mem-hotplug: avoid multiple zones sharing same boot strapping boot_pageset

For each new populated zone of hotadded node, need to update its pagesets
with dynamically allocated per_cpu_pageset struct for all possible CPUs:

    1) Detach zone->pageset from the shared boot_pageset
       at end of __build_all_zonelists().

    2) Use mutex to protect zone->pageset when it's still
       shared in onlined_pages()

Otherwises, multiple zones of different nodes would share same boot strapping
boot_pageset for same CPU, which will finally cause below kernel panic:

  ------------[ cut here ]------------
  kernel BUG at mm/page_alloc.c:1239!
  invalid opcode: 0000 [#1] SMP
  ...
  Call Trace:
   [<ffffffff811300c1>] __alloc_pages_nodemask+0x131/0x7b0
   [<ffffffff81162e67>] alloc_pages_current+0x87/0xd0
   [<ffffffff81128407>] __page_cache_alloc+0x67/0x70
   [<ffffffff811325f0>] __do_page_cache_readahead+0x120/0x260
   [<ffffffff81132751>] ra_submit+0x21/0x30
   [<ffffffff811329c6>] ondemand_readahead+0x166/0x2c0
   [<ffffffff81132ba0>] page_cache_async_readahead+0x80/0xa0
   [<ffffffff8112a0e4>] generic_file_aio_read+0x364/0x670
   [<ffffffff81266cfa>] nfs_file_read+0xca/0x130
   [<ffffffff8117b20a>] do_sync_read+0xfa/0x140
   [<ffffffff8117bf75>] vfs_read+0xb5/0x1a0
   [<ffffffff8117c151>] sys_read+0x51/0x80
   [<ffffffff8103c032>] system_call_fastpath+0x16/0x1b
  RIP  [<ffffffff8112ff13>] get_page_from_freelist+0x883/0x900
   RSP <ffff88000d1e78a8>
  ---[ end trace 4bda28328b9990db ]

[akpm@linux-foundation.org: merge fix]
Signed-off-by: Haicheng Li <haicheng.li@linux.intel.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Reviewed-by: Andi Kleen <andi.kleen@intel.com>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/mmzone.h

@@ -652,7 +652,7 @@ typedef struct pglist_data {
 
 void get_zone_counts(unsigned long *active, unsigned long *inactive,
 			unsigned long *free);
-void build_all_zonelists(void);
+void build_all_zonelists(void *data);
 void wakeup_kswapd(struct zone *zone, int order);
 int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
 		int classzone_idx, int alloc_flags);

init/main.c

@@ -567,7 +567,7 @@ asmlinkage void __init start_kernel(void)
 	setup_per_cpu_areas();
 	smp_prepare_boot_cpu();	/* arch-specific boot-cpu hooks */
 
-	build_all_zonelists();
+	build_all_zonelists(NULL);
 	page_alloc_init();
 
 	printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);

kernel/cpu.c

@@ -358,7 +358,7 @@ int __cpuinit cpu_up(unsigned int cpu)
 	}
 
 	if (pgdat->node_zonelists->_zonerefs->zone == NULL)
-		build_all_zonelists();
+		build_all_zonelists(NULL);
 #endif
 
 	cpu_maps_update_begin();

mm/memory_hotplug.c

@@ -389,6 +389,11 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
 	int nid;
 	int ret;
 	struct memory_notify arg;
+	/*
+	 * mutex to protect zone->pageset when it's still shared
+	 * in onlined_pages()
+	 */
+	static DEFINE_MUTEX(zone_pageset_mutex);
 
 	arg.start_pfn = pfn;
 	arg.nr_pages = nr_pages;
@@ -415,12 +420,14 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
 	 * This means the page allocator ignores this zone.
 	 * So, zonelist must be updated after online.
 	 */
+	mutex_lock(&zone_pageset_mutex);
 	if (!populated_zone(zone))
 		need_zonelists_rebuild = 1;
 
 	ret = walk_system_ram_range(pfn, nr_pages, &onlined_pages,
 		online_pages_range);
 	if (ret) {
+		mutex_unlock(&zone_pageset_mutex);
 		printk(KERN_DEBUG "online_pages %lx at %lx failed\n",
 			nr_pages, pfn);
 		memory_notify(MEM_CANCEL_ONLINE, &arg);
@@ -429,8 +436,12 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
 
 	zone->present_pages += onlined_pages;
 	zone->zone_pgdat->node_present_pages += onlined_pages;
+	if (need_zonelists_rebuild)
+		build_all_zonelists(zone);
+	else
+		zone_pcp_update(zone);
 
-	zone_pcp_update(zone);
+	mutex_unlock(&zone_pageset_mutex);
 	setup_per_zone_wmarks();
 	calculate_zone_inactive_ratio(zone);
 	if (onlined_pages) {
@@ -438,10 +449,7 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
 		node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
 	}
 
-	if (need_zonelists_rebuild)
-		build_all_zonelists();
-	else
-		vm_total_pages = nr_free_pagecache_pages();
+	vm_total_pages = nr_free_pagecache_pages();
 
 	writeback_set_ratelimit();
 

mm/page_alloc.c

@@ -2572,7 +2572,7 @@ int numa_zonelist_order_handler(ctl_table *table, int write,
 				NUMA_ZONELIST_ORDER_LEN);
 			user_zonelist_order = oldval;
 		} else if (oldval != user_zonelist_order)
-			build_all_zonelists();
+			build_all_zonelists(NULL);
 	}
 out:
 	mutex_unlock(&zl_order_mutex);
@@ -2922,9 +2922,10 @@ static void build_zonelist_cache(pg_data_t *pgdat)
  */
 static void setup_pageset(struct per_cpu_pageset *p, unsigned long batch);
 static DEFINE_PER_CPU(struct per_cpu_pageset, boot_pageset);
+static void setup_zone_pageset(struct zone *zone);
 
 /* return values int ....just for stop_machine() */
-static int __build_all_zonelists(void *dummy)
+static __init_refok int __build_all_zonelists(void *data)
 {
 	int nid;
 	int cpu;
@@ -2939,6 +2940,14 @@ static int __build_all_zonelists(void *dummy)
 		build_zonelist_cache(pgdat);
 	}
 
+#ifdef CONFIG_MEMORY_HOTPLUG
+	/* Setup real pagesets for the new zone */
+	if (data) {
+		struct zone *zone = data;
+		setup_zone_pageset(zone);
+	}
+#endif
+
 	/*
 	 * Initialize the boot_pagesets that are going to be used
 	 * for bootstrapping processors. The real pagesets for
@@ -2958,7 +2967,7 @@ static int __build_all_zonelists(void *dummy)
 	return 0;
 }
 
-void build_all_zonelists(void)
+void build_all_zonelists(void *data)
 {
 	set_zonelist_order();
 
@@ -2969,7 +2978,7 @@ void build_all_zonelists(void)
 	} else {
 		/* we have to stop all cpus to guarantee there is no user
 		   of zonelist */
-		stop_machine(__build_all_zonelists, NULL, NULL);
+		stop_machine(__build_all_zonelists, data, NULL);
 		/* cpuset refresh routine should be here */
 	}
 	vm_total_pages = nr_free_pagecache_pages();