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To:     linux-mm@kvack.org, akpm@linux-foundation.org,
        linux-fsdevel@vger.kernel.org, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, naoya.horiguchi@nec.com,
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Cc:     joao.m.martins@oracle.com, rdunlap@infradead.org,
        sean.j.christopherson@intel.com, xiaoguangrong.eric@gmail.com,
        kernellwp@gmail.com, lihaiwei.kernel@gmail.com,
        Yulei Zhang <yuleixzhang@tencent.com>,
        Xiao Guangrong <gloryxiao@tencent.com>
Subject: [RFC V2 08/37] dmem: show some statistic in debugfs
Date:   Mon,  7 Dec 2020 19:31:01 +0800
Message-Id: <bdd885acf956dadb6822569160aa83258b6eeccc.1607332046.git.yuleixzhang@tencent.com>
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From: Yulei Zhang <yuleixzhang@tencent.com>

Create 'dmem' directory under debugfs and show some
statistic for dmem pool, track total and free dpages
on dmem pool and each numa node.

Signed-off-by: Xiao Guangrong <gloryxiao@tencent.com>
Signed-off-by: Yulei Zhang <yuleixzhang@tencent.com>
---
 mm/Kconfig |   8 +++++
 mm/dmem.c  | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 107 insertions(+), 1 deletion(-)

diff --git a/mm/Kconfig b/mm/Kconfig
index 3a6d408..4dd8896 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -234,6 +234,14 @@ config DMEM
 	  Allow reservation of memory which could be for the dedicated use of dmem.
 	  It's the basis of dmemfs.
 
+config DMEM_DEBUG_FS
+	bool "Enable debug information for direct memory"
+	depends on DMEM && DEBUG_FS
+	help
+	  This option enables showing various statistics of direct memory
+	  in debugfs filesystem.
+
+#
 # support for memory compaction
 config COMPACTION
 	bool "Allow for memory compaction"
diff --git a/mm/dmem.c b/mm/dmem.c
index aa34bf2..6992e57 100644
--- a/mm/dmem.c
+++ b/mm/dmem.c
@@ -164,6 +164,103 @@ int dmem_region_register(int node, phys_addr_t start, phys_addr_t end)
 	return 0;
 }
 
+#ifdef CONFIG_DMEM_DEBUG_FS
+struct debugfs_entry {
+	const char *name;
+	unsigned long offset;
+};
+
+#define DMEM_POOL_OFFSET(x)	offsetof(struct dmem_pool, x)
+#define DMEM_POOL_ENTRY(x)	{__stringify(x), DMEM_POOL_OFFSET(x)}
+
+#define DMEM_NODE_OFFSET(x)	offsetof(struct dmem_node, x)
+#define DMEM_NODE_ENTRY(x)	{__stringify(x), DMEM_NODE_OFFSET(x)}
+
+static struct debugfs_entry dmem_pool_entries[] = {
+	DMEM_POOL_ENTRY(region_num),
+	DMEM_POOL_ENTRY(registered_pages),
+	DMEM_POOL_ENTRY(unaligned_pages),
+	DMEM_POOL_ENTRY(dpage_shift),
+	DMEM_POOL_ENTRY(total_dpages),
+	DMEM_POOL_ENTRY(free_dpages),
+};
+
+static struct debugfs_entry dmem_node_entries[] = {
+	DMEM_NODE_ENTRY(total_dpages),
+	DMEM_NODE_ENTRY(free_dpages),
+};
+
+static int dmem_entry_get(void *offset, u64 *val)
+{
+	*val = *(u64 *)offset;
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(dmem_fops, dmem_entry_get, NULL, "%llu\n");
+
+static int dmemfs_init_debugfs_node(struct dmem_node *dnode,
+				    struct dentry *parent)
+{
+	struct dentry *node_dir;
+	char dir_name[32];
+	int i, ret = -EEXIST;
+
+	snprintf(dir_name, sizeof(dir_name), "node%ld",
+		 dnode - dmem_pool.nodes);
+	node_dir = debugfs_create_dir(dir_name, parent);
+	if (!node_dir)
+		return ret;
+
+	for (i = 0; i < ARRAY_SIZE(dmem_node_entries); i++)
+		if (!debugfs_create_file(dmem_node_entries[i].name, 0444,
+		   node_dir, (void *)dnode + dmem_node_entries[i].offset,
+		   &dmem_fops))
+			return ret;
+	return 0;
+}
+
+static int dmemfs_init_debugfs(void)
+{
+	struct dentry *dmem_debugfs_dir;
+	struct dmem_node *dnode;
+	int i, ret = -EEXIST;
+
+	dmem_debugfs_dir = debugfs_create_dir("dmem", NULL);
+	if (!dmem_debugfs_dir)
+		return ret;
+
+	for (i = 0; i < ARRAY_SIZE(dmem_pool_entries); i++)
+		if (!debugfs_create_file(dmem_pool_entries[i].name, 0444,
+		   dmem_debugfs_dir,
+		   (void *)&dmem_pool + dmem_pool_entries[i].offset,
+		   &dmem_fops))
+			goto exit;
+
+	for_each_dmem_node(dnode) {
+		/*
+		 * do not create debugfs files for the node
+		 * where no memory is available
+		 */
+		if (list_empty(&dnode->regions))
+			continue;
+
+		if (dmemfs_init_debugfs_node(dnode, dmem_debugfs_dir))
+			goto exit;
+	}
+
+	return 0;
+exit:
+	debugfs_remove_recursive(dmem_debugfs_dir);
+	return ret;
+}
+
+#else
+static int dmemfs_init_debugfs(void)
+{
+	return 0;
+}
+#endif
+
 #define PENALTY_FOR_DMEM_SHARED_NODE		(1)
 
 static int dmem_nodeload[MAX_NUMNODES] __initdata;
@@ -364,7 +461,8 @@ static int __init dmem_late_init(void)
 				goto exit;
 		}
 	}
-	return ret;
+
+	return dmemfs_init_debugfs();
 exit:
 	dmem_uinit();
 	return ret;
-- 
1.8.3.1