On Thursday 12/11 at 15:43 +0100, Borislav Petkov wrote: > On Wed, Dec 10, 2014 at 06:34:38PM -0800, Calvin Owens wrote: > > This doens't fix the original issue though: the timer double-add can > > still happen if the CMCI interrupt that hits the STORM threshold pops > > off during mce_timer_fn() and calls mce_timer_kick(). > > Right, I guess we could do something similar to what you proposed > already (diff below ontop of my previous diff).
That looks good, thanks :) > > The polling is unnecessary on a CMCI-capable machine except in STORMs, > > right? Wouldn't it be better to eliminate it in that case? > > Right, the problem with error thresholding is that it only counts errors > and raises the APIC interrupt when a certain count has been reached. > But there's no way for the software to look at *each* error and try to > discover trends and stuff. > > Thus, we've been working on something which looks at each memory error, > collects them and then decays them over time and acts only for the > significant ones by poisoning pages: > > https://urldefense.proofpoint.com/v1/url?u=https://lkml.kernel.org/r/1404242623-10094-1-git-send-email-bp%40alien8.de&k=ZVNjlDMF0FElm4dQtryO4A%3D%3D%0A&r=oEb120Cp%2FehdhuY2M7qjelK5yT8IPB5WC2nEG4obDh4%3D%0A&m=Uvvje79YqtSSsaolAYcJ9N3FPGiWTIz7feUxwbhAkNc%3D%0A&s=c88a2b8458e7f07ba887d26414f2ce5b80f9180353d0895a7f4f8b47d19dbec8 > > When we have that thing in place we can probably even go a step further > and simply disable error thresholding because it simply doesn't give us > what we need. > > Btw, we would very much welcome your thoughs on this collector thing and > whether it would be usable in large installations. Or if not, what else > would it need added. Ooh I like this, I'll add some thoughts over in that thread. > > That said, I ran mce-test with your patch on top of 3.18, looks good > > there. But that doesn't simulate CMCI interrupts. > > Thanks, I had a machine here which was the perfect natural error > injector (has faulty DIMMs). I need to dig it out and play with it again > :) > > Thanks. > > --- > diff --git a/arch/x86/kernel/cpu/mcheck/mce.c > b/arch/x86/kernel/cpu/mcheck/mce.c > index e3f426698164..8cf2f486b81e 100644 > --- a/arch/x86/kernel/cpu/mcheck/mce.c > +++ b/arch/x86/kernel/cpu/mcheck/mce.c > @@ -1331,6 +1331,24 @@ int ce_error_seen(void) > return test_and_clear_bit(0, v); > } > > +static void __restart_timer(struct timer_list *t, unsigned long interval) > +{ > + unsigned long when = jiffies + interval; > + unsigned long flags; > + > + local_irq_save(flags); > + > + if (timer_pending(t)) { > + if (time_before(when, t->expires)) > + mod_timer_pinned(t, when); > + } else { > + t->expires = round_jiffies(when); > + add_timer_on(t, smp_processor_id()); > + } > + > + local_irq_restore(flags); > +} > + > static void mce_timer_fn(unsigned long data) > { > struct timer_list *t = this_cpu_ptr(&mce_timer); > @@ -1362,8 +1380,7 @@ static void mce_timer_fn(unsigned long data) > > done: > __this_cpu_write(mce_next_interval, iv); > - t->expires = jiffies + iv; > - add_timer_on(t, cpu); > + __restart_timer(t, iv); > } > > /* > @@ -1372,16 +1389,10 @@ done: > void mce_timer_kick(unsigned long interval) > { > struct timer_list *t = this_cpu_ptr(&mce_timer); > - unsigned long when = jiffies + interval; > unsigned long iv = __this_cpu_read(mce_next_interval); > > - if (timer_pending(t)) { > - if (time_before(when, t->expires)) > - mod_timer_pinned(t, when); > - } else { > - t->expires = round_jiffies(when); > - add_timer_on(t, smp_processor_id()); > - } > + __restart_timer(t, interval); > + > if (interval < iv) > __this_cpu_write(mce_next_interval, interval); > } > > -- > Regards/Gruss, > Boris. > > Sent from a fat crate under my desk. Formatting is fine. > -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
