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Commit 2847cf95 authored by Joonsoo Kim's avatar Joonsoo Kim Committed by Linus Torvalds
Browse files

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: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Gioh Kim <gioh.kim@lge.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4308ce17

mm/page_alloc.c

+19 −19
Original line number Diff line number Diff line
@@ -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);