[Hardy] SRU: Fix boot panic on Acer Aspire One
Tim Gardner
tim.gardner at canonical.com
Mon Jul 13 19:59:04 UTC 2009
Stefan Bader wrote:
> SRU Justification:
>
> Impact: Certain kernel versions cause a kernel panic on the Acer Aspire
> One when the kernel changes its data to read-only pages. The underlying
> problem is very timing sensitive (adding printks for debugging makes the
> problem much less likely to occur).
>
> Fix: As far as we understand, there might be another thread being
> running (with a very speculative maybe related to freeing init memory)
> which gets badly confused by the global_flush_tlb() (could also be
> affected by the fact that changing the page attributes splits a large
> kernel page). To prevent that we force all other CPUs to run the stop
> work function, which basically acts like a big sync. The performance
> impact is minimal as this is done only once on boot.
>
> Testcase: Booting testkernel on the Acer Aspire One and for comparison
> on a Dell Inspiron 1521. The Acer succeeds in rebooting without panic
> and the Dell still does the same.
>
> --
>
> When all other means of communication fail, try words!
>
>
NACK - Shouldn't this be quirked for the Acer platform? I think this
looks like a total hack and has global i386 impact.
--
Tim Gardner tim.gardner at canonical.com
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