linux-kernel - [PATCH v2 4/6] mm/page_isolation: cleanup set_migratetype

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Date:   Thu, 30 Jul 2020 11:34:14 +0200
From:   David Hildenbrand <david@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     virtualization@...ts.linux-foundation.org, linux-mm@...ck.org,
        David Hildenbrand <david@...hat.com>,
        Baoquan He <bhe@...hat.com>,
        Pankaj Gupta <pankaj.gupta.linux@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        "Michael S . Tsirkin" <mst@...hat.com>,
        Mike Kravetz <mike.kravetz@...cle.com>
Subject: [PATCH v2 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.

Reviewed-by: Baoquan He <bhe@...hat.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Michael S. Tsirkin <mst@...hat.com>
Cc: Mike Kravetz <mike.kravetz@...cle.com>
Signed-off-by: David Hildenbrand <david@...hat.com>
---
 mm/page_isolation.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index d099aac479601..e65fe5d770849 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);
 
@@ -51,13 +48,13 @@ 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;
 	}
 
 	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.
@@ -65,7 +62,7 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_
 		dump_page(unmovable, "unmovable page");
 	}
 
-	return ret;
+	return -EBUSY;
 }
 
 static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
-- 
2.26.2