[PATCH v4] mm, hugetlb: skip irrelevant nodes in show_free_areas()

[Gang Li <ligang.bdlg@xxxxxxxxxxxxx>]

show_free_areas() allows to filter out node specific data which is
irrelevant to the allocation request. But hugetlb_show_meminfo() still
shows hugetlb on all nodes, which is redundant and unnecessary.

Use show_mem_node_skip() to skip irrelevant nodes. And replace
hugetlb_show_meminfo() with hugetlb_show_meminfo_node(nid).

before-and-after sample output of OOM:

before:
```
[  214.362453] Node 1 active_anon:148kB inactive_anon:4050920kB active_file:112kB inactive_file:100kB
[  214.375429] Node 1 Normal free:45100kB boost:0kB min:45576kB low:56968kB high:68360kB reserved_hig
[  214.388334] lowmem_reserve[]: 0 0 0 0 0
[  214.390251] Node 1 Normal: 423*4kB (UE) 320*8kB (UME) 187*16kB (UE) 117*32kB (UE) 57*64kB (UME) 20
[  214.397626] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
[  214.401518] Node 1 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
```

after:
```
[  145.069705] Node 1 active_anon:128kB inactive_anon:4049412kB active_file:56kB inactive_file:84kB u
[  145.110319] Node 1 Normal free:45424kB boost:0kB min:45576kB low:56968kB high:68360kB reserved_hig
[  145.152315] lowmem_reserve[]: 0 0 0 0 0
[  145.155244] Node 1 Normal: 470*4kB (UME) 373*8kB (UME) 247*16kB (UME) 168*32kB (UE) 86*64kB (UME) 
[  145.164119] Node 1 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
```

Signed-off-by: Gang Li <ligang.bdlg@xxxxxxxxxxxxx>
---
v3->v4:
 - add before-and-after sample output text. (Andrew Morton)

v2->v3:
 - move for_each_hstate() into hugetlb_show_meminfo_node(). (Muchun Song)

v1->v2:
 - replace hugetlb_show_meminfo() with hugetlb_show_meminfo_node(nid) to avoid
   exporting show_mem_node_skip. (Muchun Song)
---
 include/linux/hugetlb.h |  4 ++--
 mm/hugetlb.c            | 18 ++++++++----------
 mm/page_alloc.c         |  8 ++++++--
 3 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 29c4d0883d36..21795e62398b 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -155,7 +155,7 @@ void __unmap_hugepage_range_final(struct mmu_gather *tlb,
 			  struct page *ref_page, zap_flags_t zap_flags);
 void hugetlb_report_meminfo(struct seq_file *);
 int hugetlb_report_node_meminfo(char *buf, int len, int nid);
-void hugetlb_show_meminfo(void);
+void hugetlb_show_meminfo_node(int nid);
 unsigned long hugetlb_total_pages(void);
 vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 			unsigned long address, unsigned int flags);
@@ -301,7 +301,7 @@ static inline int hugetlb_report_node_meminfo(char *buf, int len, int nid)
 	return 0;
 }
 
-static inline void hugetlb_show_meminfo(void)
+static inline void hugetlb_show_meminfo_node(int nid)
 {
 }
 
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ca081078e814..e7f12edb120c 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4490,22 +4490,20 @@ int hugetlb_report_node_meminfo(char *buf, int len, int nid)
 			     nid, h->surplus_huge_pages_node[nid]);
 }
 
-void hugetlb_show_meminfo(void)
+void hugetlb_show_meminfo_node(int nid)
 {
 	struct hstate *h;
-	int nid;
 
 	if (!hugepages_supported())
 		return;
 
-	for_each_node_state(nid, N_MEMORY)
-		for_each_hstate(h)
-			pr_info("Node %d hugepages_total=%u hugepages_free=%u hugepages_surp=%u hugepages_size=%lukB\n",
-				nid,
-				h->nr_huge_pages_node[nid],
-				h->free_huge_pages_node[nid],
-				h->surplus_huge_pages_node[nid],
-				huge_page_size(h) / SZ_1K);
+	for_each_hstate(h)
+		printk("Node %d hugepages_total=%u hugepages_free=%u hugepages_surp=%u hugepages_size=%lukB\n",
+			nid,
+			h->nr_huge_pages_node[nid],
+			h->free_huge_pages_node[nid],
+			h->surplus_huge_pages_node[nid],
+			huge_page_size(h) / SZ_1K);
 }
 
 void hugetlb_report_usage(struct seq_file *m, struct mm_struct *mm)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2eb6ad5a650a..93f032f32812 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6014,7 +6014,7 @@ static void show_migration_types(unsigned char type)
 void show_free_areas(unsigned int filter, nodemask_t *nodemask)
 {
 	unsigned long free_pcp = 0;
-	int cpu;
+	int cpu, nid;
 	struct zone *zone;
 	pg_data_t *pgdat;
 
@@ -6202,7 +6202,11 @@ void show_free_areas(unsigned int filter, nodemask_t *nodemask)
 		printk(KERN_CONT "= %lukB\n", K(total));
 	}
 
-	hugetlb_show_meminfo();
+	for_each_online_node(nid) {
+		if (show_mem_node_skip(filter, nid, nodemask))
+			continue;
+		hugetlb_show_meminfo_node(nid);
+	}
 
 	printk("%ld total pagecache pages\n", global_node_page_state(NR_FILE_PAGES));
 
-- 
2.20.1