[PATCH mm-next] alloc_tag: add total bytes allocation information

[LiZetao <lizetao.kernel@gmail.com>]

From bb3537ee638ac80eebcfe9160961e36df8d3ee4c Mon Sep 17 00:00:00 2001
From: Li Zetao <lizetao.kernel@gmail.com>
Date: Tue, 1 Jul 2025 09:30:16 +0000
Subject: [PATCH mm-next] alloc_tag: add total bytes allocation information

Some performance monitoring tools focus on real-time memory
usage anddisplay the total amount of memory applied, which is
convenient for analyzing the memory usage ratio.

Added total information in /proc/allocinfo to feedback the
total amount of memory applied to the user. Example is as
follows:

root:~# cat /proc/allocinfo|tail
       98112      168 lib/radix-tree.c:338 func:__radix_tree_preload
       12848       22 lib/radix-tree.c:276 func:radix_tree_node_alloc
      300760      515 lib/radix-tree.c:253 func:radix_tree_node_alloc
           0        0 lib/xarray.c:1214 func:xas_try_split
           0        0 lib/xarray.c:1059 func:xas_split_alloc
      208488      357 lib/xarray.c:378 func:xas_alloc
           0        0 lib/xarray.c:344 func:__xas_nomem
           0        0 lib/xarray.c:341 func:__xas_nomem
           0        0 lib/xarray.c:309 func:xas_nomem
total: 102208196

Signed-off-by: Li Zetao <lizetao.kernel@gmail.com>
---
 lib/alloc_tag.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
index e9b33848700a..e4e41317a4b7 100644
--- a/lib/alloc_tag.c
+++ b/lib/alloc_tag.c
@@ -43,6 +43,7 @@ int alloc_tag_ref_offs;
 struct allocinfo_private {
  struct codetag_iterator iter;
  bool print_header;
+ long long total;
 };

 static void *allocinfo_start(struct seq_file *m, loff_t *pos)
@@ -53,6 +54,7 @@ static void *allocinfo_start(struct seq_file *m, loff_t *pos)
  priv = (struct allocinfo_private *)m->private;
  codetag_lock_module_list(alloc_tag_cttype, true);
  if (node == 0) {
+ priv->total = 0;
  priv->print_header = true;
  priv->iter = codetag_get_ct_iter(alloc_tag_cttype);
  codetag_next_ct(&priv->iter);
@@ -66,8 +68,16 @@ static void *allocinfo_next(struct seq_file *m,
void *arg, loff_t *pos)
  struct codetag *ct = codetag_next_ct(&priv->iter);

  (*pos)++;
- if (!ct)
+ if (!ct) {
+ char *bufp;
+ size_t n = seq_get_buf(m, &bufp);
+ struct seq_buf buf;
+
+ seq_buf_init(&buf, bufp, n);
+ seq_buf_printf(&buf, "total: %llu\n", priv->total);
+ seq_commit(m, seq_buf_used(&buf));
  return NULL;
+ }

  return priv;
 }
@@ -84,11 +94,13 @@ static void print_allocinfo_header(struct seq_buf *buf)
  seq_buf_printf(buf, "#     <size>  <calls> <tag info>\n");
 }

-static void alloc_tag_to_text(struct seq_buf *out, struct codetag *ct)
+static void alloc_tag_to_text(struct seq_buf *out, struct
allocinfo_private *priv)
 {
+ struct codetag *ct = priv->iter.ct;
  struct alloc_tag *tag = ct_to_alloc_tag(ct);
  struct alloc_tag_counters counter = alloc_tag_read(tag);
  s64 bytes = counter.bytes;
+ priv->total += bytes;

  seq_buf_printf(out, "%12lli %8llu ", bytes, counter.calls);
  codetag_to_text(out, ct);
@@ -108,7 +120,7 @@ static int allocinfo_show(struct seq_file *m, void *arg)
  print_allocinfo_header(&buf);
  priv->print_header = false;
  }
- alloc_tag_to_text(&buf, priv->iter.ct);
+ alloc_tag_to_text(&buf, priv);
  seq_commit(m, seq_buf_used(&buf));
  return 0;
 }
-- 
2.34.1