Messages in this thread | | | Date | Tue, 25 Aug 2009 21:24:16 +0200 | From | Ingo Molnar <> | Subject | Re: [patch] x86: 2.6.31-rc7 crash due to buggy flat_phys_pkg_id |
| |
* Yinghai Lu <yinghai@kernel.org> wrote:
> Ingo Molnar wrote: > > * Linus Torvalds <torvalds@linux-foundation.org> wrote: > > > >> On Tue, 25 Aug 2009, Yinghai Lu wrote: > >>> initial apic id and apic id could be different. > >>> > >>> and we should use initial apic id to get correct phys pkg id in > >>> case BIOS set crazy apic id. > >> Yinghai - I think you missed Cyrills' point. Let me repeat it: > >> > >> "cpu_has_apic bit turned off" > >> > >> there's no apic. No "initial apic id". No "phys pkg id". No > >> nothing. > >> > >> Discussions about "correct phys pkg id" are pointless. > > > > that's not the case here though: > > > > [ 8.713916] Total of 32 processors activated (162314.96 BogoMIPS). > > > > so APICs are active. The real difference is i think this aspect of > > commit 2759c3287: > > > > static int flat_phys_pkg_id(int initial_apic_id, int index_msb) > > { > > - return hard_smp_processor_id() >> index_msb; > > + return initial_apic_id >> index_msb; > > } > > > > We need to revert back to .30 behavior here. (In case of which > > environment to trust we almost always trust whatever booted millions > > of Linux boxes in the past already.) > > > > Furthermore, commit 2759c3287 did not declare any side-effects and > > clearly causes a side-effect on vSMP which apparently has an > > overlapping set of initial APIC ids. > > > > Ravikiran, your patch does not do a clear revert of this bit though. > > If you do a plain revert of the line above alone, does that fix the > > problem too? > > how about patch phys_pkg_id for vsmp? > > diff --git a/arch/x86/kernel/apic/probe_64.c b/arch/x86/kernel/apic/probe_64.c > index f3b1037..65edc18 100644 > --- a/arch/x86/kernel/apic/probe_64.c > +++ b/arch/x86/kernel/apic/probe_64.c > @@ -44,6 +44,11 @@ static struct apic *apic_probe[] __initdata = { > NULL, > }; > > +static int apicid_phys_pkg_id(int initial_apic_id, int index_msb) > +{ > + return hard_smp_processor_id() >> index_msb; > +} > + > /* > * Check the APIC IDs in bios_cpu_apicid and choose the APIC mode. > */ > @@ -69,6 +74,11 @@ void __init default_setup_apic_routing(void) > printk(KERN_INFO "Setting APIC routing to %s\n", apic->name); > } > > + if (is_vsmp_box()) { > + /* need to update phys_pkg_id */ > + apic->phys_pkg_id = apicid_phys_pkg_id; > + }
Hm, this is rather tempting simply because it only affects vSMP systems and we are in late -rc's. Ravikiran, does Yinghai's patch solve the crash for you too?
Ingo
| |