mm: vmalloc: support multiple nodes in vmallocinfo

Allocated areas are spread among nodes, it implies that the scanning has
to be performed individually of each node in order to dump all existing
VAs.

Link: https://lkml.kernel.org/r/20240102184633.748113-10-urezki@gmail.comSigned-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Kazuhito Hagio <k-hagio-ab@nec.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sony.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmalloc.c

@@ -4709,30 +4709,6 @@ bool vmalloc_dump_obj(void *object)
 #endif
 
 #ifdef CONFIG_PROC_FS
-static void *s_start(struct seq_file *m, loff_t *pos)
-{
-	struct vmap_node *vn = addr_to_node(0);
-
-	mutex_lock(&vmap_purge_lock);
-	spin_lock(&vn->busy.lock);
-
-	return seq_list_start(&vn->busy.head, *pos);
-}
-
-static void *s_next(struct seq_file *m, void *p, loff_t *pos)
-{
-	struct vmap_node *vn = addr_to_node(0);
-	return seq_list_next(p, &vn->busy.head, pos);
-}
-
-static void s_stop(struct seq_file *m, void *p)
-{
-	struct vmap_node *vn = addr_to_node(0);
-
-	spin_unlock(&vn->busy.lock);
-	mutex_unlock(&vmap_purge_lock);
-}
-
 static void show_numa_info(struct seq_file *m, struct vm_struct *v)
 {
 	if (IS_ENABLED(CONFIG_NUMA)) {
@@ -4776,22 +4752,25 @@ static void show_purge_info(struct seq_file *m)
 	}
 }
 
-static int s_show(struct seq_file *m, void *p)
+static int vmalloc_info_show(struct seq_file *m, void *p)
 {
 	struct vmap_node *vn;
 	struct vmap_area *va;
 	struct vm_struct *v;
+	int i;
 
-	vn = addr_to_node(0);
-	va = list_entry(p, struct vmap_area, list);
+	for (i = 0; i < nr_vmap_nodes; i++) {
+		vn = &vmap_nodes[i];
 
+		spin_lock(&vn->busy.lock);
+		list_for_each_entry(va, &vn->busy.head, list) {
 			if (!va->vm) {
 				if (va->flags & VMAP_RAM)
 					seq_printf(m, "0x%pK-0x%pK %7ld vm_map_ram\n",
 						(void *)va->va_start, (void *)va->va_end,
 						va->va_end - va->va_start);
 
-		goto final;
+				continue;
 			}
 
 			v = va->vm;
@@ -4828,32 +4807,27 @@ static int s_show(struct seq_file *m, void *p)
 
 			show_numa_info(m, v);
 			seq_putc(m, '\n');
+		}
+		spin_unlock(&vn->busy.lock);
+	}
 
 	/*
 	 * As a final step, dump "unpurged" areas.
 	 */
-final:
-	if (list_is_last(&va->list, &vn->busy.head))
 	show_purge_info(m);
-
 	return 0;
 }
 
-static const struct seq_operations vmalloc_op = {
-	.start = s_start,
-	.next = s_next,
-	.stop = s_stop,
-	.show = s_show,
-};
-
 static int __init proc_vmalloc_init(void)
 {
+	void *priv_data = NULL;
+
 	if (IS_ENABLED(CONFIG_NUMA))
-		proc_create_seq_private("vmallocinfo", 0400, NULL,
-				&vmalloc_op,
-				nr_node_ids * sizeof(unsigned int), NULL);
-	else
-		proc_create_seq("vmallocinfo", 0400, NULL, &vmalloc_op);
+		priv_data = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL);
+
+	proc_create_single_data("vmallocinfo",
+		0400, NULL, vmalloc_info_show, priv_data);
+
 	return 0;
 }
 module_init(proc_vmalloc_init);