[RFC PATCH] mm: sort kmemleak object via backtrace

* [RFC PATCH] mm: sort kmemleak object via backtrace
@ 2022-09-27  7:42 zhaoyang.huang
  2022-09-27  7:53 ` Zhaoyang Huang
                   ` (3 more replies)
  0 siblings, 4 replies; 6+ messages in thread
From: zhaoyang.huang @ 2022-09-27  7:42 UTC (permalink / raw)
  To: Andrew Morton, Catalin Marinas, Matthew Wilcox,
	Nathan Chancellor, Nick Desaulniers, Tom Rix, Zhaoyang Huang,
	linux-mm, linux-kernel, ke.wang, steve.kang

From: Zhaoyang Huang <zhaoyang.huang@unisoc.com>

Kmemleak objects are reported each which could produce lot of redundant
backtrace informations. introduce a set of method to establish a hash
tree to sort the objects according to backtrace.

results:
[  579.075111]c6 [ T5491] kmemleak: unreferenced object 0xffffff80badd9e00 (size 128):
[  579.082734]c6 [ T5491] kmemleak:   comm "swapper/0", pid 1, jiffies 4294892470
[  579.096837]c6 [ T5491] kmemleak: unreferenced object 0xffffff80badd9d00 (size 128):
[  579.104435]c6 [ T5491] kmemleak:   comm "swapper/0", pid 1, jiffies 4294892470
[  579.118563]c6 [ T5491] kmemleak: unreferenced object 0xffffff80baddce80 (size 128):
[  579.126201]c6 [ T5491] kmemleak:   comm "swapper/0", pid 1, jiffies 4294892470
[  579.140303]c6 [ T5491] kmemleak: unreferenced object 0xffffff80baddcb00 (size 128):
[  579.147906]c6 [ T5491] kmemleak:   comm "swapper/0", pid 1, jiffies 4294892470
[  579.162032]c6 [ T5491] kmemleak: unreferenced object 0xffffff80bae74a80 (size 128):
[  579.169661]c6 [ T5491] kmemleak:   comm "swapper/0", pid 1, jiffies 4294892470
[  579.183775]c6 [ T5491] kmemleak: unreferenced object 0xffffff80bae74100 (size 128):
[  579.191374]c6 [ T5491] kmemleak:   comm "swapper/0", pid 1, jiffies 4294892471
[  579.205486]c6 [ T5491] kmemleak: unreferenced object 0xffffff80bae75880 (size 128):
[  579.213127]c6 [ T5491] kmemleak:   comm "swapper/0", pid 1, jiffies 4294892471
[  579.227743]c6 [ T5491] kmemleak:   backtrace:
[  579.232109]c6 [ T5491] kmemleak:     [<0000000066492d96>] __kmalloc_track_caller+0x1d4/0x3e0
[  579.240506]c6 [ T5491] kmemleak:     [<00000000e5400df8>] kstrdup_const+0x6c/0xa4
[  579.247930]c6 [ T5491] kmemleak:     [<00000000d7843951>] __kernfs_new_node+0x5c/0x1dc
[  579.255830]c6 [ T5491] kmemleak:     [<0000000073b5a7bd>] kernfs_new_node+0x60/0xc4
[  579.263436]c6 [ T5491] kmemleak:     [<000000002c7a48d5>] __kernfs_create_file+0x60/0xfc
[  579.271485]c6 [ T5491] kmemleak:     [<00000000260ae4a1>] cgroup_addrm_files+0x244/0x4b0
[  579.279534]c6 [ T5491] kmemleak:     [<00000000ec6bce51>] css_populate_dir+0xb4/0x13c
[  579.287324]c6 [ T5491] kmemleak:     [<000000005913d698>] cgroup_mkdir+0x1e0/0x31c
[  579.294859]c6 [ T5491] kmemleak:     [<0000000052605ead>] kernfs_iop_mkdir.llvm.8836999160598622324+0xb0/0x168
[  579.304817]c6 [ T5491] kmemleak:     [<0000000009665bc4>] vfs_mkdir+0xec/0x170
[  579.311990]c6 [ T5491] kmemleak:     [<000000003c9c94c1>] do_mkdirat+0xa4/0x168
[  579.319279]c6 [ T5491] kmemleak:     [<000000005dd5be19>] __arm64_sys_mkdirat+0x28/0x38
[  579.327242]c6 [ T5491] kmemleak:     [<000000005a0b9381>] el0_svc_common+0xb4/0x188
[  579.334868]c6 [ T5491] kmemleak:     [<0000000063586a51>] el0_svc_handler+0x2c/0x3c
[  579.342472]c6 [ T5491] kmemleak:     [<00000000edfd67aa>] el0_svc+0x8/0x100

Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
---
 mm/kmemleak.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 97 insertions(+), 1 deletion(-)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 1eddc01..34134e5 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -102,6 +102,8 @@
 #include <linux/kfence.h>
 #include <linux/kmemleak.h>
 #include <linux/memory_hotplug.h>
+#include <linux/jhash.h>
+#include <linux/random.h>
 
 /*
  * Kmemleak configuration and common defines.
@@ -143,6 +145,7 @@ struct kmemleak_object {
 	unsigned int flags;		/* object status flags */
 	struct list_head object_list;
 	struct list_head gray_list;
+	struct list_head report_list;
 	struct rb_node rb_node;
 	struct rcu_head rcu;		/* object_list lockless traversal */
 	/* object usage count; object freed when use_count == 0 */
@@ -161,11 +164,18 @@ struct kmemleak_object {
 	struct hlist_head area_list;
 	unsigned long trace[MAX_TRACE];
 	unsigned int trace_len;
+	u32 trace_hash;
 	unsigned long jiffies;		/* creation timestamp */
 	pid_t pid;			/* pid of the current task */
 	char comm[TASK_COMM_LEN];	/* executable name */
 };
 
+struct kmemleak_report {
+	u32 trace_hash;
+	struct list_head report_list_head;
+	struct rb_node rb_node_report;
+	struct list_head *report_pos;
+};
 /* flag representing the memory block allocation status */
 #define OBJECT_ALLOCATED	(1 << 0)
 /* flag set after the first reporting of an unreference object */
@@ -195,10 +205,13 @@ struct kmemleak_object {
 static struct kmemleak_object mem_pool[CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE];
 static int mem_pool_free_count = ARRAY_SIZE(mem_pool);
 static LIST_HEAD(mem_pool_free_list);
+static struct kmemleak_report kr_pool[CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE];
+static int kr_pool_free_count = ARRAY_SIZE(kr_pool);
 /* search tree for object boundaries */
 static struct rb_root object_tree_root = RB_ROOT;
 /* search tree for object (with OBJECT_PHYS flag) boundaries */
 static struct rb_root object_phys_tree_root = RB_ROOT;
+static struct rb_root object_report_tree_root = RB_ROOT;
 /* protecting the access to object_list, object_tree_root (or object_phys_tree_root) */
 static DEFINE_RAW_SPINLOCK(kmemleak_lock);
 
@@ -241,6 +254,7 @@ struct kmemleak_object {
 
 static void kmemleak_disable(void);
 
+static u32 trace_seed;
 /*
  * Print a warning and dump the stack trace.
  */
@@ -423,6 +437,46 @@ static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
 	return __lookup_object(ptr, alias, false);
 }
 
+void print_unreferenced_object_list(struct seq_file *seq)
+{
+	unsigned long flags;
+	struct kmemleak_object *object;
+	struct kmemleak_report *object_report;
+	int i;
+	struct rb_node *rb;
+	bool reported_flag = false;
+
+	rcu_read_lock();
+	raw_spin_lock_irqsave(&kmemleak_lock, flags);
+	for (rb = rb_first(&object_report_tree_root); rb; rb = rb_next(rb)) {
+		object_report = rb_entry(rb, struct kmemleak_report, rb_node_report);
+		if (object_report && !list_empty(&object_report->report_list_head)) {
+			list_for_each_entry_rcu(object, &object_report->report_list_head, report_list) {
+				raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
+				raw_spin_lock_irqsave(&kmemleak_lock, flags);
+				if (unreferenced_object(object) &&
+						(object->flags & OBJECT_REPORTED)) {
+					reported_flag = true;
+					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\n",
+							object->comm, object->pid, object->jiffies);
+				}
+			}
+			if (reported_flag) {
+				warn_or_seq_printf(seq, "  backtrace:\n");
+				object = list_prev_entry(object, report_list);
+				for (i = 0; i < object->trace_len; i++) {
+					void *ptr = (void *)object->trace[i];
+					warn_or_seq_printf(seq, "    [<%p>] %pS\n", ptr, ptr);
+				}
+				reported_flag = false;
+			}
+		}
+	}
+	raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
+	rcu_read_unlock();
+}
 /*
  * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
  * that once an object's use_count reached 0, the RCU freeing was already
@@ -568,6 +622,7 @@ static void __remove_object(struct kmemleak_object *object)
 				   &object_phys_tree_root :
 				   &object_tree_root);
 	list_del_rcu(&object->object_list);
+	list_del_rcu(&object->report_list);
 }
 
 /*
@@ -610,9 +665,11 @@ static struct kmemleak_object *__create_object(unsigned long ptr, size_t size,
 {
 	unsigned long flags;
 	struct kmemleak_object *object, *parent;
+	struct kmemleak_report *report, *report_parent;
 	struct rb_node **link, *rb_parent;
 	unsigned long untagged_ptr;
 	unsigned long untagged_objp;
+	u32 trace_hash;
 
 	object = mem_pool_alloc(gfp);
 	if (!object) {
@@ -623,6 +680,7 @@ static struct kmemleak_object *__create_object(unsigned long ptr, size_t size,
 
 	INIT_LIST_HEAD(&object->object_list);
 	INIT_LIST_HEAD(&object->gray_list);
+	INIT_LIST_HEAD(&object->report_list);
 	INIT_HLIST_HEAD(&object->area_list);
 	raw_spin_lock_init(&object->lock);
 	atomic_set(&object->use_count, 1);
@@ -655,6 +713,7 @@ static struct kmemleak_object *__create_object(unsigned long ptr, size_t size,
 
 	/* kernel backtrace */
 	object->trace_len = __save_stack_trace(object->trace);
+	object->trace_hash = jhash2((const u32 *)object->trace, object->trace_len / sizeof(u32), trace_seed);
 
 	raw_spin_lock_irqsave(&kmemleak_lock, flags);
 
@@ -694,8 +753,42 @@ 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);
+
+	raw_spin_lock_irqsave(&kmemleak_lock, flags);
+	link = &object_report_tree_root.rb_node;
+	rb_parent = NULL;
+	while (*link) {
+		raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
+		raw_spin_lock_irqsave(&kmemleak_lock, flags);
+		rb_parent = *link;
+		report_parent = rb_entry(rb_parent, struct kmemleak_report, rb_node_report);
+		trace_hash = report_parent->trace_hash;
+		if (object->trace_hash < trace_hash)
+			link = &report_parent->rb_node_report.rb_left;
+		else if (trace_hash < object->trace_hash)
+			link = &report_parent->rb_node_report.rb_right;
+		else {
+			list_add_tail_rcu(&object->report_list, &report_parent->report_list_head);
+			goto out;
+		}
+	}
+	report = kr_pool_free_count ? &kr_pool[--kr_pool_free_count] : NULL;
+	if (!report)
+		goto out;
+	report->trace_hash = object->trace_hash;
+	/*
+	 * report is the 1st node represent this trace_hash, init its list_head and
+	 * insert it to object_report_tree_root
+	 */
+	INIT_LIST_HEAD(&report->report_list_head);
+	/* record 1st object to the list*/
+	list_add_tail_rcu(&object->report_list, &report->report_list_head);
+	/* initialize the report_pos as report_list_head*/
+	report->report_pos = &report->report_list_head;
+	/* add the node to rb tree*/
+	rb_link_node(&report->rb_node_report, rb_parent, link);
+	rb_insert_color(&report->rb_node_report, &object_report_tree_root);
 out:
 	raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
 	return object;
@@ -1947,6 +2040,8 @@ static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
 		kmemleak_scan();
 	else if (strncmp(buf, "dump=", 5) == 0)
 		ret = dump_str_object_info(buf + 5);
+	else if (strncmp(buf, "report", 6) == 0)
+		print_unreferenced_object_list(NULL);
 	else
 		ret = -EINVAL;
 
@@ -2080,6 +2175,7 @@ void __init kmemleak_init(void)
 		create_object((unsigned long)__start_ro_after_init,
 			      __end_ro_after_init - __start_ro_after_init,
 			      KMEMLEAK_GREY, GFP_ATOMIC);
+	get_random_bytes(&trace_seed, 4);
 }
 
 /*
-- 
1.9.1


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