On Sun, 2017-05-28 at 10:00 -0700, Andy Lutomirski wrote:
> @@ -292,61 +303,33 @@ static unsigned long
> tlb_single_page_flush_ceiling __read_mostly = 33;
> void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
> unsigned long end, unsigned long
> vmflag)
> {
> - unsigned long addr;
> - struct flush_tlb_info info;
> - /* do a global flush by default */
> - unsigned long base_pages_to_flush = TLB_FLUSH_ALL;
> -
> - preempt_disable();
> + int cpu;
>
> - if ((end != TLB_FLUSH_ALL) && !(vmflag & VM_HUGETLB))
> - base_pages_to_flush = (end - start) >> PAGE_SHIFT;
> - if (base_pages_to_flush > tlb_single_page_flush_ceiling)
> - base_pages_to_flush = TLB_FLUSH_ALL;
> -
> - if (current->active_mm != mm) {
> - /* Synchronize with switch_mm. */
> - smp_mb();
> -
> - goto out;
> - }
> -
> - if (this_cpu_read(cpu_tlbstate.state) != TLBSTATE_OK) {
> - leave_mm(smp_processor_id());
> + struct flush_tlb_info info = {
> + .mm = mm,
> + };
>
> - /* Synchronize with switch_mm. */
> - smp_mb();
> + cpu = get_cpu();
>
> - goto out;
> - }
> + /* Synchronize with switch_mm. */
> + smp_mb();
>
> - /*
> - * Both branches below are implicit full barriers (MOV to CR
> or
> - * INVLPG) that synchronize with switch_mm.
> - */
> - if (base_pages_to_flush == TLB_FLUSH_ALL) {
> - count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
> - local_flush_tlb();
> + /* Should we flush just the requested range? */
> + if ((end != TLB_FLUSH_ALL) &&
> + !(vmflag & VM_HUGETLB) &&
> + ((end - start) >> PAGE_SHIFT) <=
> tlb_single_page_flush_ceiling) {
> + info.start = start;
> + info.end = end;
> } else {
> - /* flush range by one by one 'invlpg' */
> - for (addr = start; addr < end; addr +=
> PAGE_SIZE) {
> - count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ONE);
> - __flush_tlb_single(addr);
> - }
> - }
> - trace_tlb_flush(TLB_LOCAL_MM_SHOOTDOWN,
> base_pages_to_flush);
> -out:
> - info.mm = mm;
> - if (base_pages_to_flush == TLB_FLUSH_ALL) {
> info.start = 0UL;
> info.end = TLB_FLUSH_ALL;
> - } else {
> - info.start = start;
> - info.end = end;
> }
> - if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) <
> nr_cpu_ids)
> +
> + if (mm == current->active_mm)
> + flush_tlb_func_local(&info, TLB_LOCAL_MM_SHOOTDOWN);
It looks like this could cause flush_tlb_func_local to be
called over and over again even while cpu_tlbstate.state
equals TLBSTATE_LAZY, because active_mm is not changed by
leave_mm.
Do you want to also test cpu_tlbstate.state != TLBSTATE_OK
here, to ensure flush_tlb_func_local is only called when
necessary?
> + if (cpumask_any_but(mm_cpumask(mm), cpu) < nr_cpu_ids)
> flush_tlb_others(mm_cpumask(mm), &info);
> - preempt_enable();
> + put_cpu();
> }
>
>
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