Subject: Re: [PATCH v2 05/10] x86/mm: Rework lazy TLB mode and TLB freshness
 tracking
To: Andy Lutomirski <luto@kernel.org>, x86@kernel.org
References: <cover.1497415951.git.luto@kernel.org>
 <039935bc914009103fdaa6f72f14980c19562de5.1497415951.git.luto@kernel.org>
Cc: linux-kernel@vger.kernel.org, Borislav Petkov <bp@alien8.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mel Gorman <mgorman@suse.de>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        Nadav Amit <nadav.amit@gmail.com>, Rik van Riel <riel@redhat.com>,
        Arjan van de Ven <arjan@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>, Andrew Banman <abanman@sgi.com>,
        Mike Travis <travis@sgi.com>, Dimitri Sivanich <sivanich@sgi.com>,
        Juergen Gross <jgross@suse.com>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>
From: Dave Hansen <dave.hansen@intel.com>
Message-ID: <cc8596e6-8c6c-eb0c-4d59-ee3b97fe881f@intel.com>
Date: Wed, 14 Jun 2017 15:33:36 -0700
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On 06/13/2017 09:56 PM, Andy Lutomirski wrote:
> -	if (cpumask_test_cpu(cpu, &batch->cpumask))
> +	if (cpumask_test_cpu(cpu, &batch->cpumask)) {
> +		local_irq_disable();
>  		flush_tlb_func_local(&info, TLB_LOCAL_SHOOTDOWN);
> +		local_irq_enable();
> +	}
> +

Could you talk a little about why this needs to be local_irq_disable()
and not preempt_disable()?  Is it about the case where somebody is
trying to call flush_tlb_func_*() from an interrupt handler?