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@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Gioh Kim <gioh.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index df542feaac3bb6ce749c408cca37623af9ad19bf..2e8b7f39605aaceec01e9fad922de7243d81269b 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -439,18 +439,29 @@ 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)
@@ -581,12 +592,7 @@ 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--;
@@ -861,23 +867,17 @@ 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);