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Re: [PATCH v3 2/8] x86/mm: Change the leave_mm() condition for local TLB flushes

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On Thu, 2017-05-25 at 17:47 -0700, Andy Lutomirski wrote:
> 
> +++ b/arch/x86/mm/tlb.c
> @@ -311,7 +311,7 @@ void flush_tlb_mm_range(struct mm_struct *mm,
> unsigned long start,
>  		goto out;
>  	}
>  
> -	if (!current->mm) {
> +	if (this_cpu_read(cpu_tlbstate.state) != TLBSTATE_OK) {
>  		leave_mm(smp_processor_id());

Unless -mm changed leave_mm (I did not check), this
is not quite correct yet.

The reason is leave_mm (at least in the latest Linus
tree) ignores the cpu argument for one of its checks.

You should probably fix that in an earlier patch,
assuming you haven't already done so in -mm.

void leave_mm(int cpu)
{
        struct mm_struct *active_mm =
this_cpu_read(cpu_tlbstate.active_mm);
        if (this_cpu_read(cpu_tlbstate.state) == TLBSTATE_OK)
                BUG();
        if (cpumask_test_cpu(cpu, mm_cpumask(active_mm))) {
                cpumask_clear_cpu(cpu, mm_cpumask(active_mm));
                load_cr3(swapper_pg_dir);

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Thread

[PATCH v3 0/8] x86 TLB flush cleanups, moving toward PCID support Andy Lutomirski <luto@kernel.org> - 2017-05-26 02:50 +0200
  [PATCH v3 6/8] x86/mm: Rework lazy TLB to track the actual loaded mm Andy Lutomirski <luto@kernel.org> - 2017-05-26 02:50 +0200
  [PATCH v3 2/8] x86/mm: Change the leave_mm() condition for local TLB flushes Andy Lutomirski <luto@kernel.org> - 2017-05-26 02:50 +0200
    Re: [PATCH v3 2/8] x86/mm: Change the leave_mm() condition for  local TLB flushes Rik van Riel <riel@redhat.com> - 2017-05-26 03:40 +0200
      Re: [PATCH v3 2/8] x86/mm: Change the leave_mm() condition for local  TLB flushes Andy Lutomirski <luto@kernel.org> - 2017-05-26 04:10 +0200
        Re: [PATCH v3 2/8] x86/mm: Change the leave_mm() condition for  local TLB flushes Rik van Riel <riel@redhat.com> - 2017-05-26 15:30 +0200
    Re: [PATCH v3 2/8] x86/mm: Change the leave_mm() condition for local  TLB flushes Nadav Amit <nadav.amit@gmail.com> - 2017-05-26 03:50 +0200
  [PATCH v3 5/8] x86/mm: Remove the UP tlbflush code; always use the formerly SMP code Andy Lutomirski <luto@kernel.org> - 2017-05-26 02:50 +0200
  [PATCH v3 1/8] x86/mm: Pass flush_tlb_info to flush_tlb_others() etc Andy Lutomirski <luto@kernel.org> - 2017-05-26 02:50 +0200
  [PATCH v3 4/8] x86/mm: Use new merged flush logic in arch_tlbbatch_flush() Andy Lutomirski <luto@kernel.org> - 2017-05-26 02:50 +0200

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