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

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Date:   Thu, 30 Jul 2020 06:31:00 +0200
From:   Pankaj Gupta <pankaj.gupta.linux@...il.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        virtualization@...ts.linux-foundation.org,
        Linux MM <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()

> 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;
>  }
>
>  static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
> --

This clean up looks good to me.

Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@...il.com>

> 2.26.2
>
>