On 01/09/2013 01:59 PM, Dave Hansen wrote:
In short, it is illegal to call __pa() on an address holding a percpu variable. The times when this actually matters are pretty obscure (certain 32-bit NUMA systems), but it _does_ happen. It is important to keep KVM guests working on these systems because the real hardware is getting harder and harder to find.This bug manifested first by me seeing a plain hang at boot after this message: CPU 0 irqstacks, hard=f3018000 soft=f301a000 or, sometimes, it would actually make it out to the console: [ 0.000000] BUG: unable to handle kernel paging request at ffffffff I eventually traced it down to the KVM async pagefault code. This can be worked around by disabling that code either at compile-time, or on the kernel command-line.
Acked-by: Rik van Riel <[email protected]> -- All rights reversed -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
