On Tue, May 09, 2017 at 06:02:49AM -0700, Andrew Lutomirski wrote: > On Mon, May 8, 2017 at 8:34 AM, Dave Hansen <dave.han...@intel.com> wrote: > > On 05/07/2017 05:38 AM, Andy Lutomirski wrote: > >> diff --git a/mm/rmap.c b/mm/rmap.c > >> index f6838015810f..2e568c82f477 100644 > >> --- a/mm/rmap.c > >> +++ b/mm/rmap.c > >> @@ -579,25 +579,12 @@ void page_unlock_anon_vma_read(struct anon_vma > >> *anon_vma) > >> void try_to_unmap_flush(void) > >> { > >> struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc; > >> - int cpu; > >> > >> if (!tlb_ubc->flush_required) > >> return; > >> > >> - cpu = get_cpu(); > >> - > >> - if (cpumask_test_cpu(cpu, &tlb_ubc->cpumask)) { > >> - count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL); > >> - local_flush_tlb(); > >> - trace_tlb_flush(TLB_LOCAL_SHOOTDOWN, TLB_FLUSH_ALL); > >> - } > >> - > >> - if (cpumask_any_but(&tlb_ubc->cpumask, cpu) < nr_cpu_ids) > >> - flush_tlb_others(&tlb_ubc->cpumask, NULL, 0, TLB_FLUSH_ALL); > >> - cpumask_clear(&tlb_ubc->cpumask); > >> tlb_ubc->flush_required = false; > >> tlb_ubc->writable = false; > >> - put_cpu(); > >> } > >> > >> /* Flush iff there are potentially writable TLB entries that can race > >> with IO */ > >> @@ -613,7 +600,7 @@ static void set_tlb_ubc_flush_pending(struct mm_struct > >> *mm, bool writable) > >> { > >> struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc; > >> > >> - cpumask_or(&tlb_ubc->cpumask, &tlb_ubc->cpumask, mm_cpumask(mm)); > >> + arch_tlbbatch_add_mm(&tlb_ubc->arch, mm); > >> tlb_ubc->flush_required = true; > >> > >> /* > > > > Looking at this patch in isolation, how can this be safe? It removes > > TLB flushes from the generic code. Do other patches in the series fix > > this up? > > Hmm? Unless I totally screwed this up, this patch just moves the > flushes around -- it shouldn't remove any flushes.
I think he's asking when or how arch_tlbbatch_flush gets called because it doesn't happen in try_to_unmap_flush(). -- Mel Gorman SUSE Labs