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mm: convert zone->managed_pages to atomic variable

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totalram_pages, zone->managed_pages and totalhigh_pages updates are
protected by managed_page_count_lock, but readers never care about it.
Convert these variables to atomic to avoid readers potentially seeing a
store tear.

This patch converts zone->managed_pages.  Subsequent patches will convert
totalram_panges, totalhigh_pages and eventually managed_page_count_lock
will be removed.

Main motivation was that managed_page_count_lock handling was complicating
things.  It was discussed in length here,
https://lore.kernel.org/patchwork/patch/995739/#1181785 So it seemes
better to remove the lock and convert variables to atomic, with preventing
poteintial store-to-read tearing as a bonus.

Link: http://lkml.kernel.org/r/1542090790-21750-3-git-send-email-arunks@codeaurora.org
Signed-off-by: Arun KS <arunks@codeaurora.org>
Suggested-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Arun KS 2018-12-28 00:34:24 -08:00 committed by Linus Torvalds
parent 3d6357de8a
commit 9705bea5f8
6 changed files with 34 additions and 29 deletions
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2
drivers/gpu/drm/amd/amdkfd/kfd_crat.c
View file

@ -853,7 +853,7 @@ static int kfd_fill_mem_info_for_cpu(int numa_node_id, int *avail_size,
*/
pgdat = NODE_DATA(numa_node_id);
for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++)
mem_in_bytes += pgdat->node_zones[zone_type].managed_pages;
mem_in_bytes += zone_managed_pages(&pgdat->node_zones[zone_type]);
mem_in_bytes <<= PAGE_SHIFT;
sub_type_hdr->length_low = lower_32_bits(mem_in_bytes);

9
include/linux/mmzone.h
View file

@ -435,7 +435,7 @@ struct zone {
* adjust_managed_page_count() should be used instead of directly
* touching zone->managed_pages and totalram_pages.
*/
unsigned long managed_pages;
atomic_long_t managed_pages;
unsigned long spanned_pages;
unsigned long present_pages;
@ -524,6 +524,11 @@ enum pgdat_flags {
PGDAT_RECLAIM_LOCKED, /* prevents concurrent reclaim */
};
static inline unsigned long zone_managed_pages(struct zone *zone)
{
return (unsigned long)atomic_long_read(&zone->managed_pages);
}
static inline unsigned long zone_end_pfn(const struct zone *zone)
{
return zone->zone_start_pfn + zone->spanned_pages;
@ -820,7 +825,7 @@ static inline bool is_dev_zone(const struct zone *zone)
*/
static inline bool managed_zone(struct zone *zone)
{
return zone->managed_pages;
return zone_managed_pages(zone);
}
/* Returns true if a zone has memory */

2
lib/show_mem.c
View file

@ -28,7 +28,7 @@ void show_mem(unsigned int filter, nodemask_t *nodemask)
continue;
total += zone->present_pages;
reserved += zone->present_pages - zone->managed_pages;
reserved += zone->present_pages - zone_managed_pages(zone);
if (is_highmem_idx(zoneid))
highmem += zone->present_pages;

2
mm/memblock.c
View file

@ -1950,7 +1950,7 @@ void reset_node_managed_pages(pg_data_t *pgdat)
struct zone *z;
for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++)
z->managed_pages = 0;
atomic_long_set(&z->managed_pages, 0);
}
void __init reset_all_zones_managed_pages(void)

44
mm/page_alloc.c
View file

@ -1280,7 +1280,7 @@ static void __init __free_pages_boot_core(struct page *page, unsigned int order)
__ClearPageReserved(p);
set_page_count(p, 0);
page_zone(page)->managed_pages += nr_pages;
atomic_long_add(nr_pages, &page_zone(page)->managed_pages);
set_page_refcounted(page);
__free_pages(page, order);
}
@ -2259,7 +2259,7 @@ static void reserve_highatomic_pageblock(struct page *page, struct zone *zone,
* Limit the number reserved to 1 pageblock or roughly 1% of a zone.
* Check is race-prone but harmless.
*/
max_managed = (zone->managed_pages / 100) + pageblock_nr_pages;
max_managed = (zone_managed_pages(zone) / 100) + pageblock_nr_pages;
if (zone->nr_reserved_highatomic >= max_managed)
return;
@ -4661,7 +4661,7 @@ static unsigned long nr_free_zone_pages(int offset)
struct zonelist *zonelist = node_zonelist(numa_node_id(), GFP_KERNEL);
for_each_zone_zonelist(zone, z, zonelist, offset) {
unsigned long size = zone->managed_pages;
unsigned long size = zone_managed_pages(zone);
unsigned long high = high_wmark_pages(zone);
if (size > high)
sum += size - high;
@ -4768,7 +4768,7 @@ void si_meminfo_node(struct sysinfo *val, int nid)
pg_data_t *pgdat = NODE_DATA(nid);
for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++)
managed_pages += pgdat->node_zones[zone_type].managed_pages;
managed_pages += zone_managed_pages(&pgdat->node_zones[zone_type]);
val->totalram = managed_pages;
val->sharedram = node_page_state(pgdat, NR_SHMEM);
val->freeram = sum_zone_node_page_state(nid, NR_FREE_PAGES);
@ -4777,7 +4777,7 @@ void si_meminfo_node(struct sysinfo *val, int nid)
struct zone *zone = &pgdat->node_zones[zone_type];
if (is_highmem(zone)) {
managed_highpages += zone->managed_pages;
managed_highpages += zone_managed_pages(zone);
free_highpages += zone_page_state(zone, NR_FREE_PAGES);
}
}
@ -4984,7 +4984,7 @@ void show_free_areas(unsigned int filter, nodemask_t *nodemask)
K(zone_page_state(zone, NR_ZONE_UNEVICTABLE)),
K(zone_page_state(zone, NR_ZONE_WRITE_PENDING)),
K(zone->present_pages),
K(zone->managed_pages),
K(zone_managed_pages(zone)),
K(zone_page_state(zone, NR_MLOCK)),
zone_page_state(zone, NR_KERNEL_STACK_KB),
K(zone_page_state(zone, NR_PAGETABLE)),
@ -5656,7 +5656,7 @@ static int zone_batchsize(struct zone *zone)
* The per-cpu-pages pools are set to around 1000th of the
* size of the zone.
*/
batch = zone->managed_pages / 1024;
batch = zone_managed_pages(zone) / 1024;
/* But no more than a meg. */
if (batch * PAGE_SIZE > 1024 * 1024)
batch = (1024 * 1024) / PAGE_SIZE;
@ -5766,7 +5766,7 @@ static void pageset_set_high_and_batch(struct zone *zone,
{
if (percpu_pagelist_fraction)
pageset_set_high(pcp,
(zone->managed_pages /
(zone_managed_pages(zone) /
percpu_pagelist_fraction));
else
pageset_set_batch(pcp, zone_batchsize(zone));
@ -6323,7 +6323,7 @@ static void __meminit pgdat_init_internals(struct pglist_data *pgdat)
static void __meminit zone_init_internals(struct zone *zone, enum zone_type idx, int nid,
unsigned long remaining_pages)
{
zone->managed_pages = remaining_pages;
atomic_long_set(&zone->managed_pages, remaining_pages);
zone_set_nid(zone, nid);
zone->name = zone_names[idx];
zone->zone_pgdat = NODE_DATA(nid);
@ -7076,7 +7076,7 @@ early_param("movablecore", cmdline_parse_movablecore);
void adjust_managed_page_count(struct page *page, long count)
{
spin_lock(&managed_page_count_lock);
page_zone(page)->managed_pages += count;
atomic_long_add(count, &page_zone(page)->managed_pages);
totalram_pages += count;
#ifdef CONFIG_HIGHMEM
if (PageHighMem(page))
@ -7124,7 +7124,7 @@ void free_highmem_page(struct page *page)
{
__free_reserved_page(page);
totalram_pages++;
page_zone(page)->managed_pages++;
atomic_long_inc(&page_zone(page)->managed_pages);
totalhigh_pages++;
}
#endif
@ -7257,7 +7257,7 @@ static void calculate_totalreserve_pages(void)
for (i = 0; i < MAX_NR_ZONES; i++) {
struct zone *zone = pgdat->node_zones + i;
long max = 0;
unsigned long managed_pages = zone->managed_pages;
unsigned long managed_pages = zone_managed_pages(zone);
/* Find valid and maximum lowmem_reserve in the zone */
for (j = i; j < MAX_NR_ZONES; j++) {
@ -7293,7 +7293,7 @@ static void setup_per_zone_lowmem_reserve(void)
for_each_online_pgdat(pgdat) {
for (j = 0; j < MAX_NR_ZONES; j++) {
struct zone *zone = pgdat->node_zones + j;
unsigned long managed_pages = zone->managed_pages;
unsigned long managed_pages = zone_managed_pages(zone);
zone->lowmem_reserve[j] = 0;
@ -7311,7 +7311,7 @@ static void setup_per_zone_lowmem_reserve(void)
lower_zone->lowmem_reserve[j] =
managed_pages / sysctl_lowmem_reserve_ratio[idx];
}
managed_pages += lower_zone->managed_pages;
managed_pages += zone_managed_pages(lower_zone);
}
}
}
@ -7330,14 +7330,14 @@ static void __setup_per_zone_wmarks(void)
/* Calculate total number of !ZONE_HIGHMEM pages */
for_each_zone(zone) {
if (!is_highmem(zone))
lowmem_pages += zone->managed_pages;
lowmem_pages += zone_managed_pages(zone);
}
for_each_zone(zone) {
u64 tmp;
spin_lock_irqsave(&zone->lock, flags);
tmp = (u64)pages_min * zone->managed_pages;
tmp = (u64)pages_min * zone_managed_pages(zone);
do_div(tmp, lowmem_pages);
if (is_highmem(zone)) {
/*
@ -7351,7 +7351,7 @@ static void __setup_per_zone_wmarks(void)
*/
unsigned long min_pages;
min_pages = zone->managed_pages / 1024;
min_pages = zone_managed_pages(zone) / 1024;
min_pages = clamp(min_pages, SWAP_CLUSTER_MAX, 128UL);
zone->watermark[WMARK_MIN] = min_pages;
} else {
@ -7368,7 +7368,7 @@ static void __setup_per_zone_wmarks(void)
* ensure a minimum size on small systems.
*/
tmp = max_t(u64, tmp >> 2,
mult_frac(zone->managed_pages,
mult_frac(zone_managed_pages(zone),
watermark_scale_factor, 10000));
zone->watermark[WMARK_LOW] = min_wmark_pages(zone) + tmp;
@ -7498,8 +7498,8 @@ static void setup_min_unmapped_ratio(void)
pgdat->min_unmapped_pages = 0;
for_each_zone(zone)
zone->zone_pgdat->min_unmapped_pages += (zone->managed_pages *
sysctl_min_unmapped_ratio) / 100;
zone->zone_pgdat->min_unmapped_pages += (zone_managed_pages(zone) *
sysctl_min_unmapped_ratio) / 100;
}
@ -7526,8 +7526,8 @@ static void setup_min_slab_ratio(void)
pgdat->min_slab_pages = 0;
for_each_zone(zone)
zone->zone_pgdat->min_slab_pages += (zone->managed_pages *
sysctl_min_slab_ratio) / 100;
zone->zone_pgdat->min_slab_pages += (zone_managed_pages(zone) *
sysctl_min_slab_ratio) / 100;
}
int sysctl_min_slab_ratio_sysctl_handler(struct ctl_table *table, int write,

4
mm/vmstat.c
View file

@ -227,7 +227,7 @@ int calculate_normal_threshold(struct zone *zone)
* 125 1024 10 16-32 GB 9
*/
mem = zone->managed_pages >> (27 - PAGE_SHIFT);
mem = zone_managed_pages(zone) >> (27 - PAGE_SHIFT);
threshold = 2 * fls(num_online_cpus()) * (1 + fls(mem));
@ -1569,7 +1569,7 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
high_wmark_pages(zone),
zone->spanned_pages,
zone->present_pages,
zone->managed_pages);
zone_managed_pages(zone));
seq_printf(m,
"\n protection: (%ld",