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Re: [rhelv6-list] A kernel bug that causes a system crash when the uptime is longer than 208.5 days



On Fri, Jan 6, 2012 at 8:55 AM, Robin Price II <rprice redhat com> wrote:
> Bugzilla:  https://bugzilla.redhat.com/show_bug.cgi?id=765720
>
> This is private due to private information from customer use cases.  If you
> need further details, I would highly encourage you to contact Red Hat
> support or your TAM.
>
> Here is the initial information opened in the BZ:
>
> "The following patch is in urgent fix for Linus branch, which avoid the
> unnecessary overflow in sched_clock otherwise kernel will crash after
> 209~250 days.
>
> http://git.kernel.org/?p=linux/kernel/git/tip/tip.git;a=patch;h=4cecf6d401a01d054afc1e5f605bcbfe553cb9b9
>
> In hundreds of days, the __cycles_2_ns calculation in sched_clock
> has an overflow.  cyc * per_cpu(cyc2ns, cpu) exceeds 64 bits, causing the
> final value to become zero.  We can solve this without losing any precision.
> We can decompose TSC into quotient and remainder of division by the scale
> factor, and then use this to convert TSC into nanoseconds."
>
> ~rp

Thank you for this post to let us know that Red Hat is now taking care
of this issue.

Akemi


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