2022-10-27 10:00:10

by zhaoyang.huang

Subject: [Resend PATCHv2] mm: use stack_depot for recording kmemleak's backtrace

From: Zhaoyang Huang <[email protected]>

Using stack_depot to record kmemleak's backtrace which has been implemented
on slub for reducing redundant information.

Signed-off-by: Zhaoyang Huang <[email protected]>
---
changes of v2: fix bugs of stack_depot_init related issue
---
---
mm/kmemleak.c | 45 +++++++++++++++++++++++++++++++++++----------
1 file changed, 35 insertions(+), 10 deletions(-)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 1eddc01..fdf0927 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -79,6 +79,7 @@
#include <linux/mutex.h>
#include <linux/rcupdate.h>
#include <linux/stacktrace.h>
+#include <linux/stackdepot.h>
#include <linux/cache.h>
#include <linux/percpu.h>
#include <linux/memblock.h>
@@ -159,8 +160,7 @@ struct kmemleak_object {
u32 checksum;
/* memory ranges to be scanned inside an object (empty for all) */
struct hlist_head area_list;
- unsigned long trace[MAX_TRACE];
- unsigned int trace_len;
+ depot_stack_handle_t trace_handle;
unsigned long jiffies; /* creation timestamp */
pid_t pid; /* pid of the current task */
char comm[TASK_COMM_LEN]; /* executable name */
@@ -346,8 +346,11 @@ static void print_unreferenced(struct seq_file *seq,
struct kmemleak_object *object)
{
int i;
+ unsigned long *entries;
+ unsigned int nr_entries;
unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);

+ nr_entries = stack_depot_fetch(object->trace_handle, &entries);
warn_or_seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
object->pointer, object->size);
warn_or_seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
@@ -356,10 +359,10 @@ static void print_unreferenced(struct seq_file *seq,
hex_dump_object(seq, object);
warn_or_seq_printf(seq, " backtrace:\n");

- for (i = 0; i < object->trace_len; i++) {
- void *ptr = (void *)object->trace[i];
- warn_or_seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
- }
+ for (i = 0; i < nr_entries; i++) {
+ void *ptr = (void *)entries[i];
+ warn_or_seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
+ }
}

/*
@@ -378,7 +381,8 @@ static void dump_object_info(struct kmemleak_object *object)
pr_notice(" flags = 0x%x\n", object->flags);
pr_notice(" checksum = %u\n", object->checksum);
pr_notice(" backtrace:\n");
- stack_trace_print(object->trace, object->trace_len, 4);
+ if(object->trace_handle)
+ stack_depot_print(object->trace_handle);
}

/*
@@ -591,6 +595,27 @@ static struct kmemleak_object *find_and_remove_object(unsigned long ptr, int ali
return object;
}

+#ifdef CONFIG_STACKDEPOT
+static noinline depot_stack_handle_t set_track_prepare(void)
+{
+ depot_stack_handle_t trace_handle;
+ unsigned long entries[MAX_TRACE];
+ unsigned int nr_entries;
+
+ if (!kmemleak_initialized)
+ return 0;
+ nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 3);
+ trace_handle = stack_depot_save(entries, nr_entries, GFP_NOWAIT);
+
+ return trace_handle;
+}
+#else
+static inline depot_stack_handle_t set_track_prepare(void)
+{
+ return 0;
+}
+#endif
+
/*
* Save stack trace to the given array of MAX_TRACE size.
*/
@@ -654,7 +679,7 @@ static struct kmemleak_object *__create_object(unsigned long ptr, size_t size,
}

/* kernel backtrace */
- object->trace_len = __save_stack_trace(object->trace);
+ object->trace_handle = set_track_prepare();

raw_spin_lock_irqsave(&kmemleak_lock, flags);

@@ -694,7 +719,6 @@ static struct kmemleak_object *__create_object(unsigned long ptr, size_t size,
rb_link_node(&object->rb_node, rb_parent, link);
rb_insert_color(&object->rb_node, is_phys ? &object_phys_tree_root :
&object_tree_root);
-
list_add_tail_rcu(&object->object_list, &object_list);
out:
raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
@@ -1094,7 +1118,7 @@ void __ref kmemleak_update_trace(const void *ptr)
}

raw_spin_lock_irqsave(&object->lock, flags);
- object->trace_len = __save_stack_trace(object->trace);
+ object->trace_handle = set_track_prepare();
raw_spin_unlock_irqrestore(&object->lock, flags);

put_object(object);
@@ -2064,6 +2088,7 @@ void __init kmemleak_init(void)
if (kmemleak_error)
return;

+ stack_depot_init();
jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);

--
1.9.1

2022-10-28 14:14:52

by Catalin Marinas

Subject: Re: [Resend PATCHv2] mm: use stack_depot for recording kmemleak's backtrace

On Thu, Oct 27, 2022 at 05:50:24PM +0800, zhaoyang.huang wrote:
> From: Zhaoyang Huang <[email protected]>
>
> Using stack_depot to record kmemleak's backtrace which has been implemented
> on slub for reducing redundant information.
>
> Signed-off-by: Zhaoyang Huang <[email protected]>

Acked-by: Catalin Marinas <[email protected]>