Messages in this thread | | | Date | Tue, 15 Jan 2013 13:38:13 -0500 | From | Rik van Riel <> | Subject | Re: [RFCv3][PATCH 2/3] fix kvm's use of __pa() on percpu areas |
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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 <riel@redhat.com>
-- All rights reversed
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