On Mon, May 27, 2019 at 06:59:01PM +0000, Nadav Amit wrote: > > On May 27, 2019, at 2:24 AM, Peter Zijlstra <[email protected]> wrote: > > > > On Sat, May 25, 2019 at 01:22:01AM -0700, Nadav Amit wrote: > > > >> There is one functional change, which should not affect correctness: > >> flush_tlb_mm_range compared loaded_mm and the mm to figure out if local > >> flush is needed. Instead, the common code would look at the mm_cpumask() > >> which should give the same result. > > > >> @@ -786,18 +804,9 @@ void flush_tlb_mm_range(struct mm_struct *mm, > >> unsigned long start, > >> info = get_flush_tlb_info(mm, start, end, stride_shift, freed_tables, > >> new_tlb_gen); > >> > >> - if (mm == this_cpu_read(cpu_tlbstate.loaded_mm)) { > >> - lockdep_assert_irqs_enabled(); > >> - local_irq_disable(); > >> - flush_tlb_func_local(info, TLB_LOCAL_MM_SHOOTDOWN); > >> - local_irq_enable(); > >> - } > >> - > >> - if (cpumask_any_but(mm_cpumask(mm), cpu) < nr_cpu_ids) > >> - flush_tlb_others(mm_cpumask(mm), info); > > > > So if we want to double check that; we'd add: > > > > WARN_ON_ONCE(cpumask_test_cpu(smp_processor_id(), mm_cpumask(mm)) == > > (mm == this_cpu_read(cpu_tlbstate.loaded_mm))); > > > > right? > > Yes, except the condition should be inverted (“!=“ instead of “==“), and I > would prefer to use VM_WARN_ON_ONCE(). > > Unfortunately, this condition does fire when copy_init_mm() calls dup_mm(). > I don’t think there is a correctness issue, and I am tempted just check, > before warning, that (mm != init_mm) . > > What do you say?
Works for me.
