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mm/page_alloc: Introduce free_area_init_core_hotplug
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Currently, whenever a new node is created/re-used from the memhotplug
path, we call free_area_init_node()->free_area_init_core().  But there is
some code that we do not really need to run when we are coming from such
path.

free_area_init_core() performs the following actions:

1) Initializes pgdat internals, such as spinlock, waitqueues and more.
2) Account # nr_all_pages and # nr_kernel_pages. These values are used later on
   when creating hash tables.
3) Account number of managed_pages per zone, substracting dma_reserved and
   memmap pages.
4) Initializes some fields of the zone structure data
5) Calls init_currently_empty_zone to initialize all the freelists
6) Calls memmap_init to initialize all pages belonging to certain zone

When called from memhotplug path, free_area_init_core() only performs
actions #1 and #4.

Action #2 is pointless as the zones do not have any pages since either the
node was freed, or we are re-using it, eitherway all zones belonging to
this node should have 0 pages.  For the same reason, action #3 results
always in manages_pages being 0.

Action #5 and torvalds#6 are performed later on when onlining the pages:
 online_pages()->move_pfn_range_to_zone()->init_currently_empty_zone()
 online_pages()->move_pfn_range_to_zone()->memmap_init_zone()

This patch does two things:

First, moves the node/zone initializtion to their own function, so it
allows us to create a small version of free_area_init_core, where we only
perform:

1) Initialization of pgdat internals, such as spinlock, waitqueues and more
4) Initialization of some fields of the zone structure data

These two functions are: pgdat_init_internals() and zone_init_internals().

The second thing this patch does, is to introduce
free_area_init_core_hotplug(), the memhotplug version of
free_area_init_core():

Currently, we call free_area_init_node() from the memhotplug path.  In
there, we set some pgdat's fields, and call calculate_node_totalpages().
calculate_node_totalpages() calculates the # of pages the node has.

Since the node is either new, or we are re-using it, the zones belonging
to this node should not have any pages, so there is no point to calculate
this now.

Actually, we re-set these values to 0 later on with the calls to:

reset_node_managed_pages()
reset_node_present_pages()

The # of pages per node and the # of pages per zone will be calculated when
onlining the pages:

online_pages()->move_pfn_range()->move_pfn_range_to_zone()->resize_zone_range()
online_pages()->move_pfn_range()->move_pfn_range_to_zone()->resize_pgdat_range()

Also, since free_area_init_core/free_area_init_node will now only get called during early init, let us replace
__paginginit with __init, so their code gets freed up.

Link: http://lkml.kernel.org/r/20180730101757.28058-5-osalvador@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
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@osalvadorvilardaga @sfrothwell
osalvadorvilardaga authored and sfrothwell committed Aug 12, 2018
1 parent 23cf25e commit 5a43dc1
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Showing 3 changed files with 60 additions and 33 deletions.
6 changes: 5 additions & 1 deletion include/linux/mm.h
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Original file line number Diff line number Diff line change
Expand Up @@ -2015,10 +2015,14 @@ static inline spinlock_t *pud_lock(struct mm_struct *mm, pud_t *pud)

extern void __init pagecache_init(void);
extern void free_area_init(unsigned long * zones_size);
extern void free_area_init_node(int nid, unsigned long * zones_size,
extern void __init free_area_init_node(int nid, unsigned long * zones_size,
unsigned long zone_start_pfn, unsigned long *zholes_size);
extern void free_initmem(void);

#ifdef CONFIG_MEMORY_HOTPLUG
extern void __ref free_area_init_core_hotplug(int nid);
#endif

/*
* Free reserved pages within range [PAGE_ALIGN(start), end & PAGE_MASK)
* into the buddy system. The freed pages will be poisoned with pattern
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16 changes: 5 additions & 11 deletions mm/memory_hotplug.c
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Original file line number Diff line number Diff line change
Expand Up @@ -982,8 +982,6 @@ static void reset_node_present_pages(pg_data_t *pgdat)
static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
{
struct pglist_data *pgdat;
unsigned long zones_size[MAX_NR_ZONES] = {0};
unsigned long zholes_size[MAX_NR_ZONES] = {0};
unsigned long start_pfn = PFN_DOWN(start);

pgdat = NODE_DATA(nid);
Expand All @@ -1006,8 +1004,11 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)

/* we can use NODE_DATA(nid) from here */

pgdat->node_id = nid;
pgdat->node_start_pfn = start_pfn;

/* init node's zones as empty zones, we don't have any present pages.*/
free_area_init_node(nid, zones_size, start_pfn, zholes_size);
free_area_init_core_hotplug(nid);
pgdat->per_cpu_nodestats = alloc_percpu(struct per_cpu_nodestat);

/*
Expand All @@ -1016,19 +1017,12 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
*/
build_all_zonelists(pgdat);

/*
* zone->managed_pages is set to an approximate value in
* free_area_init_core(), which will cause
* /sys/device/system/node/nodeX/meminfo has wrong data.
* So reset it to 0 before any memory is onlined.
*/
reset_node_managed_pages(pgdat);

/*
* When memory is hot-added, all the memory is in offline state. So
* clear all zones' present_pages because they will be updated in
* online_pages() and offline_pages().
*/
reset_node_managed_pages(pgdat);
reset_node_present_pages(pgdat);

return pgdat;
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71 changes: 50 additions & 21 deletions mm/page_alloc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6227,21 +6227,9 @@ static void pgdat_init_kcompactd(struct pglist_data *pgdat)
static void pgdat_init_kcompactd(struct pglist_data *pgdat) {}
#endif

/*
* Set up the zone data structures:
* - mark all pages reserved
* - mark all memory queues empty
* - clear the memory bitmaps
*
* NOTE: pgdat should get zeroed by caller.
*/
static void __meminit free_area_init_core(struct pglist_data *pgdat)
static void __meminit pgdat_init_internals(struct pglist_data *pgdat)
{
enum zone_type j;
int nid = pgdat->node_id;

pgdat_resize_init(pgdat);

pgdat_init_numabalancing(pgdat);
pgdat_init_split_queue(pgdat);
pgdat_init_kcompactd(pgdat);
Expand All @@ -6252,7 +6240,54 @@ static void __meminit free_area_init_core(struct pglist_data *pgdat)
pgdat_page_ext_init(pgdat);
spin_lock_init(&pgdat->lru_lock);
lruvec_init(node_lruvec(pgdat));
}

static void __paginginit zone_init_internals(struct zone *zone, enum zone_type idx, int nid,
unsigned long remaining_pages)
{
zone->managed_pages = remaining_pages;
zone_set_nid(zone, nid);
zone->name = zone_names[idx];
zone->zone_pgdat = NODE_DATA(nid);
spin_lock_init(&zone->lock);
zone_seqlock_init(zone);
zone_pcp_init(zone);
}

/*
* Set up the zone data structures
* - init pgdat internals
* - init all zones belonging to this node
*
* NOTE: this function is only called during memory hotplug
*/
#ifdef CONFIG_MEMORY_HOTPLUG
void __ref free_area_init_core_hotplug(int nid)
{
enum zone_type z;
pg_data_t *pgdat = NODE_DATA(nid);

pgdat_init_internals(pgdat);
for (z = 0; z < MAX_NR_ZONES; z++)
zone_init_internals(&pgdat->node_zones[z], z, nid, 0);
}
#endif

/*
* Set up the zone data structures:
* - mark all pages reserved
* - mark all memory queues empty
* - clear the memory bitmaps
*
* NOTE: pgdat should get zeroed by caller.
* NOTE: this function is only called during early init.
*/
static void __init free_area_init_core(struct pglist_data *pgdat)
{
enum zone_type j;
int nid = pgdat->node_id;

pgdat_init_internals(pgdat);
pgdat->per_cpu_nodestats = &boot_nodestats;

for (j = 0; j < MAX_NR_ZONES; j++) {
Expand Down Expand Up @@ -6300,13 +6335,7 @@ static void __meminit free_area_init_core(struct pglist_data *pgdat)
* when the bootmem allocator frees pages into the buddy system.
* And all highmem pages will be managed by the buddy system.
*/
zone->managed_pages = freesize;
zone_set_nid(zone, nid);
zone->name = zone_names[j];
zone->zone_pgdat = pgdat;
spin_lock_init(&zone->lock);
zone_seqlock_init(zone);
zone_pcp_init(zone);
zone_init_internals(zone, j, nid, freesize);

if (!size)
continue;
Expand Down Expand Up @@ -6381,7 +6410,7 @@ static inline void pgdat_set_deferred_range(pg_data_t *pgdat)
static inline void pgdat_set_deferred_range(pg_data_t *pgdat) {}
#endif

void __meminit free_area_init_node(int nid, unsigned long *zones_size,
void __init free_area_init_node(int nid, unsigned long *zones_size,
unsigned long node_start_pfn,
unsigned long *zholes_size)
{
Expand Down

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