[PATCH v2 5/6] mm/slub: sort debugfs output by frequency of stack traces

From: Vlastimil Babka
Date: Wed Mar 02 2022 - 12:32:50 EST


From: Oliver Glitta <glittao@xxxxxxxxx>

Sort the output of debugfs alloc_traces and free_traces by the frequency
of allocation/freeing stack traces. Most frequently used stack traces
will be printed first, e.g. for easier memory leak debugging.

Signed-off-by: Oliver Glitta <glittao@xxxxxxxxx>
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Reviewed-and-tested-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
---
mm/slub.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/mm/slub.c b/mm/slub.c
index 25138cd7a4ef..39da762fbceb 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -38,6 +38,7 @@
#include <linux/memcontrol.h>
#include <linux/random.h>
#include <kunit/test.h>
+#include <linux/sort.h>

#include <linux/debugfs.h>
#include <trace/events/kmem.h>
@@ -6149,6 +6150,17 @@ 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)
+{
+ struct location *loc1 = (struct location *)a;
+ struct location *loc2 = (struct location *)b;
+
+ if (loc1->count > loc2->count)
+ return -1;
+ else
+ return 1;
+}
+
static void *slab_debugfs_start(struct seq_file *seq, loff_t *ppos)
{
struct loc_track *t = seq->private;
@@ -6210,6 +6222,10 @@ static int slab_debug_trace_open(struct inode *inode, struct file *filep)
spin_unlock_irqrestore(&n->list_lock, flags);
}

+ /* Sort locations by count */
+ sort_r(t->loc, t->count, sizeof(struct location),
+ cmp_loc_by_count, NULL, NULL);
+
bitmap_free(obj_map);
return 0;
}
--
2.35.1