[PATCH 1/7] mm/page_alloc: Add page->buddy_list and page->pcp_list

Mel Gorman
2022-06-13T17:36:21Z

The page allocator uses page->lru for storing pages on either buddy or PCP
lists. Create page->buddy_list and page->pcp_list as a union with
page->lru. This is simply to clarify what type of list a page is on in
the page allocator.

No functional change intended.

[minchan@kernel.org: fix page lru fields in macros]
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Tested-by: Minchan Kim <minchan@kernel.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
---
include/linux/mm_types.h | 5 +++++
mm/page_alloc.c | 24 ++++++++++++------------
2 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index b34ff2cdbc4f..c09b7f0555b8 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -87,6 +87,7 @@ struct page {
*/
union {
struct list_head lru;
+
/* Or, for the Unevictable "LRU list" slot */
struct {
/* Always even, to negate PageTail */
@@ -94,6 +95,10 @@ struct page {
/* Count page's or folio's mlocks */
unsigned int mlock_count;
};
+
+ /* Or, free page */
+ struct list_head buddy_list;
+ struct list_head pcp_list;
};
/* See page-flags.h for PAGE_MAPPING_FLAGS */
struct address_space *mapping;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e008a3df0485..247fa7502199 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -785,7 +785,7 @@ static inline bool set_page_guard(struct zone *zone, struct page *page,
return false;

__SetPageGuard(page);
- INIT_LIST_HEAD(&page->lru);
+ INIT_LIST_HEAD(&page->buddy_list);
set_page_private(page, order);
/* Guard pages are not available for any usage */
__mod_zone_freepage_state(zone, -(1 << order), migratetype);
@@ -928,7 +928,7 @@ static inline void add_to_free_list(struct page *page, struct zone *zone,
{
struct free_area *area = &zone->free_area[order];

- list_add(&page->lru, &area->free_list[migratetype]);
+ list_add(&page->buddy_list, &area->free_list[migratetype]);
area->nr_free++;
}

@@ -938,7 +938,7 @@ static inline void add_to_free_list_tail(struct page *page, struct zone *zone,
{
struct free_area *area = &zone->free_area[order];

- list_add_tail(&page->lru, &area->free_list[migratetype]);
+ list_add_tail(&page->buddy_list, &area->free_list[migratetype]);
area->nr_free++;
}

@@ -952,7 +952,7 @@ static inline void move_to_free_list(struct page *page, struct zone *zone,
{
struct free_area *area = &zone->free_area[order];

- list_move_tail(&page->lru, &area->free_list[migratetype]);
+ list_move_tail(&page->buddy_list, &area->free_list[migratetype]);
}

static inline void del_page_from_free_list(struct page *page, struct zone *zone,
@@ -962,7 +962,7 @@ static inline void del_page_from_free_list(struct page *page, struct zone *zone,
if (page_reported(page))
__ClearPageReported(page);

- list_del(&page->lru);
+ list_del(&page->buddy_list);
__ClearPageBuddy(page);
set_page_private(page, 0);
zone->free_area[order].nr_free--;
@@ -1504,11 +1504,11 @@ static void free_pcppages_bulk(struct zone *zone, int count,
do {
int mt;

- page = list_last_entry(list, struct page, lru);
+ page = list_last_entry(list, struct page, pcp_list);
mt = get_pcppage_migratetype(page);

/* must delete to avoid corrupting pcp list */
- list_del(&page->lru);
+ list_del(&page->pcp_list);
count -= nr_pages;
pcp->count -= nr_pages;

@@ -3068,7 +3068,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
* for IO devices that can merge IO requests if the physical
* pages are ordered properly.
*/
- list_add_tail(&page->lru, list);
+ list_add_tail(&page->pcp_list, list);
allocated++;
if (is_migrate_cma(get_pcppage_migratetype(page)))
__mod_zone_page_state(zone, NR_FREE_CMA_PAGES,
@@ -3318,7 +3318,7 @@ void mark_free_pages(struct zone *zone)

for_each_migratetype_order(order, t) {
list_for_each_entry(page,
- &zone->free_area[order].free_list[t], lru) {
+ &zone->free_area[order].free_list[t], buddy_list) {
unsigned long i;

pfn = page_to_pfn(page);
@@ -3407,7 +3407,7 @@ static void free_unref_page_commit(struct page *page, int migratetype,
__count_vm_event(PGFREE);
pcp = this_cpu_ptr(zone->per_cpu_pageset);
pindex = order_to_pindex(migratetype, order);
- list_add(&page->lru, &pcp->lists[pindex]);
+ list_add(&page->pcp_list, &pcp->lists[pindex]);
pcp->count += 1 << order;

/*
@@ -3670,8 +3670,8 @@ struct page *__rmqueue_pcplist(struct zone *zone, unsigned int order,
return NULL;
}

- page = list_first_entry(list, struct page, lru);
- list_del(&page->lru);
+ page = list_first_entry(list, struct page, pcp_list);
+ list_del(&page->pcp_list);
pcp->count -= 1 << order;
} while (check_new_pcp(page, order));

--
2.35.3