From: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx>
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@xxxxxxxxxx>
---
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
