Messages in this thread | | | Date | Sat, 25 Aug 2007 14:23:24 +0200 | From | Frederik Deweerdt <> | Subject | Re: [-mm patch] enforce noreplace-smp in alternative_instructions() |
| |
On Sat, Aug 25, 2007 at 10:07:29PM +1000, Rusty Russell wrote: > On Fri, 2007-08-24 at 10:22 +0200, Frederik Deweerdt wrote: > > [Added Gerd Hoffman and Rusty Russel to cc] > > On Thu, Aug 23, 2007 at 11:46:52PM -0700, Jeremy Fitzhardinge wrote: > > > Frederik Deweerdt wrote: > > > > That means that even when you specify noreplace_smp, some replacing > > > > takes place anyway. One of the consequences, besides noreplace_smp not > > > > working as expected, is that lguest crashes when you feed it an SMP kernel > > > > (I suspect that you can not replace alternatives for smp _and_ paravirt). > > > > > > > > > > No, that should be fine. Why does lguest crash? > > It dies with: > > [ 0.131000] SMP alternatives: switching to UP code > > lguest: bad stack page 0xc057a000 Hello Rusty, > > How odd! This means that the guest set the kernel to a stack which it > hadn't mapped writable (or perhaps not mapped at all). I always run SMP
I had time to investigate this a little further, it appears that in fact 0xc057a000 is the beginning of the __smp_locks section.
The crash responsible function call is in alternative_instructions(): free_init_pages("SMP alternatives", (unsigned long)__smp_locks, (unsigned long)__smp_locks_end);
Ie, if I comment this out, I can boot lguest without passing noreplace_smp.
BTW, to make things clear: the patch I sent does _not_ fix the lguest/alternatives problem. It just makes noreplace_smp functional again and hence allows working around the lguest/alternatives bug.
> kernels, and that seems a very strange side effect of a patching > problem... > > Nonetheless, I did have a previous problem with a bug in the patching > code which didn't show up native and did show up under lguest. > > Can you send your config? Here it is: http://fdeweerdt.free.fr/lguest_smp/dot_config
> Do you need noreplace-smp even on 2.6.23-rc3, > or only 2.6.23-rc3-mm1? I'll try ASAP.
Thanks, Frederik - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |