memory: move hotplug memory notifier priority to same file for easy sorting

The priority of hotplug memory callback is defined in a different file. 
And there are some callers using numbers directly.  Collect them together
into include/linux/memory.h for easy reading.  This allows us to sort
their priorities more intuitively without additional comments.

Link: https://lkml.kernel.org/r/20220923033347.3935160-9-liushixin2@huawei.com
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Waiman Long <longman@redhat.com>
Cc: zefan li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

drivers/acpi/numa/hmat.c

@@ -849,7 +849,7 @@ static __init int hmat_init(void)
 	hmat_register_targets();
 
 	/* Keep the table and structures if the notifier may use them */
-	if (!hotplug_memory_notifier(hmat_callback, 2))
+	if (!hotplug_memory_notifier(hmat_callback, HMAT_CALLBACK_PRI))
 		return 0;
 out_put:
 	hmat_free_structures();

fs/proc/kcore.c

@@ -689,7 +689,7 @@ static int __init proc_kcore_init(void)
 	add_modules_range();
 	/* Store direct-map area from physical memory map */
 	kcore_update_ram();
-	hotplug_memory_notifier(kcore_callback, 0);
+	hotplug_memory_notifier(kcore_callback, DEFAULT_CALLBACK_PRI);
 
 	return 0;
 }

include/linux/memory-tiers.h

@@ -18,7 +18,6 @@
  * the same memory tier.
  */
 #define MEMTIER_ADISTANCE_DRAM	((4 * MEMTIER_CHUNK_SIZE) + (MEMTIER_CHUNK_SIZE >> 1))
-#define MEMTIER_HOTPLUG_PRIO	100
 
 struct memory_tier;
 struct memory_dev_type {

include/linux/memory.h

@@ -112,8 +112,13 @@ struct mem_section;
  * Priorities for the hotplug memory callback routines (stored in decreasing
  * order in the callback chain)
  */
-#define SLAB_CALLBACK_PRI       1
-#define IPC_CALLBACK_PRI        10
+#define DEFAULT_CALLBACK_PRI	0
+#define SLAB_CALLBACK_PRI	1
+#define HMAT_CALLBACK_PRI	2
+#define MM_COMPUTE_BATCH_PRI	10
+#define CPUSET_CALLBACK_PRI	10
+#define MEMTIER_HOTPLUG_PRI	100
+#define KSM_CALLBACK_PRI	100
 
 #ifndef CONFIG_MEMORY_HOTPLUG
 static inline void memory_dev_init(void)

kernel/cgroup/cpuset.c

@@ -3647,7 +3647,7 @@ void __init cpuset_init_smp(void)
 	cpumask_copy(top_cpuset.effective_cpus, cpu_active_mask);
 	top_cpuset.effective_mems = node_states[N_MEMORY];
 
-	hotplug_memory_notifier(cpuset_track_online_nodes, 10);
+	hotplug_memory_notifier(cpuset_track_online_nodes, CPUSET_CALLBACK_PRI);
 
 	cpuset_migrate_mm_wq = alloc_ordered_workqueue("cpuset_migrate_mm", 0);
 	BUG_ON(!cpuset_migrate_mm_wq);

mm/kasan/shadow.c

@@ -244,7 +244,7 @@ static int __meminit kasan_mem_notifier(struct notifier_block *nb,
 
 static int __init kasan_memhotplug_init(void)
 {
-	hotplug_memory_notifier(kasan_mem_notifier, 0);
+	hotplug_memory_notifier(kasan_mem_notifier, DEFAULT_CALLBACK_PRI);
 
 	return 0;
 }

mm/ksm.c

@@ -3211,7 +3211,7 @@ static int __init ksm_init(void)
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
 	/* There is no significance to this priority 100 */
-	hotplug_memory_notifier(ksm_memory_callback, 100);
+	hotplug_memory_notifier(ksm_memory_callback, KSM_CALLBACK_PRI);
 #endif
 	return 0;
 

mm/memory-tiers.c

@@ -664,7 +664,7 @@ static int __init memory_tier_init(void)
 	establish_demotion_targets();
 	mutex_unlock(&memory_tier_lock);
 
-	hotplug_memory_notifier(memtier_hotplug_callback, MEMTIER_HOTPLUG_PRIO);
+	hotplug_memory_notifier(memtier_hotplug_callback, MEMTIER_HOTPLUG_PRI);
 	return 0;
 }
 subsys_initcall(memory_tier_init);

mm/mm_init.c

@@ -181,7 +181,7 @@ static int __meminit mm_compute_batch_notifier(struct notifier_block *self,
 static int __init mm_compute_batch_init(void)
 {
 	mm_compute_batch(sysctl_overcommit_memory);
-	hotplug_memory_notifier(mm_compute_batch_notifier, IPC_CALLBACK_PRI);
+	hotplug_memory_notifier(mm_compute_batch_notifier, MM_COMPUTE_BATCH_PRI);
 	return 0;
 }
 

mm/mmap.c

@@ -3751,7 +3751,7 @@ static int reserve_mem_notifier(struct notifier_block *nb,
 
 static int __meminit init_reserve_notifier(void)
 {
-	if (hotplug_memory_notifier(reserve_mem_notifier, 0))
+	if (hotplug_memory_notifier(reserve_mem_notifier, DEFAULT_CALLBACK_PRI))
 		pr_err("Failed registering memory add/remove notifier for admin reserve\n");
 
 	return 0;

mm/page_ext.c

@@ -513,7 +513,7 @@ void __init page_ext_init(void)
 			cond_resched();
 		}
 	}
-	hotplug_memory_notifier(page_ext_callback, 0);
+	hotplug_memory_notifier(page_ext_callback, DEFAULT_CALLBACK_PRI);
 	pr_info("allocated %ld bytes of page_ext\n", total_usage);
 	invoke_init_callbacks();
 	return;