From: Oscar Salvador <osalva...@suse.de>

When free_area_init_core gets called from the memhotplug code,
we only need to perform some of the operations in
there.

Since memhotplug code is the only place where free_area_init_core
gets called while node being still offline, we can better separate
the context from where it is called.

This patch re-structures the code for that purpose.

Signed-off-by: Oscar Salvador <osalva...@suse.de>
---
 mm/page_alloc.c | 94 +++++++++++++++++++++++++++++++--------------------------
 1 file changed, 52 insertions(+), 42 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8a73305f7c55..d652a3ad720c 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6237,6 +6237,40 @@ static void pgdat_init_kcompactd(struct pglist_data 
*pgdat)
 static void pgdat_init_kcompactd(struct pglist_data *pgdat) {}
 #endif
 
+static unsigned long calc_remaining_pages(enum zone_type type, unsigned long 
freesize,
+                                                               unsigned long 
size)
+{
+       unsigned long memmap_pages = calc_memmap_size(size, freesize);
+
+       if(!is_highmem_idx(type)) {
+               if (freesize >= memmap_pages) {
+                       freesize -= memmap_pages;
+                       if (memmap_pages)
+                               printk(KERN_DEBUG
+                                       "  %s zone: %lu pages used for 
memmap\n",
+                                       zone_names[type], memmap_pages);
+               } else
+                       pr_warn("  %s zone: %lu pages exceeds freesize %lu\n",
+                               zone_names[type], memmap_pages, freesize);
+       }
+
+       /* Account for reserved pages */
+       if (type == 0 && freesize > dma_reserve) {
+               freesize -= dma_reserve;
+               printk(KERN_DEBUG "  %s zone: %lu pages reserved\n",
+               zone_names[0], dma_reserve);
+       }
+
+       if (!is_highmem_idx(type))
+               nr_kernel_pages += freesize;
+       /* Charge for highmem memmap if there are enough kernel pages */
+       else if (nr_kernel_pages > memmap_pages * 2)
+               nr_kernel_pages -= memmap_pages;
+       nr_all_pages += freesize;
+
+       return freesize;
+}
+
 /*
  * Set up the zone data structures:
  *   - mark all pages reserved
@@ -6249,6 +6283,7 @@ static void __paginginit free_area_init_core(struct 
pglist_data *pgdat)
 {
        enum zone_type j;
        int nid = pgdat->node_id;
+       bool no_hotplug_context;
 
        pgdat_resize_init(pgdat);
 
@@ -6265,45 +6300,18 @@ static void __paginginit free_area_init_core(struct 
pglist_data *pgdat)
 
        pgdat->per_cpu_nodestats = &boot_nodestats;
 
+       /* Memhotplug is the only place where free_area_init_node gets called
+        * with the node being still offline.
+        */
+       no_hotplug_context = node_online(nid);
+
        for (j = 0; j < MAX_NR_ZONES; j++) {
                struct zone *zone = pgdat->node_zones + j;
-               unsigned long size, freesize, memmap_pages;
-               unsigned long zone_start_pfn = zone->zone_start_pfn;
+               unsigned long size = zone->spanned_pages;
+               unsigned long freesize = zone->present_pages;
 
-               size = zone->spanned_pages;
-               freesize = zone->present_pages;
-
-               /*
-                * Adjust freesize so that it accounts for how much memory
-                * is used by this zone for memmap. This affects the watermark
-                * and per-cpu initialisations
-                */
-               memmap_pages = calc_memmap_size(size, freesize);
-               if (!is_highmem_idx(j)) {
-                       if (freesize >= memmap_pages) {
-                               freesize -= memmap_pages;
-                               if (memmap_pages)
-                                       printk(KERN_DEBUG
-                                              "  %s zone: %lu pages used for 
memmap\n",
-                                              zone_names[j], memmap_pages);
-                       } else
-                               pr_warn("  %s zone: %lu pages exceeds freesize 
%lu\n",
-                                       zone_names[j], memmap_pages, freesize);
-               }
-
-               /* Account for reserved pages */
-               if (j == 0 && freesize > dma_reserve) {
-                       freesize -= dma_reserve;
-                       printk(KERN_DEBUG "  %s zone: %lu pages reserved\n",
-                                       zone_names[0], dma_reserve);
-               }
-
-               if (!is_highmem_idx(j))
-                       nr_kernel_pages += freesize;
-               /* Charge for highmem memmap if there are enough kernel pages */
-               else if (nr_kernel_pages > memmap_pages * 2)
-                       nr_kernel_pages -= memmap_pages;
-               nr_all_pages += freesize;
+               if (no_hotplug_context)
+                       freesize = calc_remaining_pages(j, freesize, size);
 
                /*
                 * Set an approximate value for lowmem here, it will be adjusted
@@ -6311,6 +6319,7 @@ static void __paginginit free_area_init_core(struct 
pglist_data *pgdat)
                 * And all highmem pages will be managed by the buddy system.
                 */
                zone->managed_pages = freesize;
+
 #ifdef CONFIG_NUMA
                zone->node = nid;
 #endif
@@ -6320,13 +6329,14 @@ static void __paginginit free_area_init_core(struct 
pglist_data *pgdat)
                zone_seqlock_init(zone);
                zone_pcp_init(zone);
 
-               if (!size)
-                       continue;
+               if (size && no_hotplug_context) {
+                       unsigned long zone_start_pfn = zone->zone_start_pfn;
 
-               set_pageblock_order();
-               setup_usemap(pgdat, zone, zone_start_pfn, size);
-               init_currently_empty_zone(zone, zone_start_pfn, size);
-               memmap_init(size, nid, j, zone_start_pfn);
+                       set_pageblock_order();
+                       setup_usemap(pgdat, zone, zone_start_pfn, size);
+                       init_currently_empty_zone(zone, zone_start_pfn, size);
+                       memmap_init(size, nid, j, zone_start_pfn);
+               }
        }
 }
 
-- 
2.13.6

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