On Mon, 31 Aug 2020 20:08:44 +0200 Marco Elver [off-list ref] wrote:

On Mon, Aug 31, 2020 at 12:47PM +0200, SeongJae Park wrote:
[...]

quoted

diff --git a/mm/damon.c b/mm/damon.c
index 7e3c8c82a010..9815d22fc4de 100644
--- a/mm/damon.c
+++ b/mm/damon.c

@@ -2001,6 +2001,147 @@ static ssize_t debugfs_record_write(struct file *file,
 	return ret;
 }
 
+static ssize_t sprint_init_regions(struct damon_ctx *c, char *buf, ssize_t len)
+{
+	struct damon_target *t;
+	struct damon_region *r;
+	int written = 0;
+	int rc;
+
+	damon_for_each_target(t, c) {
+		damon_for_each_region(r, t) {
+			rc = snprintf(&buf[written], len - written,
+					"%lu %lu %lu\n",
+					t->id, r->ar.start, r->ar.end);

This most likely will not work as intended, because snprintf() returns
"[...] the number of characters which would be generated for the given
input, excluding the trailing null [...]". Would scnprintf() -- which
returns "[...] the number of characters written into @buf not including
the trailing '\0' [...]" -- do what you intended?

Ah, you're right!  I will use 'scnprintf' instead, not only here but in other
relevant parts.


Thanks,
SeongJae Park

quoted

+			if (!rc)
+				return -ENOMEM;
+			written += rc;
+		}
+	}
+	return written;
+}

[...]