[PATCH v2 2/3] mm: Move buddy list manipulations into helpers

From: Dan Williams
Date: Wed Oct 03 2018 - 22:29:08 EST

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In preparation for runtime randomization of the zone lists, take all
(well, most of) the list_*() functions in the buddy allocator and put
them in helper functions. Provide a common control point for injecting
additional behavior when freeing pages.

Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
include/linux/mm.h | 3 --
include/linux/mm_types.h | 3 ++
include/linux/mmzone.h | 51 ++++++++++++++++++++++++++++++++++
mm/compaction.c | 4 +--
mm/page_alloc.c | 70 ++++++++++++++++++----------------------------
5 files changed, 84 insertions(+), 47 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index ca1581814fe2..1d19ec6a2b81 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -473,9 +473,6 @@ static inline void vma_set_anonymous(struct vm_area_struct *vma)
struct mmu_gather;
struct inode;

-#define page_private(page) ((page)->private)
-#define set_page_private(page, v) ((page)->private = (v))
-
#if !defined(__HAVE_ARCH_PTE_DEVMAP) || !defined(CONFIG_TRANSPARENT_HUGEPAGE)
static inline int pmd_devmap(pmd_t pmd)
{
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index cd2bc939efd0..191610be62bd 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -209,6 +209,9 @@ struct page {
#define PAGE_FRAG_CACHE_MAX_SIZE __ALIGN_MASK(32768, ~PAGE_MASK)
#define PAGE_FRAG_CACHE_MAX_ORDER get_order(PAGE_FRAG_CACHE_MAX_SIZE)

+#define page_private(page) ((page)->private)
+#define set_page_private(page, v) ((page)->private = (v))
+
struct page_frag_cache {
void * va;
#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 8f8fc7dab5cb..adf9b3a7440d 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -18,6 +18,8 @@
#include <linux/pageblock-flags.h>
#include <linux/page-flags-layout.h>
#include <linux/atomic.h>
+#include <linux/mm_types.h>
+#include <linux/page-flags.h>
#include <asm/page.h>

/* Free memory management - zoned buddy allocator. */
@@ -98,6 +100,55 @@ struct free_area {
unsigned long nr_free;
};

+/* Used for pages not on another list */
+static inline void add_to_free_area(struct page *page, struct free_area *area,
+ int migratetype)
+{
+ list_add(&page->lru, &area->free_list[migratetype]);
+ area->nr_free++;
+}
+
+/* Used for pages not on another list */
+static inline void add_to_free_area_tail(struct page *page, struct free_area *area,
+ int migratetype)
+{
+ list_add_tail(&page->lru, &area->free_list[migratetype]);
+ area->nr_free++;
+}
+
+/* Used for pages which are on another list */
+static inline void move_to_free_area(struct page *page, struct free_area *area,
+ int migratetype)
+{
+ list_move(&page->lru, &area->free_list[migratetype]);
+}
+
+static inline struct page *get_page_from_free_area(struct free_area *area,
+ int migratetype)
+{
+ return list_first_entry_or_null(&area->free_list[migratetype],
+ struct page, lru);
+}
+
+static inline void rmv_page_order(struct page *page)
+{
+ __ClearPageBuddy(page);
+ set_page_private(page, 0);
+}
+
+static inline void del_page_from_free_area(struct page *page,
+ struct free_area *area, int migratetype)
+{
+ list_del(&page->lru);
+ rmv_page_order(page);
+ area->nr_free--;
+}
+
+static inline bool free_area_empty(struct free_area *area, int migratetype)
+{
+ return list_empty(&area->free_list[migratetype]);
+}
+
struct pglist_data;

/*
diff --git a/mm/compaction.c b/mm/compaction.c
index faca45ebe62d..48736044f682 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1358,13 +1358,13 @@ static enum compact_result __compact_finished(struct zone *zone,
bool can_steal;

/* Job done if page is free of the right migratetype */
- if (!list_empty(&area->free_list[migratetype]))
+ if (!free_area_empty(area, migratetype))
return COMPACT_SUCCESS;

#ifdef CONFIG_CMA
/* MIGRATE_MOVABLE can fallback on MIGRATE_CMA */
if (migratetype == MIGRATE_MOVABLE &&
- !list_empty(&area->free_list[MIGRATE_CMA]))
+ !free_area_empty(area, MIGRATE_CMA))
return COMPACT_SUCCESS;
#endif
/*
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 9a1d97655c19..b4a1598fcab5 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -705,12 +705,6 @@ static inline void set_page_order(struct page *page, unsigned int order)
__SetPageBuddy(page);
}

-static inline void rmv_page_order(struct page *page)
-{
- __ClearPageBuddy(page);
- set_page_private(page, 0);
-}
-
/*
* This function checks whether a page is free && is the buddy
* we can coalesce a page and its buddy if
@@ -811,13 +805,11 @@ static inline void __free_one_page(struct page *page,
* Our buddy is free or it is CONFIG_DEBUG_PAGEALLOC guard page,
* merge with it and move up one order.
*/
- if (page_is_guard(buddy)) {
+ if (page_is_guard(buddy))
clear_page_guard(zone, buddy, order, migratetype);
- } else {
- list_del(&buddy->lru);
- zone->free_area[order].nr_free--;
- rmv_page_order(buddy);
- }
+ else
+ del_page_from_free_area(buddy, &zone->free_area[order],
+ migratetype);
combined_pfn = buddy_pfn & pfn;
page = page + (combined_pfn - pfn);
pfn = combined_pfn;
@@ -867,15 +859,13 @@ static inline void __free_one_page(struct page *page,
higher_buddy = higher_page + (buddy_pfn - combined_pfn);
if (pfn_valid_within(buddy_pfn) &&
page_is_buddy(higher_page, higher_buddy, order + 1)) {
- list_add_tail(&page->lru,
- &zone->free_area[order].free_list[migratetype]);
- goto out;
+ add_to_free_area_tail(page, &zone->free_area[order],
+ migratetype);
+ return;
}
}

- list_add(&page->lru, &zone->free_area[order].free_list[migratetype]);
-out:
- zone->free_area[order].nr_free++;
+ add_to_free_area(page, &zone->free_area[order], migratetype);
}

/*
@@ -1977,7 +1967,7 @@ static inline void expand(struct zone *zone, struct page *page,
if (set_page_guard(zone, &page[size], high, migratetype))
continue;

- list_add(&page[size].lru, &area->free_list[migratetype]);
+ add_to_free_area(&page[size], area, migratetype);
area->nr_free++;
set_page_order(&page[size], high);
}
@@ -2119,13 +2109,10 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
/* Find a page of the appropriate size in the preferred list */
for (current_order = order; current_order < MAX_ORDER; ++current_order) {
area = &(zone->free_area[current_order]);
- page = list_first_entry_or_null(&area->free_list[migratetype],
- struct page, lru);
+ page = get_page_from_free_area(area, migratetype);
if (!page)
continue;
- list_del(&page->lru);
- rmv_page_order(page);
- area->nr_free--;
+ del_page_from_free_area(page, area, migratetype);
expand(zone, page, order, current_order, area, migratetype);
set_pcppage_migratetype(page, migratetype);
return page;
@@ -2215,8 +2202,7 @@ static int move_freepages(struct zone *zone,
}

order = page_order(page);
- list_move(&page->lru,
- &zone->free_area[order].free_list[migratetype]);
+ move_to_free_area(page, &zone->free_area[order], migratetype);
page += 1 << order;
pages_moved += 1 << order;
}
@@ -2365,7 +2351,7 @@ static void steal_suitable_fallback(struct zone *zone, struct page *page,

single_page:
area = &zone->free_area[current_order];
- list_move(&page->lru, &area->free_list[start_type]);
+ move_to_free_area(page, area, start_type);
}

/*
@@ -2389,7 +2375,7 @@ int find_suitable_fallback(struct free_area *area, unsigned int order,
if (fallback_mt == MIGRATE_TYPES)
break;

- if (list_empty(&area->free_list[fallback_mt]))
+ if (free_area_empty(area, fallback_mt))
continue;

if (can_steal_fallback(order, migratetype))
@@ -2476,9 +2462,7 @@ static bool unreserve_highatomic_pageblock(const struct alloc_context *ac,
for (order = 0; order < MAX_ORDER; order++) {
struct free_area *area = &(zone->free_area[order]);

- page = list_first_entry_or_null(
- &area->free_list[MIGRATE_HIGHATOMIC],
- struct page, lru);
+ page = get_page_from_free_area(area, MIGRATE_HIGHATOMIC);
if (!page)
continue;

@@ -2591,8 +2575,7 @@ __rmqueue_fallback(struct zone *zone, int order, int start_migratetype)
VM_BUG_ON(current_order == MAX_ORDER);

do_steal:
- page = list_first_entry(&area->free_list[fallback_mt],
- struct page, lru);
+ page = get_page_from_free_area(area, fallback_mt);

steal_suitable_fallback(zone, page, start_migratetype, can_steal);

@@ -3019,6 +3002,7 @@ EXPORT_SYMBOL_GPL(split_page);

int __isolate_free_page(struct page *page, unsigned int order)
{
+ struct free_area *area = &page_zone(page)->free_area[order];
unsigned long watermark;
struct zone *zone;
int mt;
@@ -3043,9 +3027,8 @@ int __isolate_free_page(struct page *page, unsigned int order)
}

/* Remove page from free list */
- list_del(&page->lru);
- zone->free_area[order].nr_free--;
- rmv_page_order(page);
+
+ del_page_from_free_area(page, area, mt);

/*
* Set the pageblock if the isolated page is at least half of a
@@ -3339,13 +3322,13 @@ bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
continue;

for (mt = 0; mt < MIGRATE_PCPTYPES; mt++) {
- if (!list_empty(&area->free_list[mt]))
+ if (!free_area_empty(area, mt))
return true;
}

#ifdef CONFIG_CMA
if ((alloc_flags & ALLOC_CMA) &&
- !list_empty(&area->free_list[MIGRATE_CMA])) {
+ !free_area_empty(area, MIGRATE_CMA)) {
return true;
}
#endif
@@ -5191,7 +5174,7 @@ void show_free_areas(unsigned int filter, nodemask_t *nodemask)

types[order] = 0;
for (type = 0; type < MIGRATE_TYPES; type++) {
- if (!list_empty(&area->free_list[type]))
+ if (!free_area_empty(area, type))
types[order] |= 1 << type;
}
}
@@ -8220,6 +8203,9 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
spin_lock_irqsave(&zone->lock, flags);
pfn = start_pfn;
while (pfn < end_pfn) {
+ struct free_area *area;
+ int mt;
+
if (!pfn_valid(pfn)) {
pfn++;
continue;
@@ -8238,13 +8224,13 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
BUG_ON(page_count(page));
BUG_ON(!PageBuddy(page));
order = page_order(page);
+ area = &zone->free_area[order];
#ifdef CONFIG_DEBUG_VM
pr_info("remove from free list %lx %d %lx\n",
pfn, 1 << order, end_pfn);
#endif
- list_del(&page->lru);
- rmv_page_order(page);
- zone->free_area[order].nr_free--;
+ mt = get_pageblock_migratetype(page);
+ del_page_from_free_area(page, area, mt);
for (i = 0; i < (1 << order); i++)
SetPageReserved((page+i));
pfn += (1 << order);

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Next in thread: Dan Williams: "[PATCH v2 3/3] mm: Maintain randomization of page free lists"
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