On Tue, Jul 18, 2017 at 1:53 AM, Ingo Molnar <mingo@xxxxxxxxxx> wrote: > > * Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > >> On Wed, Jul 05, 2017 at 09:04:39AM -0700, Andy Lutomirski wrote: >> > On Wed, Jul 5, 2017 at 5:18 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: >> > > On Thu, Jun 29, 2017 at 08:53:22AM -0700, Andy Lutomirski wrote: >> > >> @@ -104,18 +140,20 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, >> > >> >> > >> /* Resume remote flushes and then read tlb_gen. */ >> > >> cpumask_set_cpu(cpu, mm_cpumask(next)); >> > > >> > > Barriers should have a comment... what is being ordered here against >> > > what? >> > >> > How's this comment? >> > >> > /* >> > * Resume remote flushes and then read tlb_gen. We need to do >> > * it in this order: any inc_mm_tlb_gen() caller that writes a >> > * larger tlb_gen than we read here must see our cpu set in >> > * mm_cpumask() so that it will know to flush us. The barrier >> > * here synchronizes with inc_mm_tlb_gen(). >> > */ >> >> Slightly confusing, you mean this, right? >> >> >> cpumask_set_cpu(cpu, mm_cpumask()); inc_mm_tlb_gen(); >> >> MB MB >> >> next_tlb_gen = atomic64_read(&next->context.tlb_gen); flush_tlb_others(mm_cpumask()); >> >> >> which seems to make sense. > > Btw., I'll wait for a v5 iteration before applying this last patch to tip:x86/mm. I'll send it shortly. I think I'll also add a patch to factor out the flush calls a bit more to prepare for Mel's upcoming fix. > > Thanks, > > Ingo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
