linux-kernel - Re: [PATCH v1 4/6] mm/page_isolation: cleanup set_migratetype

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Message-ID: <20200729140631.GH14854@MiWiFi-R3L-srv>
Date:   Wed, 29 Jul 2020 22:06:31 +0800
From:   Baoquan He <bhe@...hat.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, linux-mm@...ck.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        "Michael S . Tsirkin" <mst@...hat.com>
Subject: Re: [PATCH v1 4/6] mm/page_isolation: cleanup
 set_migratetype_isolate()

On 06/30/20 at 04:26pm, David Hildenbrand wrote:
> Let's clean it up a bit, simplifying error handling and getting rid of
> the label.
> 
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Michal Hocko <mhocko@...e.com>
> Cc: Michael S. Tsirkin <mst@...hat.com>
> Signed-off-by: David Hildenbrand <david@...hat.com>
> ---
>  mm/page_isolation.c | 18 +++++++-----------
>  1 file changed, 7 insertions(+), 11 deletions(-)
> 
> diff --git a/mm/page_isolation.c b/mm/page_isolation.c
> index 02a01bff6b219..5f869bef23fa4 100644
> --- a/mm/page_isolation.c
> +++ b/mm/page_isolation.c
> @@ -17,12 +17,9 @@
>  
>  static int set_migratetype_isolate(struct page *page, int migratetype, int isol_flags)
>  {
> -	struct page *unmovable = NULL;
> -	struct zone *zone;
> +	struct zone *zone = page_zone(page);
> +	struct page *unmovable;
>  	unsigned long flags;
> -	int ret = -EBUSY;
> -
> -	zone = page_zone(page);
>  
>  	spin_lock_irqsave(&zone->lock, flags);
>  
> @@ -51,21 +48,20 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_
>  									NULL);
>  
>  		__mod_zone_freepage_state(zone, -nr_pages, mt);
> -		ret = 0;
> +		spin_unlock_irqrestore(&zone->lock, flags);
> +		drain_all_pages(zone);
> +		return 0;
>  	}
>  
> -out:
>  	spin_unlock_irqrestore(&zone->lock, flags);
> -	if (!ret) {
> -		drain_all_pages(zone);
> -	} else if ((isol_flags & REPORT_FAILURE) && unmovable)
> +	if (isol_flags & REPORT_FAILURE)
>  		/*
>  		 * printk() with zone->lock held will likely trigger a
>  		 * lockdep splat, so defer it here.
>  		 */
>  		dump_page(unmovable, "unmovable page");
>  
> -	return ret;
> +	return -EBUSY;

Reviewed-by: Baoquan He <bhe@...hat.com>