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mm: sort kmemleak object via backtrace
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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>
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@intel-lab-lkp
Zhaoyang Huang authored and intel-lab-lkp committed Sep 27, 2022
1 parent a137556 commit 0662227
Showing 1 changed file with 97 additions and 1 deletion.
98 changes: 97 additions & 1 deletion mm/kmemleak.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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.
Expand Down Expand Up @@ -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 */
Expand All @@ -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 */
Expand Down Expand Up @@ -195,10 +205,13 @@ static LIST_HEAD(gray_list);
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);

Expand Down Expand Up @@ -241,6 +254,7 @@ module_param_named(verbose, kmemleak_verbose, bool, 0600);

static void kmemleak_disable(void);

static u32 trace_seed;
/*
* Print a warning and dump the stack trace.
*/
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -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);
}

/*
Expand Down Expand Up @@ -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) {
Expand All @@ -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);
Expand Down Expand Up @@ -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);

Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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;

Expand Down Expand Up @@ -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);
}

/*
Expand Down

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