On Tue, Jul 17, 2018 at 02:35:41AM -0700, tip-bot for Rik van Riel wrote:
> diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
> index 26542cc17043..e4156e37aa71 100644
> --- a/arch/x86/mm/tlb.c
> +++ b/arch/x86/mm/tlb.c
> @@ -712,15 +712,50 @@ void tlb_flush_remove_tables_local(void *arg)
> }
> }
>
> +static void mm_fill_lazy_tlb_cpu_mask(struct mm_struct *mm,
> + struct cpumask *lazy_cpus)
> +{
> + int cpu;
> +
> + for_each_cpu(cpu, mm_cpumask(mm)) {
> + if (!per_cpu(cpu_tlbstate.is_lazy, cpu))
> + cpumask_set_cpu(cpu, lazy_cpus);
That really wants to be __cpumask_set_cpu(). Using LOCK prefix
instructions to set local bits is kinda pointless and expensive.
> + }
> +}
> +
> void tlb_flush_remove_tables(struct mm_struct *mm)
> {
> int cpu = get_cpu();
> + cpumask_var_t lazy_cpus;
> +
> + if (cpumask_any_but(mm_cpumask(mm), cpu) >= nr_cpu_ids) {
> + put_cpu();
> + return;
> + }
> +
> + if (!zalloc_cpumask_var(&lazy_cpus, GFP_ATOMIC)) {
> + /*
> + * If the cpumask allocation fails, do a brute force flush
> + * on all the CPUs that have this mm loaded.
> + */
> + smp_call_function_many(mm_cpumask(mm),
> + tlb_flush_remove_tables_local, (void *)mm, 1);
> + put_cpu();
> + return;
> + }
> +
> /*
> - * XXX: this really only needs to be called for CPUs in lazy TLB mode.
> + * CPUs with !is_lazy either received a TLB flush IPI while the user
> + * pages in this address range were unmapped, or have context switched
> + * and reloaded %CR3 since then.
> + *
> + * Shootdown IPIs at page table freeing time only need to be sent to
> + * CPUs that may have out of date TLB contents.
> */
> - if (cpumask_any_but(mm_cpumask(mm), cpu) < nr_cpu_ids)
> - smp_call_function_many(mm_cpumask(mm), tlb_flush_remove_tables_local, (void *)mm, 1);
> -
> + mm_fill_lazy_tlb_cpu_mask(mm, lazy_cpus);
> + smp_call_function_many(lazy_cpus,
> + tlb_flush_remove_tables_local, (void *)mm, 1);
> + free_cpumask_var(lazy_cpus);
> put_cpu();
> }
Also, was there a reason to re-implement on_each_cpu_cond() ? (which btw
also wants that __cpumask_set_bit fix).
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