linux-kernel - Re: in_irq_or_nmi() and RFC patch

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Message-ID: <20170330064958.uxih6ik5fkwvjqf6@hirez.programming.kicks-ass.net>
Date:   Thu, 30 Mar 2017 08:49:58 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Jesper Dangaard Brouer <brouer@...hat.com>
Cc:     Matthew Wilcox <willy@...radead.org>,
        Pankaj Gupta <pagupta@...hat.com>,
        Tariq Toukan <ttoukan.linux@...il.com>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Tariq Toukan <tariqt@...lanox.com>, netdev@...r.kernel.org,
        akpm@...ux-foundation.org, linux-mm <linux-mm@...ck.org>,
        Saeed Mahameed <saeedm@...lanox.com>,
        linux-kernel@...r.kernel.org
Subject: Re: in_irq_or_nmi() and RFC patch

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;
>  	}