an uptime.
>>
>>
>> Doesn't seem to be that serious:
>>
>> https://plus.google.com/u/0/117091380454742934025/posts/Wcc5tMiCgq7
>
>
> Might I enquire as to the manner in which this comment impartially
> establishes that the consequences of the bug upon those affected is not
> serious?

"I suppose I should be glad the potential ext4 corruption that two
users have reported potentially impacting v3.6.2 and v3.6.3 has
promoted some minor increase in revenue (due to advertising hits) for
Slashdot and Phoronix, but really, people should chill out."

"That's not to say that we're not treating this seriously; I was up
until late last night trying to get a handle on it.  But folks
shouldn't be running around with their heads cut off. "

"It now looks like the reproduction involved something very esoteric
indeed, involving using umount -l and shutdowns while the file system
was still being unmounted --- and the user had nobarrier specified in
the mount options as well."

http://thread.gmane.org/gmane.linux.kernel/1379725/focus=34994

http://thread.gmane.org/gmane.linux.kernel/1379725/focus=35003

That, and the picture with the big "DON'T PANIC" letters on it.

Regards.
-- 
Canek Peláez Valdés
Posgrado en Ciencia e Ingeniería de la Computación
Universidad Nacional Autónoma de México

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Canek Peláez Valdés]

On Wed, Oct 24, 2012 at 8:09 PM, Kerin Millar <kerframil@fastmail.co.uk> wrote:
> Canek Peláez Valdés wrote:
>>
>> On Wed, Oct 24, 2012 at 8:54 AM, Nikos Chantziaras<realnc@gmail.com>
>> wrote:
>>>
>>> Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if you're
>>> using the EXT4 filesystem:
>>>
>>> http://www.phoronix.com/scan.php?page=news_item&px=MTIxNDQ
>>>
>>> This includes gentoo-sources.  I hope the Gentoo developers are on top of
>>> this.  In the meantime, avoid doing reboots after too short an uptime.
>>
>>
>> Doesn't seem to be that serious:
>>
>> https://plus.google.com/u/0/117091380454742934025/posts/Wcc5tMiCgq7
>
>
> Might I enquire as to the manner in which this comment impartially
> establishes that the consequences of the bug upon those affected is not
> serious?

Oh, and about "impartiality"; this is a technical issue, not a
philosophical one. I will always trust the expert's opinion over
almost everyone's else.

Regards.
-- 
Canek Peláez Valdés
Posgrado en Ciencia e Ingeniería de la Computación
Universidad Nacional Autónoma de México

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Kerin Millar]

Canek Peláez Valdés wrote:
> On Wed, Oct 24, 2012 at 8:09 PM, Kerin Millar<kerframil@fastmail.co.uk>  wrote:
>> Canek Peláez Valdés wrote:
>>> On Wed, Oct 24, 2012 at 8:54 AM, Nikos Chantziaras<realnc@gmail.com>
>>> wrote:
>>>> Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if you're
>>>> using the EXT4 filesystem:
>>>>
>>>> http://www.phoronix.com/scan.php?page=news_item&px=MTIxNDQ
>>>>
>>>> This includes gentoo-sources.  I hope the Gentoo developers are on top of
>>>> this.  In the meantime, avoid doing reboots after too short an uptime.
>>>
>>> Doesn't seem to be that serious:
>>>
>>> https://plus.google.com/u/0/117091380454742934025/posts/Wcc5tMiCgq7
>>
>> Might I enquire as to the manner in which this comment impartially
>> establishes that the consequences of the bug upon those affected is not
>> serious?
>
> Oh, and about "impartiality"; this is a technical issue, not a
> philosophical one. I will always trust the expert's opinion over
> almost everyone's else.
>

The comment you linked to was fairly bereft of technical content, other 
than to assert that the circumstances under which the bug triggers are 
so limited that there is no general cause for concern. Given that (a) 
the investigation chronicled by the lkml thread remains ongoing (b) a 
remedy has yet to be conclusively determined, it is illogical that any 
statement as to the scope of the bug can anything more than a hypothesis 
at best, irrespective of how well-informed said hypothesis might be.

As for impartiality, it is entirely conceivable that someone in Ted's 
position would be riled by what they perceive (not necessarily 
correctly) as negative publicity and to respond in kind. Particularly 
when one carries a burden of responsibility of the subsystem in question.

Until such time as the matter is concluded, ext4 users that value their 
data will exercise due concern, naturally. The petty sniping about 
drumming up ad-revenue and silly 4chan style image memes do not strike 
me as a constructive way in which to assuage those concerns.

Further, the notion that nobarrier is an "esoteric" option is 
questionable. In my experience, it is common practice to employ it as a 
performance-enhancing measure on systems equipped with a battery-backed 
write cache; especially MySQL servers that must contend with a heavy 
workload. One wonders what he would have made of the notion of running 
ext4 without a journal, had it not been at the behest of Google.

In summary, I maintain that his fatuous Google+ post does nothing to 
establish just why it is that those of us in the peanut gallery should 
be unconcerned as to the impact of the bug. On my part, I will continue 
to be concerned until the investigation has fully run its course.

--Kerin

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Michael Mol]

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On Wed, Oct 24, 2012 at 10:51 PM, Kerin Millar <kerframil@fastmail.co.uk>wrote:

> Canek Peláez Valdés wrote:
>
>> On Wed, Oct 24, 2012 at 8:09 PM, Kerin Millar<kerframil@fastmail.co.**uk<kerframil@fastmail.co.uk>>
>>  wrote:
>>
>>> Canek Peláez Valdés wrote:
>>>
>>>> On Wed, Oct 24, 2012 at 8:54 AM, Nikos Chantziaras<realnc@gmail.com>
>>>> wrote:
>>>>
>>>>> Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if
>>>>> you're
>>>>> using the EXT4 filesystem:
>>>>>
>>>>> http://www.phoronix.com/scan.**php?page=news_item&px=MTIxNDQ<http://www.phoronix.com/scan.php?page=news_item&px=MTIxNDQ>
>>>>>
>>>>> This includes gentoo-sources.  I hope the Gentoo developers are on top
>>>>> of
>>>>> this.  In the meantime, avoid doing reboots after too short an uptime.
>>>>>
>>>>
>>>> Doesn't seem to be that serious:
>>>>
>>>> https://plus.google.com/u/0/**117091380454742934025/posts/**Wcc5tMiCgq7<https://plus.google.com/u/0/117091380454742934025/posts/Wcc5tMiCgq7>
>>>>
>>>
>>> Might I enquire as to the manner in which this comment impartially
>>> establishes that the consequences of the bug upon those affected is not
>>> serious?
>>>
>>
>> Oh, and about "impartiality"; this is a technical issue, not a
>> philosophical one. I will always trust the expert's opinion over
>> almost everyone's else.
>>
>>
> The comment you linked to was fairly bereft of technical content, other
> than to assert that the circumstances under which the bug triggers are so
> limited that there is no general cause for concern. Given that (a) the
> investigation chronicled by the lkml thread remains ongoing (b) a remedy
> has yet to be conclusively determined, it is illogical that any statement
> as to the scope of the bug can anything more than a hypothesis at best,
> irrespective of how well-informed said hypothesis might be.
>
> As for impartiality, it is entirely conceivable that someone in Ted's
> position would be riled by what they perceive (not necessarily correctly)
> as negative publicity and to respond in kind. Particularly when one carries
> a burden of responsibility of the subsystem in question.
>
> Until such time as the matter is concluded, ext4 users that value their
> data will exercise due concern, naturally. The petty sniping about drumming
> up ad-revenue and silly 4chan style image memes do not strike me as a
> constructive way in which to assuage those concerns.
>
> Further, the notion that nobarrier is an "esoteric" option is
> questionable. In my experience, it is common practice to employ it as a
> performance-enhancing measure on systems equipped with a battery-backed
> write cache; especially MySQL servers that must contend with a heavy
> workload. One wonders what he would have made of the notion of running ext4
> without a journal, had it not been at the behest of Google.
>
> In summary, I maintain that his fatuous Google+ post does nothing to
> establish just why it is that those of us in the peanut gallery should be
> unconcerned as to the impact of the bug. On my part, I will continue to be
> concerned until the investigation has fully run its course.
>
> --Kerin
>
>
http://lwn.net/Articles/521022/

Links to relevant analysis. Useful comments. 'nuff said.

-- 
:wq

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Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Pandu Poluan]

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On Oct 25, 2012 10:08 AM, "Michael Mol" <mikemol@gmail.com> wrote:
>
>
> http://lwn.net/Articles/521022/
>
> Links to relevant analysis. Useful comments. 'nuff said.
>
> --
> :wq

Nice find, thanks. But the update to that article which gave a link to Theo
T'so email is quite unnerving. He said that his initial hypothesis had not
been proven and he himself is back in the dark.

Not much confidence in ext4 for the time being for me. Back to reiserfs? ;-)

Rgds,
--

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Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Dale]

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Pandu Poluan wrote:
>
>
> On Oct 25, 2012 10:08 AM, "Michael Mol" <mikemol@gmail.com
> <mailto:mikemol@gmail.com>> wrote:
> >
> >
> > http://lwn.net/Articles/521022/
> >
> > Links to relevant analysis. Useful comments. 'nuff said.
> >
> > --
> > :wq
>
> Nice find, thanks. But the update to that article which gave a link to
> Theo T'so email is quite unnerving. He said that his initial
> hypothesis had not been proven and he himself is back in the dark.
>
> Not much confidence in ext4 for the time being for me. Back to
> reiserfs? ;-)
>
> Rgds,
> --
>


Or just don't update the kernel until it is fixed. After all, if the
kernel you are using works and is not a serious security problem, just
use it for a while.  They will fix it pretty soon I'm sure. 

Dale

:-)  :-) 

-- 
I am only responsible for what I said ... Not for what you understood or how you interpreted my words!


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Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Neil Bothwick]

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On Thu, 25 Oct 2012 15:10:17 -0500, Dale wrote:

> Or just don't update the kernel until it is fixed. After all, if the
> kernel you are using works and is not a serious security problem, just
> use it for a while.  They will fix it pretty soon I'm sure. 

Several versions are affected, it's not a new issue, just a newly
discovered one. That in itself indicates the likelihood of being affected
by it, considering how many boxes use ext4 with these kernel versions.


-- 
Neil Bothwick

But I thought YOU did the backups...

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Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Dale]

Neil Bothwick wrote:
> On Thu, 25 Oct 2012 15:10:17 -0500, Dale wrote:
>
>> Or just don't update the kernel until it is fixed. After all, if the
>> kernel you are using works and is not a serious security problem, just
>> use it for a while.  They will fix it pretty soon I'm sure. 
> Several versions are affected, it's not a new issue, just a newly
> discovered one. That in itself indicates the likelihood of being affected
> by it, considering how many boxes use ext4 with these kernel versions.
>
>

My point is, if you are using a version that is not affected, keep using
it, don't upgrade yet.  I saw a list of the affected versions.  Just
avoid those for now.  Is it a perfect plan, of course not.  It's better
than nothing tho.  It's certainly better than using a known version with
this problem.  If a person is using an affected version, then I would
reboot to another kernel that is not on the list. 

Now if someone wants to keep using a known version that is affected,
that's their thing.  Since I don't reboot much, it would likely not
affect me either way.  Thing is, I'm not going to take the chance either
way.  That is of course if the problem is what I read and not something
else all together.  The problem seems to be a moving target since it is
not exactly known yet.

Either way, having the information is better than nothing.  Avoiding the
affected versions is better than nothing.  None of this may matter
depending on all sorts of things.  Me, I'm going to stick with what I am
using, that's not on the affected list so far, and wait until whatever
version has a known fix.  That's my plan for now, subject to change if
the situation changes. 

Oh, going to cross fingers too. ;-) 

Dale

:-)  :-) 

-- 
I am only responsible for what I said ... Not for what you understood or how you interpreted my words!

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Volker Armin Hemmann]

Am Freitag, 26. Oktober 2012, 01:34:35 schrieb Neil Bothwick:
> On Thu, 25 Oct 2012 15:10:17 -0500, Dale wrote:
> > Or just don't update the kernel until it is fixed. After all, if the
> > kernel you are using works and is not a serious security problem, just
> > use it for a while.  They will fix it pretty soon I'm sure.
> 
> Several versions are affected, it's not a new issue, just a newly
> discovered one. That in itself indicates the likelihood of being affected
> by it, considering how many boxes use ext4 with these kernel versions.

since only two persons ever hit it, it is a pretty save bet that this bug is 
so uncommon that you should not waste any sleep over it.

-- 
#163933

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Mark Knecht]

On Sat, Oct 27, 2012 at 12:16 PM, Volker Armin Hemmann
<volkerarmin@googlemail.com> wrote:
> Am Freitag, 26. Oktober 2012, 01:34:35 schrieb Neil Bothwick:
>> On Thu, 25 Oct 2012 15:10:17 -0500, Dale wrote:
>> > Or just don't update the kernel until it is fixed. After all, if the
>> > kernel you are using works and is not a serious security problem, just
>> > use it for a while.  They will fix it pretty soon I'm sure.
>>
>> Several versions are affected, it's not a new issue, just a newly
>> discovered one. That in itself indicates the likelihood of being affected
>> by it, considering how many boxes use ext4 with these kernel versions.
>
> since only two persons ever hit it, it is a pretty save bet that this bug is
> so uncommon that you should not waste any sleep over it.
>
> --
> #163933
>

For fear of leading anyone down a path that eventually causes them
problems I won't attempt to communicate the root cause or fixes but
there is new information, and a potential patch verified by the only
person to see this problem, about what causes the corruption. Read the
thread if this makes any difference in your life. Don't worry about it
if it doesn't.

Basically, it's apparently driven by mount options and something the
OP (of the lkml thread) did which most users are unlikely IMO to ever
try.

- Mark

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Pandu Poluan]

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On Oct 26, 2012 3:14 AM, "Dale" <rdalek1967@gmail.com> wrote:
>
> Pandu Poluan wrote:
>>
>>
>> On Oct 25, 2012 10:08 AM, "Michael Mol" <mikemol@gmail.com> wrote:
>> >
>> >
>> > http://lwn.net/Articles/521022/
>> >
>> > Links to relevant analysis. Useful comments. 'nuff said.
>> >
>> > --
>> > :wq
>>
>> Nice find, thanks. But the update to that article which gave a link to
Theo T'so email is quite unnerving. He said that his initial hypothesis had
not been proven and he himself is back in the dark.
>>
>> Not much confidence in ext4 for the time being for me. Back to reiserfs?
;-)
>>
>> Rgds,
>> --
>
>
>
> Or just don't update the kernel until it is fixed. After all, if the
kernel you are using works and is not a serious security problem, just use
it for a while.  They will fix it pretty soon I'm sure.
>

Unfortunately, since Ted T'so himself couldn't even pinpoint what's wrong,
how can I be sure that other kernel versions are unaffected?

Rgds,
--

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Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Dale]

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Pandu Poluan wrote:
>
>
> On Oct 26, 2012 3:14 AM, "Dale" <rdalek1967@gmail.com
> <mailto:rdalek1967@gmail.com>> wrote:
> >
> > Pandu Poluan wrote:
> >>
> >>
> >> On Oct 25, 2012 10:08 AM, "Michael Mol" <mikemol@gmail.com
> <mailto:mikemol@gmail.com>> wrote:
> >> >
> >> >
> >> > http://lwn.net/Articles/521022/
> >> >
> >> > Links to relevant analysis. Useful comments. 'nuff said.
> >> >
> >> > --
> >> > :wq
> >>
> >> Nice find, thanks. But the update to that article which gave a link
> to Theo T'so email is quite unnerving. He said that his initial
> hypothesis had not been proven and he himself is back in the dark.
> >>
> >> Not much confidence in ext4 for the time being for me. Back to
> reiserfs? ;-)
> >>
> >> Rgds,
> >> --
> >
> >
> >
> > Or just don't update the kernel until it is fixed. After all, if the
> kernel you are using works and is not a serious security problem, just
> use it for a while.  They will fix it pretty soon I'm sure. 
> >
>
> Unfortunately, since Ted T'so himself couldn't even pinpoint what's
> wrong, how can I be sure that other kernel versions are unaffected?
>
> Rgds,
> --
>


Well, sometimes you just have to go with what you know.  I saw a list of
the versions that are affected so I would avoid those at least.  This
could be one of those times where a older kernel may be a good idea.  ;-) 

Dale

:-)  :-) 

-- 
I am only responsible for what I said ... Not for what you understood or how you interpreted my words!


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Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Mark Knecht]

On Thu, Oct 25, 2012 at 12:40 PM, Pandu Poluan <pandu@poluan.info> wrote:
<SNIP>
>
> Nice find, thanks. But the update to that article which gave a link to Theo
> T'so email is quite unnerving. He said that his initial hypothesis had not
> been proven and he himself is back in the dark.
>
> Not much confidence in ext4 for the time being for me. Back to reiserfs? ;-)
>
> Rgds,
> --

I'm not an ext4 user (it's too new!) and therefore unaffected by any
of this personally. However I do read lkml and have been following the
thread since it started. This bug, if indeed in the end it's even
determined to be a bug, is apparently pretty hard to hit. The downside
is that if you did hit it the effects can be pretty devastating.

I'd suggest folks consider going through the thread and not
overreacting to the masking of new kernels or stuff posted on Phoronix
or slashdot. It's good that the info is out there so people can make
informed decisions, but one of the downsides of having all the info is
the potential for people to overreact. Even with a ;-) dumping ext4
for Reiserfs might be in that camp. :-)

Cheers,
Mark

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Pandu Poluan]

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On Oct 26, 2012 3:36 AM, "Mark Knecht" <markknecht@gmail.com> wrote:
>
> On Thu, Oct 25, 2012 at 12:40 PM, Pandu Poluan <pandu@poluan.info> wrote:
> <SNIP>
> >
> > Nice find, thanks. But the update to that article which gave a link to
Theo
> > T'so email is quite unnerving. He said that his initial hypothesis had
not
> > been proven and he himself is back in the dark.
> >
> > Not much confidence in ext4 for the time being for me. Back to
reiserfs? ;-)
> >
> > Rgds,
> > --
>
> I'm not an ext4 user (it's too new!) and therefore unaffected by any
> of this personally. However I do read lkml and have been following the
> thread since it started. This bug, if indeed in the end it's even
> determined to be a bug, is apparently pretty hard to hit. The downside
> is that if you did hit it the effects can be pretty devastating.
>
> I'd suggest folks consider going through the thread and not
> overreacting to the masking of new kernels or stuff posted on Phoronix
> or slashdot. It's good that the info is out there so people can make
> informed decisions, but one of the downsides of having all the info is
> the potential for people to overreact. Even with a ;-) dumping ext4
> for Reiserfs might be in that camp. :-)
>
> Cheers,
> Mark
>

LoL... I was just joking about dumping ext4. I still am going to use ext4,
but I will ratchet up the backup schedule, and anyone thinking of
restarting a Linux server in my office before first performing a full
backup, will be severely reprimanded.

(I *do* use ReiserFS, though. Especially for portage's tmp)

Rgds,
--

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Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Michael Mol]

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On Thu, Oct 25, 2012 at 3:40 PM, Pandu Poluan <pandu@poluan.info> wrote:

>
> On Oct 25, 2012 10:08 AM, "Michael Mol" <mikemol@gmail.com> wrote:
> >
> >
> > http://lwn.net/Articles/521022/
> >
> > Links to relevant analysis. Useful comments. 'nuff said.
> >
> > --
> > :wq
>
> Nice find, thanks.
>

They have an RSS feed. Good stuff. I heard about this before it hit
Slashdot or Phoronix. The subscriber stuff is _truly_ good.


> But the update to that article which gave a link to Theo T'so email is
> quite unnerving. He said that his initial hypothesis had not been proven
> and he himself is back in the dark.
>
> Not much confidence in ext4 for the time being for me. Back to reiserfs?
> ;-)
>
Consider the trillions of operational hours of ext4 without
incident...you're just trolling.

-- 
:wq

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Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Pandu Poluan]

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On Oct 26, 2012 6:14 AM, "Michael Mol" <mikemol@gmail.com> wrote:
>
> On Thu, Oct 25, 2012 at 3:40 PM, Pandu Poluan <pandu@poluan.info> wrote:
>>
>>
>> On Oct 25, 2012 10:08 AM, "Michael Mol" <mikemol@gmail.com> wrote:
>> >
>> >
>> > http://lwn.net/Articles/521022/
>> >
>> > Links to relevant analysis. Useful comments. 'nuff said.
>> >
>> > --
>> > :wq
>>
>> Nice find, thanks.
>
>
> They have an RSS feed. Good stuff. I heard about this before it hit
Slashdot or Phoronix. The subscriber stuff is _truly_ good.
>

Thanks!

>>
>> But the update to that article which gave a link to Theo T'so email is
quite unnerving. He said that his initial hypothesis had not been proven
and he himself is back in the dark.
>>
>> Not much confidence in ext4 for the time being for me. Back to reiserfs?
;-)
>
> Consider the trillions of operational hours of ext4 without
incident...you're just trolling.
>

I plead guilty, your honor :-P

Okay, I'm not serious about dumping ext4 for ReiserFS. But my confidence is
still shaken. I'm going to implement a more severe watch+backup strategy
for all ext4 partitions.

Rgds,
--

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Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Canek Peláez Valdés]

On Wed, Oct 24, 2012 at 9:51 PM, Kerin Millar <kerframil@fastmail.co.uk> wrote:
[snip]
> On my part, I will continue to be concerned until the investigation has fully run its course.

That is, of course, your prerogative. I just posted a comment from
someone that (IMHO) actually knows what he's talking about. What
anyone in this list does with that information, it's their problem.

Regards.
-- 
Canek Peláez Valdés
Posgrado en Ciencia e Ingeniería de la Computación
Universidad Nacional Autónoma de México

[gentoo-user] Re: Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Nikos Chantziaras]

On 25/10/12 06:04, Canek Peláez Valdés wrote:
> On Wed, Oct 24, 2012 at 9:51 PM, Kerin Millar <kerframil@fastmail.co.uk> wrote:
> [snip]
>> On my part, I will continue to be concerned until the investigation has fully run its course.
>
> That is, of course, your prerogative. I just posted a comment from
> someone that (IMHO) actually knows what he's talking about. What
> anyone in this list does with that information, it's their problem.

What people here are doing is being careful exactly because they don't 
know what's happening.  Being careful does not equal panicking.  Not 
being careful when there's possible danger is just as bad as panicking.

[gentoo-user] Re: Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Grant Edwards]

On 2012-10-25, Kerin Millar <kerframil@fastmail.co.uk> wrote:

> The comment you linked to was fairly bereft of technical content,

That "comment" was from _Ted_Ts'o_ for pete's sake.

When Ted T'so blows his nose, it's full of technical content.

-- 
Grant Edwards               grant.b.edwards        Yow! ... If I had heart
                                  at               failure right now,
                              gmail.com            I couldn't be a more
                                                   fortunate man!!

[gentoo-user] Re: Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Remy Blank]

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Grant Edwards wrote:
> That "comment" was from _Ted_Ts'o_ for pete's sake.
> 
> When Ted T'so blows his nose, it's full of technical content.

That just made my day. Thanks :)

-- Remy


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Re: [gentoo-user] Re: Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Kerin Millar]

Grant Edwards wrote:
> On 2012-10-25, Kerin Millar<kerframil@fastmail.co.uk>  wrote:
>
>> The comment you linked to was fairly bereft of technical content,
>
> That "comment" was from _Ted_Ts'o_ for pete's sake.

I don't care it was from the heavens upon high. The only remark that was 
meaningful in a technical sense was the thoroughly inconclusive 
"Update", suggesting (but not establishing) that it might be related to 
certain combinations of mount options. The rest was just hand-waving 
about how it couldn't be a big deal because, if it was, "lots of people 
would have been complaining", which is denying the antecedent.

Let's separate two fundamental issues here. One issue is that of data 
corruption, which is a big deal. I'm sure most of us would agree on that 
point. That such an issue is going to generate news - and no small 
degree of discussion - is a given. People will want to know what the 
problem is and what they can do about it in order to be safe. What did 
Ted expect?

The second issue is that of the scope of the bug. This is where I took 
issue with the comment. The overall meaning of his comment could be 
interpreted as "Your collective concerns are overblown because the scope 
of this bug is minimal. Oh, and I think it may have something to do with 
these mount options which, being esoteric, nobody in their right mind 
would be using anyway so, hey, big deal."

The fact of the matter is that the investigation, even as I write this, 
is ongoing and no patch has been produced. Consider that for a moment. 
It doesn't matter how brilliant Ted is, or that you have seen fit to 
sample his mucus. Telling us all that we should be unconcerned because 
the scope is minimal *before* he and his peers have completed their 
investigation and a line been drawn under the affair was simply premature.

That the bug reporter has since demonstrated that the corruption can 
occur in kernel versions that don't include commit eeecef0af5 - kernels 
which we were previously told were not affected - only serves to 
demonstrate this point.

--Kerin

Re: [gentoo-user] Re: Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Volker Armin Hemmann]

Am Donnerstag, 25. Oktober 2012, 22:04:12 schrieb Kerin Millar:
> Grant Edwards wrote:
> > On 2012-10-25, Kerin Millar<kerframil@fastmail.co.uk>  wrote:
> >> The comment you linked to was fairly bereft of technical content,
> > 
> > That "comment" was from _Ted_Ts'o_ for pete's sake.
> 
> I don't care it was from the heavens upon high. The only remark that was
> meaningful in a technical sense was the thoroughly inconclusive
> "Update", suggesting (but not establishing) that it might be related to
> certain combinations of mount options. The rest was just hand-waving
> about how it couldn't be a big deal because, if it was, "lots of people
> would have been complaining", which is denying the antecedent.
> 
> Let's separate two fundamental issues here. One issue is that of data
> corruption, which is a big deal. I'm sure most of us would agree on that
> point. That such an issue is going to generate news - and no small
> degree of discussion - is a given. People will want to know what the
> problem is and what they can do about it in order to be safe. What did
> Ted expect?
> 
> The second issue is that of the scope of the bug. This is where I took
> issue with the comment. The overall meaning of his comment could be
> interpreted as "Your collective concerns are overblown because the scope
> of this bug is minimal. Oh, and I think it may have something to do with
> these mount options which, being esoteric, nobody in their right mind
> would be using anyway so, hey, big deal."
> 
> The fact of the matter is that the investigation, even as I write this,
> is ongoing and no patch has been produced. Consider that for a moment.
> It doesn't matter how brilliant Ted is, or that you have seen fit to
> sample his mucus. Telling us all that we should be unconcerned because
> the scope is minimal *before* he and his peers have completed their
> investigation and a line been drawn under the affair was simply premature.
> 
> That the bug reporter has since demonstrated that the corruption can
> occur in kernel versions that don't include commit eeecef0af5 - kernels
> which we were previously told were not affected - only serves to
> demonstrate this point.
> 

and that ONLY two people who did some REALLY stupid stuff to stumble over that 
bug are hit by it, should tell you something. For fucks sake, if you had read 
the thread, even google uses ext4 and they did not hit it. So much about its 
likelyhood.

Bugs happen. And this bug is so not a problem.

-- 
#163933

Re: [gentoo-user] Re: Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Canek Peláez Valdés]

On Sat, Oct 27, 2012 at 1:19 PM, Volker Armin Hemmann
<volkerarmin@googlemail.com> wrote:
[snip]
> and that ONLY two people who did some REALLY stupid stuff to stumble over that
> bug are hit by it, should tell you something.

Actually, it seems only *one* person can reliably reproduce this bug:

https://plus.google.com/u/0/117091380454742934025/posts/f5a1eHxUzSh

"The problem is no one other than one person who is using non-standard
mount options (which I should have disabled by default, because they
are known to be problematic) has been able to reliably reproduce the
problem."

But there is a lot of news sites who'll never miss a chance to scream
that the sky is falling. I don't think we'll see this last update from
Ted neither on Slashdot nor in Phoronix.

Regards.
-- 
Canek Peláez Valdés
Posgrado en Ciencia e Ingeniería de la Computación
Universidad Nacional Autónoma de México

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Helmut Jarausch]

On 10/24/2012 03:54:39 PM, Nikos Chantziaras wrote:
> Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if  
> you're using the EXT4 filesystem:

It looks as if Eric Sandeen has found the culprit and Theodore Ts'o has  
suggested this patch yesterday
https://lkml.org/lkml/2012/10/28/309

Helmut.

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Kerin Millar]

Helmut Jarausch wrote:
> On 10/24/2012 03:54:39 PM, Nikos Chantziaras wrote:
>> Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if
>> you're using the EXT4 filesystem:
>
> It looks as if Eric Sandeen has found the culprit and Theodore Ts'o has
> suggested this patch yesterday
> https://lkml.org/lkml/2012/10/28/309
>
> Helmut.
>

Here's the final patch:

https://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=ffb5387

It turns out to have had nothing to do with nobarrier.

--Kerin

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Dale]

Kerin Millar wrote:
> Helmut Jarausch wrote:
>> On 10/24/2012 03:54:39 PM, Nikos Chantziaras wrote:
>>> Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if
>>> you're using the EXT4 filesystem:
>>
>> It looks as if Eric Sandeen has found the culprit and Theodore Ts'o has
>> suggested this patch yesterday
>> https://lkml.org/lkml/2012/10/28/309
>>
>> Helmut.
>>
>
> Here's the final patch:
>
> https://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=ffb5387
>
>
> It turns out to have had nothing to do with nobarrier.
>
> --Kerin
>
>


Could you explain a little on who it could have affected?  Is it more
serious or less serious than originally thought?  This is for those of
us who don't subscribe to the kernel mailing list, which I have read is
hugely active. 

Thanks much.

Dale

:-)  :-) 

-- 
I am only responsible for what I said ... Not for what you understood or how you interpreted my words!

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Michael Mol]

On Fri, Nov 2, 2012 at 10:55 AM, Dale <rdalek1967@gmail.com> wrote:
> Kerin Millar wrote:
>> Helmut Jarausch wrote:
>>> On 10/24/2012 03:54:39 PM, Nikos Chantziaras wrote:
>>>> Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if
>>>> you're using the EXT4 filesystem:
>>>
>>> It looks as if Eric Sandeen has found the culprit and Theodore Ts'o has
>>> suggested this patch yesterday
>>> https://lkml.org/lkml/2012/10/28/309
>>>
>>> Helmut.
>>>
>>
>> Here's the final patch:
>>
>> https://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=ffb5387
>>
>>
>> It turns out to have had nothing to do with nobarrier.
>>
>> --Kerin
>>
>>
>
>
> Could you explain a little on who it could have affected?  Is it more
> serious or less serious than originally thought?  This is for those of
> us who don't subscribe to the kernel mailing list, which I have read is
> hugely active.
>
> Thanks much.

Well, it fixes a bug introduced in early February. If your kernel is
older than that, you're probably not affected.

More specific than that...it's a race condition that's unlikely to
affect machines that aren't creating many new files while shutting
down where the ext4 filesystem isn't being unmounted cleanly.

It's probably worth getting patched, but I'd wait until the relevant
kernel version's ebuild hits stable, same as usual.

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Paul Hartman]

On Fri, Nov 2, 2012 at 9:55 AM, Dale <rdalek1967@gmail.com> wrote:
> Kerin Millar wrote:
>> Helmut Jarausch wrote:
>>> On 10/24/2012 03:54:39 PM, Nikos Chantziaras wrote:
>>>> Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if
>>>> you're using the EXT4 filesystem:
>>>
>>> It looks as if Eric Sandeen has found the culprit and Theodore Ts'o has
>>> suggested this patch yesterday
>>> https://lkml.org/lkml/2012/10/28/309
>>>
>>> Helmut.
>>>
>>
>> Here's the final patch:
>>
>> https://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=ffb5387
>>
>>
>> It turns out to have had nothing to do with nobarrier.
>>
>> --Kerin
>>
>>
>
>
> Could you explain a little on who it could have affected?  Is it more
> serious or less serious than originally thought?  This is for those of
> us who don't subscribe to the kernel mailing list, which I have read is
> hugely active.
>
> Thanks much.

AFAIK they originally thought it was related to normal reboots after
short uptime, which would potentially put all ext4 users at risk who
use newer kernels. That is when the news stories came out about the
disastrous ext4 bug. As it turns it, it seems to have been related to
enabling some combination of experimental, non-default mount options
with an unsafe shutdown cherry on top. So the number of people who are
using that would be far, far fewer than they originally thought. Still
a dangerous bug for those people, of course, but I would guess
probably 99+ percent of ext4 users weren't at risk from it.

That is my layman's understanding, I probably got it all wrong.
Experts, feel free to correct me. :)

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Kerin Millar]

Dale wrote:
> Kerin Millar wrote:
>> Helmut Jarausch wrote:
>>> On 10/24/2012 03:54:39 PM, Nikos Chantziaras wrote:
>>>> Kernels 3.4, 3.5, and 3.6 can result in severe data corruption if
>>>> you're using the EXT4 filesystem:
>>> It looks as if Eric Sandeen has found the culprit and Theodore Ts'o has
>>> suggested this patch yesterday
>>> https://lkml.org/lkml/2012/10/28/309
>>>
>>> Helmut.
>>>
>> Here's the final patch:
>>
>> https://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=ffb5387
>>
>>
>> It turns out to have had nothing to do with nobarrier.
>>
>> --Kerin
>>
>>
>
>
> Could you explain a little on who it could have affected?  Is it more
> serious or less serious than originally thought?  This is for those of
> us who don't subscribe to the kernel mailing list, which I have read is
> hugely active.

I would describe the bug itself as serious but it will affect few users 
because journal_checksum isn't enabled by default. Ted submitted a patch 
to enable the option by default back in 2009 but it was reverted a few 
months later by Linus due to this bug:

https://bugzilla.kernel.org/show_bug.cgi?id=14354

I'm pretty sure that it hasn't since been re-enabled as a default. As 
long as you haven't enabled this option, you shouldn't have anything to 
worry about.

--Kerin

Re: [gentoo-user] Heads-up: Several kernel versions have severe EXT4 data corruption bug

[Dale]

Kerin Millar wrote:
>
> I would describe the bug itself as serious but it will affect few
> users because journal_checksum isn't enabled by default. Ted submitted
> a patch to enable the option by default back in 2009 but it was
> reverted a few months later by Linus due to this bug:
>
> https://bugzilla.kernel.org/show_bug.cgi?id=14354
>
> I'm pretty sure that it hasn't since been re-enabled as a default. As
> long as you haven't enabled this option, you shouldn't have anything
> to worry about.
>
> --Kerin
>
>

This sounds good.  At least it didn't hit to many systems since most
likely use defaults anyway, me included. 

Thanks to Michael and Paul for their replies too.  Now others know what
it turned out to be and what, if any, effect it could have on the
average user. 

Dale

:-)  :-) 

-- 
I am only responsible for what I said ... Not for what you understood or how you interpreted my words!