內存泄漏工具kmemleak 使用方法

1.kmemleak使用方法

https://www.cnblogs.com/arnoldlu/p/8568090.html

2.英文手冊

https://www.kernel.org/doc/html/latest/dev-tools/kmemleak.html

3.原理分析

http://blog.chinaunix.net/uid-26859697-id-5758036.html

參考上面3個文章，但是編譯內核以後，一直  /sys/kernel/debug/kmemleak 下找不到。後來發現開機log打印：

[    0.000000] kmemleak: Kernel memory leak detector disabled
[    0.000550] kmemleak: Early log buffer exceeded (1147), please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE

後續發現 .config中DEBUG_KMEMLEAK_EARLY_LOG_SIZE設置默認值爲400，更到到10000後運行正常。

實例如下：

1.寫出內存泄漏的相關代碼：

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/poll.h>
#include <linux/kthread.h>
#include <linux/slab.h>

struct task_struct *mem_alloc_kthread;
int memory_kthread_alloc(void *arg)
{
	char *buf = NULL;
	while(!kthread_should_stop()) {
		buf = kmalloc(128, GFP_KERNEL);
		ssleep(5);
	}
	/* Should never get here */
	BUG_ON(1);
	return 0;
}

static int kmemleak_dbg_init(void)
{

	mem_alloc_kthread = kthread_create(memory_kthread_alloc, NULL, "mem_kthread");
	if (!IS_ERR(mem_alloc_kthread)) {
		wake_up_process(mem_alloc_kthread);
	}

	return 0;
}

static void kmemleak_dbg_exit(void)
{

	return 0;
}


module_init(kmemleak_dbg_init);

module_exit(kmemleak_dbg_exit);

MODULE_LICENSE("GPL");

2. 插入驅動後， echo scan > /sys/kernel/debug/kmemleak 

3.然後觀察，瀏覽內存泄漏情況：

   cat /sys/kernel/debug/kmemleak

unreferenced object 0xcbd86580 (size 128): //泄漏128字節
  comm "mem_kthread", pid 1676, jiffies 122870 (age 591.900s)
  hex dump (first 32 bytes):
    00 00 f2 cb 00 10 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 02 00 00 64 00 00 00 00  ...........d....
  backtrace://棧回溯，找到泄漏地址
    [<bf000018>] memory_kthread_alloc+0x18/0x3c [kmemleak]
    [<c00368cc>] kthread+0xdc/0xf0
    [<c000eb48>] ret_from_fork+0x14/0x2c
    [<ffffffff>] 0xffffffff