Free page accounting currently happens a bit too high up the call
stack, where it has to deal with guard pages, compaction capturing,
block stealing and even page isolation. This is subtle and fragile,
and makes it difficult to hack on the code.
Push the accounting down to where pages enter and leave the physical
freelists, where all these higher-level exceptions are of no concern.
v2:
- fix CONFIG_DEBUG_PAGEALLOC build (Mel)
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
---
include/linux/mm.h | 18 ++---
include/linux/page-isolation.h | 3 +-
include/linux/vmstat.h | 8 --
mm/debug_page_alloc.c | 12 +--
mm/internal.h | 5 --
mm/page_alloc.c | 131 ++++++++++++++++++---------------
mm/page_isolation.c | 7 +-
7 files changed, 88 insertions(+), 96 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 406ab9ea818f..950c400ac53b 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3550,24 +3550,22 @@ static inline bool page_is_guard(struct page *page)
return PageGuard(page);
}
-bool __set_page_guard(struct zone *zone, struct page *page, unsigned int order,
- int migratetype);
+bool __set_page_guard(struct zone *zone, struct page *page, unsigned int order);
static inline bool set_page_guard(struct zone *zone, struct page *page,
- unsigned int order, int migratetype)
+ unsigned int order)
{
if (!debug_guardpage_enabled())
return false;
- return __set_page_guard(zone, page, order, migratetype);
+ return __set_page_guard(zone, page, order);
}
-void __clear_page_guard(struct zone *zone, struct page *page, unsigned int order,
- int migratetype);
+void __clear_page_guard(struct zone *zone, struct page *page, unsigned int order);
static inline void clear_page_guard(struct zone *zone, struct page *page,
- unsigned int order, int migratetype)
+ unsigned int order)
{
if (!debug_guardpage_enabled())
return;
- __clear_page_guard(zone, page, order, migratetype);
+ __clear_page_guard(zone, page, order);
}
#else /* CONFIG_DEBUG_PAGEALLOC */
@@ -3577,9 +3575,9 @@ static inline unsigned int debug_guardpage_minorder(void) { return 0; }
static inline bool debug_guardpage_enabled(void) { return false; }
static inline bool page_is_guard(struct page *page) { return false; }
static inline bool set_page_guard(struct zone *zone, struct page *page,
- unsigned int order, int migratetype) { return false; }
+ unsigned int order) { return false; }
static inline void clear_page_guard(struct zone *zone, struct page *page,
- unsigned int order, int migratetype) {}
+ unsigned int order) {}
#endif /* CONFIG_DEBUG_PAGEALLOC */
#ifdef __HAVE_ARCH_GATE_AREA
diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h
index 8550b3c91480..901915747960 100644
--- a/include/linux/page-isolation.h
+++ b/include/linux/page-isolation.h
@@ -34,7 +34,8 @@ static inline bool is_migrate_isolate(int migratetype)
#define REPORT_FAILURE 0x2
void set_pageblock_migratetype(struct page *page, int migratetype);
-int move_freepages_block(struct zone *zone, struct page *page, int migratetype);
+int move_freepages_block(struct zone *zone, struct page *page,
+ int old_mt, int new_mt);
int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
int migratetype, int flags, gfp_t gfp_flags);
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index fed855bae6d8..a4eae03f6094 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -487,14 +487,6 @@ static inline void node_stat_sub_folio(struct folio *folio,
mod_node_page_state(folio_pgdat(folio), item, -folio_nr_pages(folio));
}
-static inline void __mod_zone_freepage_state(struct zone *zone, int nr_pages,
- int migratetype)
-{
- __mod_zone_page_state(zone, NR_FREE_PAGES, nr_pages);
- if (is_migrate_cma(migratetype))
- __mod_zone_page_state(zone, NR_FREE_CMA_PAGES, nr_pages);
-}
-
extern const char * const vmstat_text[];
static inline const char *zone_stat_name(enum zone_stat_item item)
diff --git a/mm/debug_page_alloc.c b/mm/debug_page_alloc.c
index f9d145730fd1..03a810927d0a 100644
--- a/mm/debug_page_alloc.c
+++ b/mm/debug_page_alloc.c
@@ -32,8 +32,7 @@ static int __init debug_guardpage_minorder_setup(char *buf)
}
early_param("debug_guardpage_minorder", debug_guardpage_minorder_setup);
-bool __set_page_guard(struct zone *zone, struct page *page, unsigned int order,
- int migratetype)
+bool __set_page_guard(struct zone *zone, struct page *page, unsigned int order)
{
if (order >= debug_guardpage_minorder())
return false;
@@ -41,19 +40,12 @@ bool __set_page_guard(struct zone *zone, struct page *page, unsigned int order,
__SetPageGuard(page);
INIT_LIST_HEAD(&page->buddy_list);
set_page_private(page, order);
- /* Guard pages are not available for any usage */
- if (!is_migrate_isolate(migratetype))
- __mod_zone_freepage_state(zone, -(1 << order), migratetype);
return true;
}
-void __clear_page_guard(struct zone *zone, struct page *page, unsigned int order,
- int migratetype)
+void __clear_page_guard(struct zone *zone, struct page *page, unsigned int order)
{
__ClearPageGuard(page);
-
set_page_private(page, 0);
- if (!is_migrate_isolate(migratetype))
- __mod_zone_freepage_state(zone, (1 << order), migratetype);
}
diff --git a/mm/internal.h b/mm/internal.h
index a7d9e980429a..d86fd621880e 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -865,11 +865,6 @@ static inline bool is_migrate_highatomic(enum migratetype migratetype)
return migratetype == MIGRATE_HIGHATOMIC;
}
-static inline bool is_migrate_highatomic_page(struct page *page)
-{
- return get_pageblock_migratetype(page) == MIGRATE_HIGHATOMIC;
-}
-
void setup_zone_pageset(struct zone *zone);
struct migration_target_control {
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 42b62832323f..e7e790a64237 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -676,24 +676,36 @@ compaction_capture(struct capture_control *capc, struct page *page,
}
#endif /* CONFIG_COMPACTION */
-/* Used for pages not on another list */
-static inline void add_to_free_list(struct page *page, struct zone *zone,
- unsigned int order, int migratetype)
+static inline void account_freepages(struct page *page, struct zone *zone,
+ int nr_pages, int migratetype)
{
- struct free_area *area = &zone->free_area[order];
+ if (is_migrate_isolate(migratetype))
+ return;
- list_add(&page->buddy_list, &area->free_list[migratetype]);
- area->nr_free++;
+ __mod_zone_page_state(zone, NR_FREE_PAGES, nr_pages);
+
+ if (is_migrate_cma(migratetype))
+ __mod_zone_page_state(zone, NR_FREE_CMA_PAGES, nr_pages);
}
/* Used for pages not on another list */
-static inline void add_to_free_list_tail(struct page *page, struct zone *zone,
- unsigned int order, int migratetype)
+static inline void add_to_free_list(struct page *page, struct zone *zone,
+ unsigned int order, int migratetype,
+ bool tail)
{
struct free_area *area = &zone->free_area[order];
- list_add_tail(&page->buddy_list, &area->free_list[migratetype]);
+ VM_WARN_ONCE(get_pageblock_migratetype(page) != migratetype,
+ "page type is %lu, passed migratetype is %d (nr=%d)\n",
+ get_pageblock_migratetype(page), migratetype, 1 << order);
+
+ if (tail)
+ list_add_tail(&page->buddy_list, &area->free_list[migratetype]);
+ else
+ list_add(&page->buddy_list, &area->free_list[migratetype]);
area->nr_free++;
+
+ account_freepages(page, zone, 1 << order, migratetype);
}
/*
@@ -702,16 +714,28 @@ static inline void add_to_free_list_tail(struct page *page, struct zone *zone,
* allocation again (e.g., optimization for memory onlining).
*/
static inline void move_to_free_list(struct page *page, struct zone *zone,
- unsigned int order, int migratetype)
+ unsigned int order, int old_mt, int new_mt)
{
struct free_area *area = &zone->free_area[order];
- list_move_tail(&page->buddy_list, &area->free_list[migratetype]);
+ /* Free page moving can fail, so it happens before the type update */
+ VM_WARN_ONCE(get_pageblock_migratetype(page) != old_mt,
+ "page type is %lu, passed migratetype is %d (nr=%d)\n",
+ get_pageblock_migratetype(page), old_mt, 1 << order);
+
+ list_move_tail(&page->buddy_list, &area->free_list[new_mt]);
+
+ account_freepages(page, zone, -(1 << order), old_mt);
+ account_freepages(page, zone, 1 << order, new_mt);
}
static inline void del_page_from_free_list(struct page *page, struct zone *zone,
- unsigned int order)
+ unsigned int order, int migratetype)
{
+ VM_WARN_ONCE(get_pageblock_migratetype(page) != migratetype,
+ "page type is %lu, passed migratetype is %d (nr=%d)\n",
+ get_pageblock_migratetype(page), migratetype, 1 << order);
+
/* clear reported state and update reported page count */
if (page_reported(page))
__ClearPageReported(page);
@@ -720,6 +744,8 @@ static inline void del_page_from_free_list(struct page *page, struct zone *zone,
__ClearPageBuddy(page);
set_page_private(page, 0);
zone->free_area[order].nr_free--;
+
+ account_freepages(page, zone, -(1 << order), migratetype);
}
static inline struct page *get_page_from_free_area(struct free_area *area,
@@ -793,23 +819,21 @@ static inline void __free_one_page(struct page *page,
VM_BUG_ON_PAGE(page->flags & PAGE_FLAGS_CHECK_AT_PREP, page);
VM_BUG_ON(migratetype == -1);
- if (likely(!is_migrate_isolate(migratetype)))
- __mod_zone_freepage_state(zone, 1 << order, migratetype);
-
VM_BUG_ON_PAGE(pfn & ((1 << order) - 1), page);
VM_BUG_ON_PAGE(bad_range(zone, page), page);
while (order < MAX_ORDER) {
- if (compaction_capture(capc, page, order, migratetype)) {
- __mod_zone_freepage_state(zone, -(1 << order),
- migratetype);
+ int buddy_mt;
+
+ if (compaction_capture(capc, page, order, migratetype))
return;
- }
buddy = find_buddy_page_pfn(page, pfn, order, &buddy_pfn);
if (!buddy)
goto done_merging;
+ buddy_mt = get_pfnblock_migratetype(buddy, buddy_pfn);
+
if (unlikely(order >= pageblock_order)) {
/*
* We want to prevent merge between freepages on pageblock
@@ -837,9 +861,9 @@ 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(zone, buddy, order, migratetype);
+ clear_page_guard(zone, buddy, order);
else
- del_page_from_free_list(buddy, zone, order);
+ del_page_from_free_list(buddy, zone, order, buddy_mt);
combined_pfn = buddy_pfn & pfn;
page = page + (combined_pfn - pfn);
pfn = combined_pfn;
@@ -856,10 +880,7 @@ static inline void __free_one_page(struct page *page,
else
to_tail = buddy_merge_likely(pfn, buddy_pfn, page, order);
- if (to_tail)
- add_to_free_list_tail(page, zone, order, migratetype);
- else
- add_to_free_list(page, zone, order, migratetype);
+ add_to_free_list(page, zone, order, migratetype, to_tail);
/* Notify page reporting subsystem of freed page */
if (!(fpi_flags & FPI_SKIP_REPORT_NOTIFY))
@@ -901,10 +922,8 @@ int split_free_page(struct page *free_page,
}
mt = get_pfnblock_migratetype(free_page, free_page_pfn);
- if (likely(!is_migrate_isolate(mt)))
- __mod_zone_freepage_state(zone, -(1UL << order), mt);
+ del_page_from_free_list(free_page, zone, order, mt);
- del_page_from_free_list(free_page, zone, order);
for (pfn = free_page_pfn;
pfn < free_page_pfn + (1UL << order);) {
int mt = get_pfnblock_migratetype(pfn_to_page(pfn), pfn);
@@ -1433,10 +1452,10 @@ static inline void expand(struct zone *zone, struct page *page,
* Corresponding page table entries will not be touched,
* pages will stay not present in virtual address space
*/
- if (set_page_guard(zone, &page[size], high, migratetype))
+ if (set_page_guard(zone, &page[size], high))
continue;
- add_to_free_list(&page[size], zone, high, migratetype);
+ add_to_free_list(&page[size], zone, high, migratetype, false);
set_buddy_order(&page[size], high);
}
}
@@ -1606,7 +1625,7 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
page = get_page_from_free_area(area, migratetype);
if (!page)
continue;
- del_page_from_free_list(page, zone, current_order);
+ del_page_from_free_list(page, zone, current_order, migratetype);
expand(zone, page, order, current_order, migratetype);
trace_mm_page_alloc_zone_locked(page, order, migratetype,
pcp_allowed_order(order) &&
@@ -1647,7 +1666,7 @@ static inline struct page *__rmqueue_cma_fallback(struct zone *zone,
* boundary. If alignment is required, use move_freepages_block()
*/
static int move_freepages(struct zone *zone, unsigned long start_pfn,
- unsigned long end_pfn, int migratetype)
+ unsigned long end_pfn, int old_mt, int new_mt)
{
struct page *page;
unsigned long pfn;
@@ -1666,7 +1685,7 @@ static int move_freepages(struct zone *zone, unsigned long start_pfn,
VM_BUG_ON_PAGE(page_zone(page) != zone, page);
order = buddy_order(page);
- move_to_free_list(page, zone, order, migratetype);
+ move_to_free_list(page, zone, order, old_mt, new_mt);
pfn += 1 << order;
pages_moved += 1 << order;
}
@@ -1721,7 +1740,7 @@ static bool prep_move_freepages_block(struct zone *zone, struct page *page,
}
int move_freepages_block(struct zone *zone, struct page *page,
- int migratetype)
+ int old_mt, int new_mt)
{
unsigned long start_pfn, end_pfn;
@@ -1729,7 +1748,7 @@ int move_freepages_block(struct zone *zone, struct page *page,
NULL, NULL))
return -1;
- return move_freepages(zone, start_pfn, end_pfn, migratetype);
+ return move_freepages(zone, start_pfn, end_pfn, old_mt, new_mt);
}
/*
@@ -1829,7 +1848,7 @@ static void steal_suitable_fallback(struct zone *zone, struct page *page,
/* Take ownership for orders >= pageblock_order */
if (current_order >= pageblock_order) {
- del_page_from_free_list(page, zone, current_order);
+ del_page_from_free_list(page, zone, current_order, block_type);
change_pageblock_range(page, current_order, start_type);
expand(zone, page, order, current_order, start_type);
return;
@@ -1880,13 +1899,13 @@ static void steal_suitable_fallback(struct zone *zone, struct page *page,
*/
if (free_pages + alike_pages >= (1 << (pageblock_order-1)) ||
page_group_by_mobility_disabled) {
- move_freepages(zone, start_pfn, end_pfn, start_type);
+ move_freepages(zone, start_pfn, end_pfn, block_type, start_type);
set_pageblock_migratetype(page, start_type);
block_type = start_type;
}
single_page:
- del_page_from_free_list(page, zone, current_order);
+ del_page_from_free_list(page, zone, current_order, block_type);
expand(zone, page, order, current_order, block_type);
}
@@ -1952,7 +1971,8 @@ static void reserve_highatomic_pageblock(struct page *page, struct zone *zone,
mt = get_pageblock_migratetype(page);
/* Only reserve normal pageblocks (i.e., they can merge with others) */
if (migratetype_is_mergeable(mt)) {
- if (move_freepages_block(zone, page, MIGRATE_HIGHATOMIC) != -1) {
+ if (move_freepages_block(zone, page,
+ mt, MIGRATE_HIGHATOMIC) != -1) {
set_pageblock_migratetype(page, MIGRATE_HIGHATOMIC);
zone->nr_reserved_highatomic += pageblock_nr_pages;
}
@@ -1995,11 +2015,13 @@ static bool unreserve_highatomic_pageblock(const struct alloc_context *ac,
spin_lock_irqsave(&zone->lock, flags);
for (order = 0; order <= MAX_ORDER; order++) {
struct free_area *area = &(zone->free_area[order]);
+ int mt;
page = get_page_from_free_area(area, MIGRATE_HIGHATOMIC);
if (!page)
continue;
+ mt = get_pageblock_migratetype(page);
/*
* In page freeing path, migratetype change is racy so
* we can counter several free pages in a pageblock
@@ -2007,7 +2029,7 @@ static bool unreserve_highatomic_pageblock(const struct alloc_context *ac,
* from highatomic to ac->migratetype. So we should
* adjust the count once.
*/
- if (is_migrate_highatomic_page(page)) {
+ if (is_migrate_highatomic(mt)) {
/*
* It should never happen but changes to
* locking could inadvertently allow a per-cpu
@@ -2029,7 +2051,8 @@ static bool unreserve_highatomic_pageblock(const struct alloc_context *ac,
* of pageblocks that cannot be completely freed
* may increase.
*/
- ret = move_freepages_block(zone, page, ac->migratetype);
+ ret = move_freepages_block(zone, page, mt,
+ ac->migratetype);
/*
* Reserving this block already succeeded, so this should
* not fail on zone boundaries.
@@ -2202,12 +2225,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
* pages are ordered properly.
*/
list_add_tail(&page->pcp_list, list);
- if (is_migrate_cma(get_pageblock_migratetype(page)))
- __mod_zone_page_state(zone, NR_FREE_CMA_PAGES,
- -(1 << order));
}
-
- __mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order));
spin_unlock_irqrestore(&zone->lock, flags);
return i;
@@ -2604,11 +2622,9 @@ int __isolate_free_page(struct page *page, unsigned int order)
watermark = zone->_watermark[WMARK_MIN] + (1UL << order);
if (!zone_watermark_ok(zone, 0, watermark, 0, ALLOC_CMA))
return 0;
-
- __mod_zone_freepage_state(zone, -(1UL << order), mt);
}
- del_page_from_free_list(page, zone, order);
+ del_page_from_free_list(page, zone, order, mt);
/*
* Set the pageblock if the isolated page is at least half of a
@@ -2623,7 +2639,7 @@ int __isolate_free_page(struct page *page, unsigned int order)
* with others)
*/
if (migratetype_is_mergeable(mt) &&
- move_freepages_block(zone, page,
+ move_freepages_block(zone, page, mt,
MIGRATE_MOVABLE) != -1)
set_pageblock_migratetype(page, MIGRATE_MOVABLE);
}
@@ -2715,8 +2731,6 @@ struct page *rmqueue_buddy(struct zone *preferred_zone, struct zone *zone,
return NULL;
}
}
- __mod_zone_freepage_state(zone, -(1 << order),
- get_pageblock_migratetype(page));
spin_unlock_irqrestore(&zone->lock, flags);
} while (check_new_pages(page, order));
@@ -6488,8 +6502,9 @@ void __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
BUG_ON(page_count(page));
BUG_ON(!PageBuddy(page));
+ VM_WARN_ON(get_pageblock_migratetype(page) != MIGRATE_ISOLATE);
order = buddy_order(page);
- del_page_from_free_list(page, zone, order);
+ del_page_from_free_list(page, zone, order, MIGRATE_ISOLATE);
pfn += (1 << order);
}
spin_unlock_irqrestore(&zone->lock, flags);
@@ -6540,11 +6555,12 @@ static void break_down_buddy_pages(struct zone *zone, struct page *page,
current_buddy = page + size;
}
- if (set_page_guard(zone, current_buddy, high, migratetype))
+ if (set_page_guard(zone, current_buddy, high))
continue;
if (current_buddy != target) {
- add_to_free_list(current_buddy, zone, high, migratetype);
+ add_to_free_list(current_buddy, zone, high,
+ migratetype, false);
set_buddy_order(current_buddy, high);
page = next_page;
}
@@ -6572,12 +6588,11 @@ bool take_page_off_buddy(struct page *page)
int migratetype = get_pfnblock_migratetype(page_head,
pfn_head);
- del_page_from_free_list(page_head, zone, page_order);
+ del_page_from_free_list(page_head, zone, page_order,
+ migratetype);
break_down_buddy_pages(zone, page_head, page, 0,
page_order, migratetype);
SetPageHWPoisonTakenOff(page);
- if (!is_migrate_isolate(migratetype))
- __mod_zone_freepage_state(zone, -1, migratetype);
ret = true;
break;
}
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index f5e4d8676b36..b0705e709973 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -181,13 +181,12 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_
int nr_pages;
int mt = get_pageblock_migratetype(page);
- nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE);
+ nr_pages = move_freepages_block(zone, page, mt, MIGRATE_ISOLATE);
/* Block spans zone boundaries? */
if (nr_pages == -1) {
spin_unlock_irqrestore(&zone->lock, flags);
return -EBUSY;
}
- __mod_zone_freepage_state(zone, -nr_pages, mt);
set_pageblock_migratetype(page, MIGRATE_ISOLATE);
zone->nr_isolate_pageblock++;
spin_unlock_irqrestore(&zone->lock, flags);
@@ -255,13 +254,13 @@ static void unset_migratetype_isolate(struct page *page, int migratetype)
* allocation.
*/
if (!isolated_page) {
- int nr_pages = move_freepages_block(zone, page, migratetype);
+ int nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE,
+ migratetype);
/*
* Isolating this block already succeeded, so this
* should not fail on zone boundaries.
*/
WARN_ON_ONCE(nr_pages == -1);
- __mod_zone_freepage_state(zone, nr_pages, migratetype);
}
set_pageblock_migratetype(page, migratetype);
if (isolated_page)
--
2.41.0
