linux-kernel - Re: [PATCH 5/7] x86,tlb: only send page table free TLB flush to lazy TLB CPUs

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Date:   Sat, 07 Jul 2018 17:21:28 -0400
From:   Rik van Riel <riel@...riel.com>
To:     Mike Galbraith <efault@....de>, linux-kernel@...r.kernel.org
Cc:     x86@...nel.org, luto@...nel.org, dave.hansen@...ux.intel.com,
        mingo@...nel.org, kernel-team@...com, tglx@...utronix.de,
        songliubraving@...com, hpa@...or.com
Subject: Re: [PATCH 5/7] x86,tlb: only send page table free TLB flush to
 lazy TLB CPUs

On Sat, 2018-07-07 at 14:26 +0200, Mike Galbraith wrote:
> On Fri, 2018-06-29 at 10:29 -0400, Rik van Riel wrote:
> > diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
> > index e59214ec52b1..c4073367219d 100644
> > --- a/arch/x86/mm/tlb.c
> > +++ b/arch/x86/mm/tlb.c
> > @@ -718,14 +718,47 @@ 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);
> > +	}
> > +}
> > +
> >  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)
> > +		return;
> 
> A put_cpu() went missing.

Doh!

Thank you for spotting that, I will fix
that in the next version!

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