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

[Michael Mol <mikemol@gmail.com>]

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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.

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:wq

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