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Subject[PATCH] mm: use managed_zone() for more exact check in zone iteration
Date
For one zone, there are three digits to describe its space range:

spanned_pages
present_pages
managed_pages

The detailed meaning is written in include/linux/mmzone.h. This patch
concerns about the last two.

present_pages is physical pages existing within the zone
managed_pages is present pages managed by the buddy system

From the definition, managed_pages is a more strict condition than
present_pages.

There are two functions using zone's present_pages as a boundary:

populated_zone()
for_each_populated_zone()

By going through the kernel tree, most of their users are willing to
access pages managed by the buddy system, which means it is more exact
to check zone's managed_pages for a validation.

This patch replaces those checks on present_pages to managed_pages by:

* change for_each_populated_zone() to for_each_managed_zone()
* convert for_each_populated_zone() to for_each_zone() and check
populated_zone() where is necessary
* change populated_zone() to managed_zone() at proper places

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>

---

Michal, after last mail, I did one more thing to replace
populated_zone() with managed_zone() at proper places.

One thing I am not sure is those places in mm/compaction.c. I have
chaged them. If not, please let me know.

BTW, I did a boot up test with the patched kernel and looks smooth.
---
arch/s390/mm/page-states.c | 2 +-
include/linux/mmzone.h | 8 +++-----
kernel/power/snapshot.c | 31 ++++++++++++++++++++-----------
mm/compaction.c | 8 ++++----
mm/highmem.c | 5 ++---
mm/huge_memory.c | 2 +-
mm/khugepaged.c | 2 +-
mm/madvise.c | 2 +-
mm/migrate.c | 2 +-
mm/page-writeback.c | 4 ++--
mm/page_alloc.c | 19 +++++++++----------
mm/vmstat.c | 14 +++++++-------
12 files changed, 52 insertions(+), 47 deletions(-)

diff --git a/arch/s390/mm/page-states.c b/arch/s390/mm/page-states.c
index dc3cede7f2ec..015430bf0c63 100644
--- a/arch/s390/mm/page-states.c
+++ b/arch/s390/mm/page-states.c
@@ -265,7 +265,7 @@ void arch_set_page_states(int make_stable)
return;
if (make_stable)
drain_local_pages(NULL);
- for_each_populated_zone(zone) {
+ for_each_managed_zone(zone) {
spin_lock_irqsave(&zone->lock, flags);
for_each_migratetype_order(order, t) {
list_for_each(l, &zone->free_area[order].free_list[t]) {
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 847705a6d0ec..2174baba0546 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -937,11 +937,9 @@ extern struct zone *next_zone(struct zone *zone);
zone; \
zone = next_zone(zone))

-#define for_each_populated_zone(zone) \
- for (zone = (first_online_pgdat())->node_zones; \
- zone; \
- zone = next_zone(zone)) \
- if (!populated_zone(zone)) \
+#define for_each_managed_zone(zone) \
+ for_each_zone(zone) \
+ if (!managed_zone(zone)) \
; /* do nothing */ \
else

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index b0308a2c6000..aa99efa73d89 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -592,10 +592,13 @@ static int create_mem_extents(struct list_head *list, gfp_t gfp_mask)

INIT_LIST_HEAD(list);

- for_each_populated_zone(zone) {
+ for_each_zone(zone) {
unsigned long zone_start, zone_end;
struct mem_extent *ext, *cur, *aux;

+ if (!populated_zone(zone))
+ continue;
+
zone_start = zone->zone_start_pfn;
zone_end = zone_end_pfn(zone);

@@ -1193,8 +1196,8 @@ static unsigned int count_free_highmem_pages(void)
struct zone *zone;
unsigned int cnt = 0;

- for_each_populated_zone(zone)
- if (is_highmem(zone))
+ for_each_zone(zone)
+ if (populated_zone(zone) && is_highmem(zone))
cnt += zone_page_state(zone, NR_FREE_PAGES);

return cnt;
@@ -1239,10 +1242,10 @@ static unsigned int count_highmem_pages(void)
struct zone *zone;
unsigned int n = 0;

- for_each_populated_zone(zone) {
+ for_each_zone(zone) {
unsigned long pfn, max_zone_pfn;

- if (!is_highmem(zone))
+ if (!populated_zone(zone) || !is_highmem(zone))
continue;

mark_free_pages(zone);
@@ -1305,8 +1308,8 @@ static unsigned int count_data_pages(void)
unsigned long pfn, max_zone_pfn;
unsigned int n = 0;

- for_each_populated_zone(zone) {
- if (is_highmem(zone))
+ for_each_zone(zone) {
+ if (!populated_zone(zone) || is_highmem(zone))
continue;

mark_free_pages(zone);
@@ -1399,9 +1402,12 @@ static void copy_data_pages(struct memory_bitmap *copy_bm,
struct zone *zone;
unsigned long pfn;

- for_each_populated_zone(zone) {
+ for_each_zone(zone) {
unsigned long max_zone_pfn;

+ if (!populated_zone(zone))
+ continue;
+
mark_free_pages(zone);
max_zone_pfn = zone_end_pfn(zone);
for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
@@ -1717,7 +1723,10 @@ int hibernate_preallocate_memory(void)
saveable += save_highmem;
highmem = save_highmem;
size = 0;
- for_each_populated_zone(zone) {
+ for_each_zone(zone) {
+ if (!populated_zone(zone))
+ continue;
+
size += snapshot_additional_pages(zone);
if (is_highmem(zone))
highmem += zone_page_state(zone, NR_FREE_PAGES);
@@ -1863,8 +1872,8 @@ static int enough_free_mem(unsigned int nr_pages, unsigned int nr_highmem)
struct zone *zone;
unsigned int free = alloc_normal;

- for_each_populated_zone(zone)
- if (!is_highmem(zone))
+ for_each_zone(zone)
+ if (populated_zone(zone) && !is_highmem(zone))
free += zone_page_state(zone, NR_FREE_PAGES);

nr_pages += count_pages_for_highmem(nr_highmem);
diff --git a/mm/compaction.c b/mm/compaction.c
index 7c607479de4a..8867c011dd45 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -276,7 +276,7 @@ void reset_isolation_suitable(pg_data_t *pgdat)

for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
struct zone *zone = &pgdat->node_zones[zoneid];
- if (!populated_zone(zone))
+ if (!managed_zone(zone))
continue;

/* Only flush if a full compaction finished recently */
@@ -1832,7 +1832,7 @@ static void compact_node(int nid)
for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {

zone = &pgdat->node_zones[zoneid];
- if (!populated_zone(zone))
+ if (!managed_zone(zone))
continue;

cc.nr_freepages = 0;
@@ -1927,7 +1927,7 @@ static bool kcompactd_node_suitable(pg_data_t *pgdat)
for (zoneid = 0; zoneid <= classzone_idx; zoneid++) {
zone = &pgdat->node_zones[zoneid];

- if (!populated_zone(zone))
+ if (!managed_zone(zone))
continue;

if (compaction_suitable(zone, pgdat->kcompactd_max_order, 0,
@@ -1963,7 +1963,7 @@ static void kcompactd_do_work(pg_data_t *pgdat)
int status;

zone = &pgdat->node_zones[zoneid];
- if (!populated_zone(zone))
+ if (!managed_zone(zone))
continue;

if (compaction_deferred(zone, cc.order))
diff --git a/mm/highmem.c b/mm/highmem.c
index 59db3223a5d6..1edc0539d25a 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -111,15 +111,14 @@ EXPORT_SYMBOL(totalhigh_pages);

EXPORT_PER_CPU_SYMBOL(__kmap_atomic_idx);

-unsigned int nr_free_highpages (void)
+unsigned int nr_free_highpages(void)
{
struct zone *zone;
unsigned int pages = 0;

- for_each_populated_zone(zone) {
+ for_each_managed_zone(zone)
if (is_highmem(zone))
pages += zone_page_state(zone, NR_FREE_PAGES);
- }

return pages;
}
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 4e4ef8fa479d..d0f97b29c96f 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2829,7 +2829,7 @@ static int split_huge_pages_set(void *data, u64 val)
if (val != 1)
return -EINVAL;

- for_each_populated_zone(zone) {
+ for_each_managed_zone(zone) {
max_zone_pfn = zone_end_pfn(zone);
for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
if (!pfn_valid(pfn))
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index c13625c1ad5e..4c3ec240d4d9 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1845,7 +1845,7 @@ static void set_recommended_min_free_kbytes(void)
int nr_zones = 0;
unsigned long recommended_min;

- for_each_populated_zone(zone) {
+ for_each_managed_zone(zone) {
/*
* We don't need to worry about fragmentation of
* ZONE_MOVABLE since it only has movable pages.
diff --git a/mm/madvise.c b/mm/madvise.c
index 6cb1ca93e290..3a8eced61107 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -677,7 +677,7 @@ static int madvise_inject_error(int behavior,
}

/* Ensure that all poisoned pages are removed from per-cpu lists */
- for_each_populated_zone(zone)
+ for_each_managed_zone(zone)
drain_all_pages(zone);

return 0;
diff --git a/mm/migrate.c b/mm/migrate.c
index f7e4bfdc13b7..5c4846dd0ae3 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1819,7 +1819,7 @@ static bool migrate_balanced_pgdat(struct pglist_data *pgdat,
for (z = pgdat->nr_zones - 1; z >= 0; z--) {
struct zone *zone = pgdat->node_zones + z;

- if (!populated_zone(zone))
+ if (!managed_zone(zone))
continue;

/* Avoid waking kswapd by allocating pages_to_migrate pages. */
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 3f690bae6b78..076f51e86149 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -281,7 +281,7 @@ static unsigned long node_dirtyable_memory(struct pglist_data *pgdat)
for (z = 0; z < MAX_NR_ZONES; z++) {
struct zone *zone = pgdat->node_zones + z;

- if (!populated_zone(zone))
+ if (!managed_zone(zone))
continue;

nr_pages += zone_page_state(zone, NR_FREE_PAGES);
@@ -316,7 +316,7 @@ static unsigned long highmem_dirtyable_memory(unsigned long total)
continue;

z = &NODE_DATA(node)->node_zones[i];
- if (!populated_zone(z))
+ if (!managed_zone(z))
continue;

nr_pages = zone_page_state(z, NR_FREE_PAGES);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c20d3c76bd59..458bd81cf75c 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1747,7 +1747,7 @@ void __init page_alloc_init_late(void)
memblock_discard();
#endif

- for_each_populated_zone(zone)
+ for_each_managed_zone(zone)
set_zone_contiguous(zone);
}

@@ -2569,9 +2569,8 @@ static void drain_pages(unsigned int cpu)
{
struct zone *zone;

- for_each_populated_zone(zone) {
+ for_each_managed_zone(zone)
drain_pages_zone(cpu, zone);
- }
}

/*
@@ -2655,7 +2654,7 @@ void drain_all_pages(struct zone *zone)
if (pcp->pcp.count)
has_pcps = true;
} else {
- for_each_populated_zone(z) {
+ for_each_managed_zone(z) {
pcp = per_cpu_ptr(z->pageset, cpu);
if (pcp->pcp.count) {
has_pcps = true;
@@ -4857,7 +4856,7 @@ void show_free_areas(unsigned int filter, nodemask_t *nodemask)
struct zone *zone;
pg_data_t *pgdat;

- for_each_populated_zone(zone) {
+ for_each_managed_zone(zone) {
if (show_mem_node_skip(filter, zone_to_nid(zone), nodemask))
continue;

@@ -4940,7 +4939,7 @@ void show_free_areas(unsigned int filter, nodemask_t *nodemask)
"yes" : "no");
}

- for_each_populated_zone(zone) {
+ for_each_managed_zone(zone) {
int i;

if (show_mem_node_skip(filter, zone_to_nid(zone), nodemask))
@@ -4999,7 +4998,7 @@ void show_free_areas(unsigned int filter, nodemask_t *nodemask)
printk(KERN_CONT "\n");
}

- for_each_populated_zone(zone) {
+ for_each_managed_zone(zone) {
unsigned int order;
unsigned long nr[MAX_ORDER], flags, total = 0;
unsigned char types[MAX_ORDER];
@@ -5787,7 +5786,7 @@ void __init setup_per_cpu_pageset(void)
struct pglist_data *pgdat;
struct zone *zone;

- for_each_populated_zone(zone)
+ for_each_managed_zone(zone)
setup_zone_pageset(zone);

for_each_online_pgdat(pgdat)
@@ -6905,7 +6904,7 @@ static void check_for_memory(pg_data_t *pgdat, int nid)

for (zone_type = 0; zone_type <= ZONE_MOVABLE - 1; zone_type++) {
struct zone *zone = &pgdat->node_zones[zone_type];
- if (populated_zone(zone)) {
+ if (managed_zone(zone)) {
if (IS_ENABLED(CONFIG_HIGHMEM))
node_set_state(nid, N_HIGH_MEMORY);
if (zone_type <= ZONE_NORMAL)
@@ -7581,7 +7580,7 @@ int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *table, int write,
if (percpu_pagelist_fraction == old_percpu_pagelist_fraction)
goto out;

- for_each_populated_zone(zone) {
+ for_each_managed_zone(zone) {
unsigned int cpu;

for_each_possible_cpu(cpu)
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 6038ce593ce3..06cd9e9ecba1 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -53,7 +53,7 @@ static void zero_zones_numa_counters(void)
{
struct zone *zone;

- for_each_populated_zone(zone)
+ for_each_managed_zone(zone)
zero_zone_numa_counters(zone);
}

@@ -256,7 +256,7 @@ void refresh_zone_stat_thresholds(void)
}
}

- for_each_populated_zone(zone) {
+ for_each_managed_zone(zone) {
struct pglist_data *pgdat = zone->zone_pgdat;
unsigned long max_drift, tolerate_drift;

@@ -753,7 +753,7 @@ static int refresh_cpu_vm_stats(bool do_pagesets)
int global_node_diff[NR_VM_NODE_STAT_ITEMS] = { 0, };
int changes = 0;

- for_each_populated_zone(zone) {
+ for_each_managed_zone(zone) {
struct per_cpu_pageset __percpu *p = zone->pageset;

for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
@@ -854,7 +854,7 @@ void cpu_vm_stats_fold(int cpu)
#endif
int global_node_diff[NR_VM_NODE_STAT_ITEMS] = { 0, };

- for_each_populated_zone(zone) {
+ for_each_managed_zone(zone) {
struct per_cpu_pageset *p;

p = per_cpu_ptr(zone->pageset, cpu);
@@ -1578,8 +1578,8 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
seq_printf(m, ", %ld", zone->lowmem_reserve[i]);
seq_putc(m, ')');

- /* If unpopulated, no other information is useful */
- if (!populated_zone(zone)) {
+ /* If unmanaged, no other information is useful */
+ if (!managed_zone(zone)) {
seq_putc(m, '\n');
return;
}
@@ -1817,7 +1817,7 @@ static bool need_update(int cpu)
{
struct zone *zone;

- for_each_populated_zone(zone) {
+ for_each_managed_zone(zone) {
struct per_cpu_pageset *p = per_cpu_ptr(zone->pageset, cpu);

BUILD_BUG_ON(sizeof(p->vm_stat_diff[0]) != 1);
--
2.15.1
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