[v2] mm/slub: Fix debugfs stack trace sorting and simplify sort call

[PATCH v2 2/2] mm/slub: Replace sort_r() with sort() for debugfs stack trace sorting

Posted by Kuan-Wei Chiu 1 month, 1 week ago

The comparison function used to sort stack trace locations in debugfs
never relied on the third argument. Therefore, sort_r() is unnecessary.
Switch to sort() with a two-argument comparison function to keep the
code simple and aligned with the intended usage.

Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
---
 mm/slub.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 081816ff89ab..39a238384892 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -7711,7 +7711,7 @@ static void *slab_debugfs_next(struct seq_file *seq, void *v, loff_t *ppos)
 	return NULL;
 }
 
-static int cmp_loc_by_count(const void *a, const void *b, const void *data)
+static int cmp_loc_by_count(const void *a, const void *b)
 {
 	struct location *loc1 = (struct location *)a;
 	struct location *loc2 = (struct location *)b;
@@ -7778,8 +7778,8 @@ static int slab_debug_trace_open(struct inode *inode, struct file *filep)
 	}
 
 	/* Sort locations by count */
-	sort_r(t->loc, t->count, sizeof(struct location),
-		cmp_loc_by_count, NULL, NULL);
+	sort(t->loc, t->count, sizeof(struct location),
+	     cmp_loc_by_count, NULL);
 
 	bitmap_free(obj_map);
 	return 0;
-- 
2.34.1

Re: [PATCH v2 2/2] mm/slub: Replace sort_r() with sort() for debugfs stack trace sorting

Posted by Harry Yoo 1 month ago

On Tue, Aug 26, 2025 at 02:23:15PM +0800, Kuan-Wei Chiu wrote:
> The comparison function used to sort stack trace locations in debugfs
> never relied on the third argument. Therefore, sort_r() is unnecessary.
> Switch to sort() with a two-argument comparison function to keep the
> code simple and aligned with the intended usage.
> 
> Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
> ---

Reviewed-by: Harry Yoo <harry.yoo@oracle.com>

>  mm/slub.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index 081816ff89ab..39a238384892 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -7711,7 +7711,7 @@ static void *slab_debugfs_next(struct seq_file *seq, void *v, loff_t *ppos)
>  	return NULL;
>  }
>  
> -static int cmp_loc_by_count(const void *a, const void *b, const void *data)
> +static int cmp_loc_by_count(const void *a, const void *b)
>  {
>  	struct location *loc1 = (struct location *)a;
>  	struct location *loc2 = (struct location *)b;
> @@ -7778,8 +7778,8 @@ static int slab_debug_trace_open(struct inode *inode, struct file *filep)
>  	}
>  
>  	/* Sort locations by count */
> -	sort_r(t->loc, t->count, sizeof(struct location),
> -		cmp_loc_by_count, NULL, NULL);
> +	sort(t->loc, t->count, sizeof(struct location),
> +	     cmp_loc_by_count, NULL);
>  
>  	bitmap_free(obj_map);
>  	return 0;
> -- 
> 2.34.1
> 

-- 
Cheers,
Harry / Hyeonggon

[PATCH v2 1/2] mm/slub: Fix cmp_loc_by_count() to return 0 when counts are equal
[PATCH v2 2/2] mm/slub: Replace sort_r() with sort() for debugfs stack trace sorting