linux-kernel - [PATCH 2/2] mm/debug-pagealloc: cleanup page guard code

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Date:	Fri,  7 Nov 2014 16:35:46 +0900
From:	Joonsoo Kim <iamjoonsoo.kim@....com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Rik van Riel <riel@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Mel Gorman <mgorman@...e.de>,
	Johannes Weiner <hannes@...xchg.org>,
	Minchan Kim <minchan@...nel.org>,
	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
	Zhang Yanfei <zhangyanfei@...fujitsu.com>,
	Tang Chen <tangchen@...fujitsu.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Wen Congyang <wency@...fujitsu.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Michal Nazarewicz <mina86@...a86.com>,
	Laura Abbott <lauraa@...eaurora.org>,
	Heesub Shin <heesub.shin@...sung.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	Ritesh Harjani <ritesh.list@...il.com>,
	t.stanislaws@...sung.com, Gioh Kim <gioh.kim@....com>,
	Vlastimil Babka <vbabka@...e.cz>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: [PATCH 2/2] mm/debug-pagealloc: cleanup page guard code

Page guard is used by debug-pagealloc feature. Currently,
it is open-coded, but, I think that more abstraction of it makes
core page allocator code more readable.

There is no functional difference.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>
---
 mm/page_alloc.c |   38 +++++++++++++++++++-------------------
 1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d673f64..c0dbede 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -440,18 +440,29 @@ static int __init debug_guardpage_minorder_setup(char *buf)
 }
 __setup("debug_guardpage_minorder=", debug_guardpage_minorder_setup);
 
-static inline void set_page_guard_flag(struct page *page)
+static inline void set_page_guard(struct zone *zone, struct page *page,
+				unsigned int order, int migratetype)
 {
 	__set_bit(PAGE_DEBUG_FLAG_GUARD, &page->debug_flags);
+	INIT_LIST_HEAD(&page->lru);
+	set_page_private(page, order);
+	/* Guard pages are not available for any usage */
+	__mod_zone_freepage_state(zone, -(1 << order), migratetype);
 }
 
-static inline void clear_page_guard_flag(struct page *page)
+static inline void clear_page_guard(struct zone *zone, struct page *page,
+				unsigned int order, int migratetype)
 {
 	__clear_bit(PAGE_DEBUG_FLAG_GUARD, &page->debug_flags);
+	set_page_private(page, 0);
+	if (!is_migrate_isolate(migratetype))
+		__mod_zone_freepage_state(zone, (1 << order), migratetype);
 }
 #else
-static inline void set_page_guard_flag(struct page *page) { }
-static inline void clear_page_guard_flag(struct page *page) { }
+static inline void set_page_guard(struct zone *zone, struct page *page,
+				unsigned int order, int migratetype) {}
+static inline void clear_page_guard(struct zone *zone, struct page *page,
+				unsigned int order, int migratetype) {}
 #endif
 
 static inline void set_page_order(struct page *page, unsigned int order)
@@ -582,12 +593,7 @@ static inline void __free_one_page(struct page *page,
 		 * merge with it and move up one order.
 		 */
 		if (page_is_guard(buddy)) {
-			clear_page_guard_flag(buddy);
-			set_page_private(buddy, 0);
-			if (!is_migrate_isolate(migratetype)) {
-				__mod_zone_freepage_state(zone, 1 << order,
-							  migratetype);
-			}
+			clear_page_guard(zone, buddy, order, migratetype);
 		} else {
 			list_del(&buddy->lru);
 			zone->free_area[order].nr_free--;
@@ -862,23 +868,17 @@ static inline void expand(struct zone *zone, struct page *page,
 		size >>= 1;
 		VM_BUG_ON_PAGE(bad_range(zone, &page[size]), &page[size]);
 
-#ifdef CONFIG_DEBUG_PAGEALLOC
-		if (high < debug_guardpage_minorder()) {
+		if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC) &&
+			high < debug_guardpage_minorder()) {
 			/*
 			 * Mark as guard pages (or page), that will allow to
 			 * merge back to allocator when buddy will be freed.
 			 * Corresponding page table entries will not be touched,
 			 * pages will stay not present in virtual address space
 			 */
-			INIT_LIST_HEAD(&page[size].lru);
-			set_page_guard_flag(&page[size]);
-			set_page_private(&page[size], high);
-			/* Guard pages are not available for any usage */
-			__mod_zone_freepage_state(zone, -(1 << high),
-						  migratetype);
+			set_page_guard(zone, &page[size], high, migratetype);
 			continue;
 		}
-#endif
 		list_add(&page[size].lru, &area->free_list[migratetype]);
 		area->nr_free++;
 		set_page_order(&page[size], high);
-- 
1.7.9.5

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