linux-kernel - [PATCH 2/2] mm/mm/damon/sysfs-schemes: reduce stack usage in damon_sysfs_mk

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Date:   Sun, 16 Jul 2023 09:09:27 +0800
From:   Chao Yu <chao@...nel.org>
To:     sj@...nel.org, akpm@...ux-foundation.org, damon@...ts.linux.dev
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Chao Yu <chao@...nel.org>
Subject: [PATCH 2/2] mm/mm/damon/sysfs-schemes: reduce stack usage in damon_sysfs_mk_scheme()

struct damos_quota quota caused the stack usage of damon_sysfs_mk_scheme()
to grow beyond the warning limit on 32-bit architectures w/ gcc.

mm/damon/sysfs-schemes.c: In function ‘damon_sysfs_mk_scheme’:
mm/damon/sysfs-schemes.c:1526:1: warning: the frame size of 1280 bytes is larger than 1024 bytes [-Wframe-larger-than=]

Allocating dynamic memory in damon_sysfs_mk_scheme() to fix this issue.

Signed-off-by: Chao Yu <chao@...nel.org>
---
 mm/damon/sysfs-schemes.c | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 50cf89dcd898..35fa1b421c26 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -1486,6 +1486,7 @@ static struct damos *damon_sysfs_mk_scheme(
 	struct damon_sysfs_scheme_filters *sysfs_filters =
 		sysfs_scheme->filters;
 	struct damos *scheme;
+	struct damos_quota *quota;
 	int err;
 
 	struct damos_access_pattern pattern = {
@@ -1496,14 +1497,6 @@ static struct damos *damon_sysfs_mk_scheme(
 		.min_age_region = access_pattern->age->min,
 		.max_age_region = access_pattern->age->max,
 	};
-	struct damos_quota quota = {
-		.ms = sysfs_quotas->ms,
-		.sz = sysfs_quotas->sz,
-		.reset_interval = sysfs_quotas->reset_interval_ms,
-		.weight_sz = sysfs_weights->sz,
-		.weight_nr_accesses = sysfs_weights->nr_accesses,
-		.weight_age = sysfs_weights->age,
-	};
 	struct damos_watermarks wmarks = {
 		.metric = sysfs_wmarks->metric,
 		.interval = sysfs_wmarks->interval_us,
@@ -1512,16 +1505,32 @@ static struct damos *damon_sysfs_mk_scheme(
 		.low = sysfs_wmarks->low,
 	};
 
-	scheme = damon_new_scheme(&pattern, sysfs_scheme->action, &quota,
+	quota = kmalloc(sizeof(struct damos_quota), GFP_KERNEL);
+	if (!quota)
+		return NULL;
+
+	quota->ms = sysfs_quotas->ms;
+	quota->sz = sysfs_quotas->sz;
+	quota->reset_interval = sysfs_quotas->reset_interval_ms;
+	quota->weight_sz = sysfs_weights->sz;
+	quota->weight_nr_accesses = sysfs_weights->nr_accesses;
+	quota->weight_age = sysfs_weights->age;
+
+	scheme = damon_new_scheme(&pattern, sysfs_scheme->action, quota,
 			&wmarks);
-	if (!scheme)
+	if (!scheme) {
+		kfree(quota);
 		return NULL;
+	}
 
 	err = damon_sysfs_set_scheme_filters(scheme, sysfs_filters);
 	if (err) {
+		kfree(quota);
 		damon_destroy_scheme(scheme);
 		return NULL;
 	}
+
+	kfree(quota);
 	return scheme;
 }
 
-- 
2.40.1