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Date: Thu, 30 Mar 2017 08:49:58 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>,
        Pankaj Gupta <pagupta@redhat.com>,
        Tariq Toukan <ttoukan.linux@gmail.com>,
        Mel Gorman <mgorman@techsingularity.net>,
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        akpm@linux-foundation.org, linux-mm <linux-mm@kvack.org>,
        Saeed Mahameed <saeedm@mellanox.com>, linux-kernel@vger.kernel.org
Subject: Re: in_irq_or_nmi() and RFC patch
Message-ID: <20170330064958.uxih6ik5fkwvjqf6@hirez.programming.kicks-ass.net>
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On Wed, Mar 29, 2017 at 09:44:41PM +0200, Jesper Dangaard Brouer wrote:
> @@ -2481,7 +2481,11 @@ void free_hot_cold_page(struct page *page, bool cold)
>  	unsigned long pfn = page_to_pfn(page);
>  	int migratetype;
>  
> -	if (in_interrupt()) {
> +	/*
> +	 * Exclude (hard) IRQ and NMI context from using the pcplists.
> +	 * But allow softirq context, via disabling BH.
> +	 */
> +	if (in_irq() || irqs_disabled()) {

Why do you need irqs_disabled() ? Also, your comment is stale, it still
refers to NMI context.

>  		__free_pages_ok(page, 0);
>  		return;
>  	}