2014-11-07 오후 4:35에 Joonsoo Kim 이(가) 쓴 글:
> 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....@lge.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);
>
Looks good!
Thanks for your work.
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