一、背景
在之前的博客 增加等IO状态的唤醒堆栈打印及缺页异常导致iowait分析-CSDN博客 里，我们进一步优化了D状态和等IO状态的事件的堆栈打印，补充了唤醒堆栈打印，也分析了一种比较典型的缺页异常filemap_fault导致的iowait的情况。
在这篇博客里，我们进一步补充缺页异常导致iowait这种场景下的信息，打印出是什么文件的filemap_fault，把文件的绝对路径打印出来。
在下面第二章里，我们给出源码和做源码的分析，在第三章里我们给出成果展示。
二、源码及源码分析
2.1 完整源码
#include <linux/module.h>
#include <linux/capability.h>
#include <linux/sched.h>
#include <linux/uaccess.h>
#include <linux/proc_fs.h>
#include <linux/ctype.h>
#include <linux/seq_file.h>
#include <linux/poll.h>
#include <linux/types.h>
#include <linux/ioctl.h>
#include <linux/errno.h>
#include <linux/stddef.h>
#include <linux/lockdep.h>
#include <linux/kthread.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/wait.h>
#include <linux/init.h>
#include <asm/atomic.h>
#include <trace/events/workqueue.h>
#include <linux/sched/clock.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/tracepoint.h>
#include <trace/events/osmonitor.h>
#include <trace/events/sched.h>
#include <trace/events/irq.h>
#include <trace/events/kmem.h>
#include <linux/ptrace.h>
#include <linux/uaccess.h>
#include <asm/processor.h>
#include <linux/sched/task_stack.h>
#include <linux/nmi.h>
#include <asm/apic.h>
#include <linux/version.h>
#include <linux/sched/mm.h>
#include <asm/irq_regs.h>
#include <linux/kallsyms.h>
#include <linux/kprobes.h>
#include <linux/stop_machine.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("zhaoxin");
MODULE_DESCRIPTION("Module for monitor D tasks.");
MODULE_VERSION("1.0");
#define IODELAY_TRACEPOINT_ENABLE
#define TEST_STACK_TRACE_ENTRIES 32
typedef unsigned int (*stack_trace_save_tsk_func)(struct task_struct *task,
unsigned long *store, unsigned int size,
unsigned int skipnr);
stack_trace_save_tsk_func _stack_trace_save_tsk;
typedef int (*get_cmdline_func)(struct task_struct *task, char *buffer, int buflen);
get_cmdline_func _get_cmdline_func;
#define TESTDIOMONITOR_SAMPLEDESC_SWDSTART "swDstart"
#define TESTDIOMONITOR_SAMPLEDESC_WADSTOP "waDstop"
#define TESTDIOMONITOR_SAMPLEDESC_SWDIOSTART "swDiostart"
#define TESTDIOMONITOR_SAMPLEDESC_WADIOSTOP "waDiostop"
#define TESTDIOMONITOR_SAMPLEDESC_DEXCEED "Dexceed"
#define TESTDIOMONITOR_SAMPLEDESC_DIOEXCEED "Dioexceed"
#define TESTDIOMONITOR_SAMPLEDESC_IOEXCEED "Ioexceed"
#define TESTDIOMONITOR_SIMPLE
#ifdef TESTDIOMONITOR_SIMPLE
#define TESTDIOMONITOR_SIMPLE_THRESHOLDNS 0ull//5000000ull
#endif
// 1ms
//#define TESTDIOMONITOR_DEXCEED_THRESHOLD 1000ull//1000000ull
struct uclamp_bucket {
unsigned long value : bits_per(SCHED_CAPACITY_SCALE);
unsigned long tasks : BITS_PER_LONG - bits_per(SCHED_CAPACITY_SCALE);
};
struct uclamp_rq {
unsigned int value;
struct uclamp_bucket bucket[UCLAMP_BUCKETS];
};
/* CFS-related fields in a runqueue */
struct cfs_rq {
struct load_weight load;
unsigned int nr_running;
unsigned int h_nr_running; /* SCHED_{NORMAL,BATCH,IDLE} */
unsigned int idle_nr_running; /* SCHED_IDLE */
unsigned int idle_h_nr_running; /* SCHED_IDLE */
u64 exec_clock;
u64 min_vruntime;
#ifdef CONFIG_SCHED_CORE
unsigned int forceidle_seq;
u64 min_vruntime_fi;
#endif
#ifndef CONFIG_64BIT
u64 min_vruntime_copy;
#endif
struct rb_root_cached tasks_timeline;
/*
* 'curr' points to currently running entity on this cfs_rq.
* It is set to NULL otherwise (i.e when none are currently running).
*/
struct sched_entity *curr;
struct sched_entity *next;
struct sched_entity *last;
struct sched_entity *skip;
#ifdef CONFIG_SCHED_DEBUG
unsigned int nr_spread_over;
#endif
#ifdef CONFIG_SMP
/*
* CFS load tracking
*/
struct sched_avg avg;
#ifndef CONFIG_64BIT
u64 last_update_time_copy;
#endif
struct {
raw_spinlock_t lock ____cacheline_aligned;
int nr;
unsigned long load_avg;
unsigned long util_avg;
unsigned long runnable_avg;
} removed;
#ifdef CONFIG_FAIR_GROUP_SCHED
unsigned long tg_load_avg_contrib;
long propagate;
long prop_runnable_sum;
/*
* h_load = weight * f(tg)
*
* Where f(tg) is the recursive weight fraction assigned to
* this group.
*/
unsigned long h_load;
u64 last_h_load_update;
struct sched_entity *h_load_next;
#endif /* CONFIG_FAIR_GROUP_SCHED */
#endif /* CONFIG_SMP */
#ifdef CONFIG_FAIR_GROUP_SCHED
struct rq *rq; /* CPU runqueue to which this cfs_rq is attached */
/*
* leaf cfs_rqs are those that hold tasks (lowest schedulable entity in
* a hierarchy). Non-leaf lrqs hold other higher schedulable entities
* (like users, containers etc.)
*
* leaf_cfs_rq_list ties together list of leaf cfs_rq's in a CPU.
* This list is used during load balance.
*/
int on_list;
struct list_head leaf_cfs_rq_list;
struct task_group *tg; /* group that "owns" this runqueue */
/* Locally cached copy of our task_group's idle value */
int idle;
#ifdef CONFIG_CFS_BANDWIDTH
int runtime_enabled;
s64 runtime_remaining;
u64 throttled_pelt_idle;
#ifndef CONFIG_64BIT
u64 throttled_pelt_idle_copy;
#endif
u64 throttled_clock;
u64 throttled_clock_pelt;
u64 throttled_clock_pelt_time;
int throttled;
int throttle_count;
struct list_head throttled_list;
#ifdef CONFIG_SMP
struct list_head throttled_csd_list;
#endif
#endif /* CONFIG_CFS_BANDWIDTH */
#endif /* CONFIG_FAIR_GROUP_SCHED */
};
struct rt_prio_array {
DECLARE_BITMAP(bitmap, MAX_RT_PRIO+1); /* include 1 bit for delimiter */
struct list_head queue[MAX_RT_PRIO];
};
/* Real-Time classes' related field in a runqueue: */
struct rt_rq {
struct rt_prio_array active;
unsigned int rt_nr_running;
unsigned int rr_nr_running;
#if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
struct {
int curr; /* highest queued rt task prio */
#ifdef CONFIG_SMP
int next; /* next highest */
#endif
} highest_prio;
#endif
#ifdef CONFIG_SMP
unsigned int rt_nr_migratory;
unsigned int rt_nr_total;
int overloaded;
struct plist_head pushable_tasks;
#endif /* CONFIG_SMP */
int rt_queued;
int rt_throttled;
u64 rt_time;
u64 rt_runtime;
/* Nests inside the rq lock: */
raw_spinlock_t rt_runtime_lock;
#ifdef CONFIG_RT_GROUP_SCHED
unsigned int rt_nr_boosted;
struct rq *rq;
struct task_group *tg;
#endif
};
/* Deadline class' related fields in a runqueue */
struct dl_rq {
/* runqueue is an rbtree, ordered by deadline */
struct rb_root_cached root;
unsigned int dl_nr_running;
#ifdef CONFIG_SMP
/*
* Deadline values of the currently executing and the
* earliest ready task on this rq. Caching these facilitates
* the decision whether or not a ready but not running task
* should migrate somewhere else.
*/
struct {
u64 curr;
u64 next;
} earliest_dl;
unsigned int dl_nr_migratory;
int overloaded;
/*
* Tasks on this rq that can be pushed away. They are kept in
* an rb-tree, ordered by tasks' deadlines, with caching
* of the leftmost (earliest deadline) element.
*/
struct rb_root_cached pushable_dl_tasks_root;
#else
struct dl_bw dl_bw;
#endif
/*
* "Active utilization" for this runqueue: increased when a
* task wakes up (becomes TASK_RUNNING) and decreased when a
* task blocks
*/
u64 running_bw;
/*
* Utilization of the tasks "assigned" to this runqueue (including
* the tasks that are in runqueue and the tasks that executed on this
* CPU and blocked). Increased when a task moves to this runqueue, and
* decreased when the task moves away (migrates, changes scheduling
* policy, or terminates).
* This is needed to compute the "inactive utilization" for the
* runqueue (inactive utilization = this_bw - running_bw).
*/
u64 this_bw;
u64 extra_bw;
/*
* Maximum available bandwidth for reclaiming by SCHED_FLAG_RECLAIM
* tasks of this rq. Used in calculation of reclaimable bandwidth(GRUB).
*/
u64 max_bw;
/*
* Inverse of the fraction of CPU utilization that can be reclaimed
* by the GRUB algorithm.
*/
u64 bw_ratio;
};
struct rq {
/* runqueue lock: */
raw_spinlock_t __lock;
/*
* nr_running and cpu_load should be in the same cacheline because
* remote CPUs use both these fields when doing load calculation.
*/
unsigned int nr_running;
#ifdef CONFIG_NUMA_BALANCING
unsigned int nr_numa_running;
unsigned int nr_preferred_running;
unsigned int numa_migrate_on;
#endif
#ifdef CONFIG_NO_HZ_COMMON
#ifdef CONFIG_SMP
unsigned long last_blocked_load_update_tick;
unsigned int has_blocked_load;
call_single_data_t nohz_csd;
#endif /* CONFIG_SMP */
unsigned int nohz_tick_stopped;
atomic_t nohz_flags;
#endif /* CONFIG_NO_HZ_COMMON */
#ifdef CONFIG_SMP
unsigned int ttwu_pending;
#endif
u64 nr_switches;
#ifdef CONFIG_UCLAMP_TASK
/* Utilization clamp values based on CPU's RUNNABLE tasks */
struct uclamp_rq uclamp[UCLAMP_CNT] ____cacheline_aligned;
unsigned int uclamp_flags;
#define UCLAMP_FLAG_IDLE 0x01
#endif
struct cfs_rq cfs;
struct rt_rq rt;
struct dl_rq dl;
#ifdef CONFIG_FAIR_GROUP_SCHED
/* list of leaf cfs_rq on this CPU: */
struct list_head leaf_cfs_rq_list;
struct list_head *tmp_alone_branch;
#endif /* CONFIG_FAIR_GROUP_SCHED */
/*
* This is part of a global counter where only the total sum
* over all CPUs matters. A task can increase this counter on
* one CPU and if it got migrated afterwards it may decrease
* it on another CPU. Always updated under the runqueue lock:
*/
unsigned int nr_uninterruptible;
struct task_struct __rcu *curr;
struct task_struct *idle;
struct task_struct *stop;
unsigned long next_balance;
struct mm_struct *prev_mm;
unsigned int clock_update_flags;
u64 clock;
/* Ensure that all clocks are in the same cache line */
u64 clock_task ____cacheline_aligned;
u64 clock_pelt;
unsigned long lost_idle_time;
atomic_t nr_iowait;
#ifdef CONFIG_SCHED_DEBUG
u64 last_seen_need_resched_ns;
int ticks_without_resched;
#endif
#ifdef CONFIG_MEMBARRIER
int membarrier_state;
#endif
#ifdef CONFIG_SMP
struct root_domain *rd;
struct sched_domain __rcu *sd;
unsigned long cpu_capacity;
unsigned long cpu_capacity_orig;
struct callback_head *balance_callback;
unsigned char nohz_idle_balance;
unsigned char idle_balance;
unsigned long misfit_task_load;
/* For active balancing */
int active_balance;
int push_cpu;
struct cpu_stop_work active_balance_work;
/* CPU of this runqueue: */
int cpu;
int online;
struct list_head cfs_tasks;
struct sched_avg avg_rt;
struct sched_avg avg_dl;
#ifdef CONFIG_HAVE_SCHED_AVG_IRQ
struct sched_avg avg_irq;
#endif
#ifdef CONFIG_SCHED_THERMAL_PRESSURE
struct sched_avg avg_thermal;
#endif
u64 idle_stamp;
u64 avg_idle;
unsigned long wake_stamp;
u64 wake_avg_idle;
/* This is used to determine avg_idle's max value */
u64 max_idle_balance_cost;
#ifdef CONFIG_HOTPLUG_CPU
struct rcuwait hotplug_wait;
#endif
#endif /* CONFIG_SMP */
#ifdef CONFIG_IRQ_TIME_ACCOUNTING
u64 prev_irq_time;
#endif
#ifdef CONFIG_PARAVIRT
u64 prev_steal_time;
#endif
#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
u64 prev_steal_time_rq;
#endif
/* calc_load related fields */
unsigned long calc_load_update;
long calc_load_active;
#ifdef CONFIG_SCHED_HRTICK
#ifdef CONFIG_SMP
call_single_data_t hrtick_csd;
#endif
struct hrtimer hrtick_timer;
ktime_t hrtick_time;
#endif
#ifdef CONFIG_SCHEDSTATS
/* latency stats */
struct sched_info rq_sched_info;
unsigned long long rq_cpu_time;
/* could above be rq->cfs_rq.exec_clock + rq->rt_rq.rt_runtime ? */
/* sys_sched_yield() stats */
unsigned int yld_count;
/* schedule() stats */
unsigned int sched_count;
unsigned int sched_goidle;
/* try_to_wake_up() stats */
unsigned int ttwu_count;
unsigned int ttwu_local;
#endif
#ifdef CONFIG_CPU_IDLE
/* Must be inspected within a rcu lock section */
struct cpuidle_state *idle_state;
#endif
#ifdef CONFIG_SMP
unsigned int nr_pinned;
#endif
unsigned int push_busy;
struct cpu_stop_work push_work;
#ifdef CONFIG_SCHED_CORE
/* per rq */
struct rq *core;
struct task_struct *core_pick;
unsigned int core_enabled;
unsigned int core_sched_seq;
struct rb_root core_tree;
/* shared state -- careful with sched_core_cpu_deactivate() */
unsigned int core_task_seq;
unsigned int core_pick_seq;
unsigned long core_cookie;
unsigned int core_forceidle_count;
unsigned int core_forceidle_seq;
unsigned int core_forceidle_occupation;
u64 core_forceidle_start;
#endif
};
// runqueues (not export symbol)
struct rq* _prq = NULL;
struct rq* my_cpu_rq(int i_cpu)
{
return per_cpu_ptr(_prq, i_cpu);
}
u64 my_rq_clock_task(void)
{
struct rq* prq = my_cpu_rq(smp_processor_id());
return prq->clock_task;
}
#define TESTDIOMONITOR_FILE_MAXLEN 1024
typedef struct testdiomonitor_sample {
struct timespec64 time;
int cpu;
int pid;
int tgid;
int ppid;
char comm[TASK_COMM_LEN];
char ppidcomm[TASK_COMM_LEN];
// 0 or 1
int bin_iowait;
/*
* "swDstart" // 在sched_switch里
* "waDstop" // 在sched_waking里
* "swDiostart" // 在sched_switch里
* "waDiostop" // 在sched_waking里
* "Dexceed" // 超出阈值，非iowait
* "Dioexceed" // 超出阈值，iowait
*/
const char* desc;
u64 dtimens; // 纳秒单位，D状态持续的时间
u64 iowaittimens; // 纳秒单位，等待io的时间
int stackn;
void* parray_stack[TEST_STACK_TRACE_ENTRIES];
int wakercpu;
int wakerpid;
int wakertgid;
int wakerppid;
char wakercomm[TASK_COMM_LEN];
char wakerppidcomm[TASK_COMM_LEN];
int wakerstackn;
void* parray_wakerstack[TEST_STACK_TRACE_ENTRIES];
char filepath[TESTDIOMONITOR_FILE_MAXLEN];
u32 writedone; // 0 or 1
} testdiomonitor_sample;
#define TESTDIOMONITOR_SAMPLE_RINGBUFF_MAXCOUNT 8192
typedef struct testdiomonitor_sample_ringbuff {
testdiomonitor_sample* parray_sample;
volatile u64 wp; // Index is wp & (TESTDIOMONITOR_SAMPLE_RINGBUFF_MAXCOUNT - 1).
volatile u64 rp; // Index is rp & (TESTDIOMONITOR_SAMPLE_RINGBUFF_MAXCOUNT - 1).
u32 skipcount; // 0 means no skip any abnormal event
} testdiomonitor_sample_ringbuff;
#define TESTDIOMONITOR_LINEBUFF 1024
typedef struct testdiomonitor_env {
struct file* file;
char file_linebuff[TESTDIOMONITOR_LINEBUFF];
int headoffset;
loff_t file_pos;
testdiomonitor_sample_ringbuff ringbuff;
} testdiomonitor_env;
static testdiomonitor_env _env;
static struct delayed_work work_write_file;
static struct workqueue_struct *wq_write_file;
#define FILENAME "test_new.txt"
void init_file(void)
{
_env.file = filp_open(FILENAME, O_WRONLY | O_CREAT | O_TRUNC, 0644);
if (IS_ERR(_env.file)) {
_env.file = NULL;
}
}
void exit_file(void)
{
if (_env.file) {
filp_close(_env.file, NULL);
}
}
void testdiomonitor_write_file(char* i_pchar, int i_size)
{
if (_env.file) {
kernel_write(_env.file, i_pchar, i_size, &_env.file_pos);
}
}
void testdiomonitor_write_file_emptyline(void)
{
testdiomonitor_write_file("\n", strlen("\n"));
}
void testdiomonitor_file_oneline(const char* i_format, ...)
{
char* pcontent = &_env.file_linebuff[_env.headoffset];
va_list args;
va_start(args, i_format);
vsnprintf(pcontent, TESTDIOMONITOR_LINEBUFF - _env.headoffset, i_format, args);
va_end(args);
testdiomonitor_write_file(_env.file_linebuff, strlen(_env.file_linebuff));
}
void testdiomonitor_replace_null_with_space(char *str, int n) {
for (int i = 0; i < n - 1; i++) {
if (str[i] == '\0') {
str[i] = ' ';
}
}
}
void testdiomonitor_set_cmdline(char* i_pbuff, int i_buffsize, struct task_struct* i_ptask)
{
int ret = _get_cmdline_func(i_ptask, i_pbuff, i_buffsize);
if (ret <= 0) {
i_pbuff[0] = '\0';
return;
}
testdiomonitor_replace_null_with_space(i_pbuff, ret);
i_pbuff[ret - 1] = '\0';
}
void testdiomonitor_checkget_parentinfo_and_cmdline(testdiomonitor_sample* io_psample, struct task_struct* i_ptask)
{
struct task_struct* parent;
rcu_read_lock();
parent = rcu_dereference(i_ptask->real_parent);
io_psample->ppid = parent->pid;
strlcpy(io_psample->ppidcomm, parent->comm, TASK_COMM_LEN);
rcu_read_unlock();
}
void testdiomonitor_checkget_parentinfo_and_cmdline_waker(testdiomonitor_sample* io_psample, struct task_struct* i_ptask)
{
struct task_struct* parent;
rcu_read_lock();
parent = rcu_dereference(i_ptask->real_parent);
io_psample->wakerppid = parent->pid;
strlcpy(io_psample->wakerppidcomm, parent->comm, TASK_COMM_LEN);
rcu_read_unlock();
}
#define TESTDIOMONITOR_COMMANDLINE_MAX 128
static void write_file(struct work_struct *w)
{
ssize_t ret;
u32 index;
testdiomonitor_sample* psample;
struct tm t;
char timestr[64];
char exceedstr[64];
char temp_commandline[TESTDIOMONITOR_COMMANDLINE_MAX];
struct pid* pid_struct;
struct task_struct* ptask;
int stacki;
while (_env.ringbuff.rp != _env.ringbuff.wp) {
index = (_env.ringbuff.rp & (TESTDIOMONITOR_SAMPLE_RINGBUFF_MAXCOUNT - 1));
psample = &_env.ringbuff.parray_sample[index];
if (psample->writedone != 1) {
break;
}
testdiomonitor_write_file_emptyline();
_env.headoffset = sprintf(_env.file_linebuff, "[%llu][%s] ", _env.ringbuff.rp, psample->desc);
time64_to_tm(psample->time.tv_sec + 8 * 60 * 60, 0, &t);
snprintf(timestr, 64, "%04ld-%02d-%02d-%02d_%02d_%02d.%09ld",
1900 + t.tm_year, t.tm_mon + 1, t.tm_mday, t.tm_hour, t.tm_min, t.tm_sec, psample->time.tv_nsec);
if (psample->desc == TESTDIOMONITOR_SAMPLEDESC_DEXCEED) {
snprintf(exceedstr, 64, "dtimens[%llu]", psample->dtimens);
}
else if (psample->desc == TESTDIOMONITOR_SAMPLEDESC_DIOEXCEED) {
snprintf(exceedstr, 64, "iowaittimens[%llu]", psample->iowaittimens);
}
else if (psample->desc == TESTDIOMONITOR_SAMPLEDESC_IOEXCEED) {
snprintf(exceedstr, 64, "delayacct_iowaittimens[%llu]", psample->iowaittimens);
}
else {
exceedstr[0] = '\0';
}
if (psample->desc == TESTDIOMONITOR_SAMPLEDESC_DIOEXCEED) {
testdiomonitor_file_oneline("begin...time[%s]wakercpu[%d]desc[%s]%s\n",
timestr, psample->wakercpu, psample->desc, "wakerDioexceed");
testdiomonitor_file_oneline("wakertgid[%d]wakerpid[%d]wakercomm[%s]wakerppid[%d]wakerppidcomm[%s]\n",
psample->wakertgid, psample->wakerpid, psample->wakercomm, psample->wakerppid, psample->wakerppidcomm);
pid_struct = find_get_pid(psample->wakerpid);
if (pid_struct) {
ptask = get_pid_task(pid_struct, PIDTYPE_PID);
if (ptask) {
testdiomonitor_set_cmdline(temp_commandline, TESTDIOMONITOR_COMMANDLINE_MAX, ptask);
put_task_struct(ptask);
}
else {
temp_commandline[0] = '\0';
}
put_pid(pid_struct);
}
else {
temp_commandline[0] = '\0';
}
testdiomonitor_file_oneline("wakercommandline[%s]\n", temp_commandline);
pid_struct = find_get_pid(psample->wakerppid);
if (pid_struct) {
ptask = get_pid_task(pid_struct, PIDTYPE_PID);
if (ptask) {
testdiomonitor_set_cmdline(temp_commandline, TESTDIOMONITOR_COMMANDLINE_MAX, ptask);
put_task_struct(ptask);
}
else {
temp_commandline[0] = '\0';
}
put_pid(pid_struct);
}
else {
temp_commandline[0] = '\0';
}
testdiomonitor_file_oneline("wakerppid_commandline[%s]\n", temp_commandline);
testdiomonitor_file_oneline("stack[%d]:\n", psample->wakerstackn);
for (stacki = 0; stacki < psample->wakerstackn; stacki++) {
testdiomonitor_file_oneline("%*c%pS\n", 5, ' ', (void *)psample->parray_wakerstack[stacki]);
}
testdiomonitor_file_oneline("cpu[%d]desc[%s]%s\n",
psample->cpu, psample->desc, exceedstr);
}
else {
testdiomonitor_file_oneline("begin...time[%s]cpu[%d]desc[%s]%s\n",
timestr, psample->cpu, psample->desc, exceedstr);
}
testdiomonitor_file_oneline("tgid[%d]pid[%d]comm[%s]ppid[%d]ppidcomm[%s]\n",
psample->tgid, psample->pid, psample->ppidcomm, psample->ppid, psample->ppidcomm);
pid_struct = find_get_pid(psample->pid);
if (pid_struct) {
ptask = get_pid_task(pid_struct, PIDTYPE_PID);
if (ptask) {
testdiomonitor_set_cmdline(temp_commandline, TESTDIOMONITOR_COMMANDLINE_MAX, ptask);
put_task_struct(ptask);
}
else {
temp_commandline[0] = '\0';
}
put_pid(pid_struct);
}
else {
temp_commandline[0] = '\0';
}
testdiomonitor_file_oneline("commandline[%s]\n", temp_commandline);
pid_struct = find_get_pid(psample->ppid);
if (pid_struct) {
ptask = get_pid_task(pid_struct, PIDTYPE_PID);
if (ptask) {
testdiomonitor_set_cmdline(temp_commandline, TESTDIOMONITOR_COMMANDLINE_MAX, ptask);
put_task_struct(ptask);
}
else {
temp_commandline[0] = '\0';
}
put_pid(pid_struct);
}
else {
temp_commandline[0] = '\0';
}
testdiomonitor_file_oneline("ppid_commandline[%s]\n", temp_commandline);
testdiomonitor_file_oneline("filepath[%s]\n", psample->filepath);
testdiomonitor_file_oneline("stack[%d]:\n", psample->stackn);
for (stacki = 0; stacki < psample->stackn; stacki++) {
testdiomonitor_file_oneline("%*c%pS\n", 5, ' ', (void *)psample->parray_stack[stacki]);
}
testdiomonitor_write_file_emptyline();
psample->writedone = 0;
_env.ringbuff.rp ++;
}
queue_delayed_work_on(nr_cpu_ids - 1, wq_write_file,
&work_write_file, 1);
}
static void init_write_file(void)
{
init_file();
wq_write_file = alloc_workqueue("testdiomonitor_write_file", WQ_MEM_RECLAIM, 0);
INIT_DELAYED_WORK(&work_write_file, write_file);
queue_delayed_work_on(nr_cpu_ids - 1, wq_write_file,
&work_write_file, 3);
}
static void exit_write_file(void)
{
cancel_delayed_work_sync(&work_write_file);
destroy_workqueue(wq_write_file);
exit_file();
}
void init_testdiomonitor_sample_ringbuff(void)
{
testdiomonitor_sample* psample;
_env.ringbuff.parray_sample = kvzalloc(sizeof(testdiomonitor_sample) * TESTDIOMONITOR_SAMPLE_RINGBUFF_MAXCOUNT, GFP_KERNEL);
}
void exit_testdiomonitor_sample_ringbuff(void)
{
kvfree(_env.ringbuff.parray_sample);
}
testdiomonitor_sample* testdiomonitor_get_psample(void)
{
u64 windex_raw, windex_raw_old;
u32 windex;
while (1) {
windex_raw = _env.ringbuff.wp;
if (windex_raw - _env.ringbuff.rp >= (u64)(TESTDIOMONITOR_SAMPLE_RINGBUFF_MAXCOUNT)) {
_env.ringbuff.skipcount ++;
return NULL;
}
// atomic_cmpxchg return old value
windex_raw_old = atomic64_cmpxchg((atomic64_t*)&_env.ringbuff.wp,
windex_raw, windex_raw + 1);
if (windex_raw_old == windex_raw) {
break;
}
}
windex = (u32)(windex_raw & (u64)(TESTDIOMONITOR_SAMPLE_RINGBUFF_MAXCOUNT - 1));
return &_env.ringbuff.parray_sample[windex];
}
static u64 _magic_number = 0xABCDEFull;
void* _dl_sched_class = NULL;
int get_file_dir_by_folio(struct folio *i_fo, char* i_path, int i_len);
void testdiomonitor_add_sample(const char* i_desc, struct task_struct* i_task, u64 i_timens)
{
testdiomonitor_sample* psample = testdiomonitor_get_psample();
if (!psample) {
return;
}
ktime_get_real_ts64(&psample->time);
psample->cpu = task_cpu(i_task);
psample->pid = i_task->pid;
psample->tgid = i_task->tgid;
strlcpy(psample->comm, i_task->comm, TASK_COMM_LEN);
testdiomonitor_checkget_parentinfo_and_cmdline(psample, i_task);
psample->bin_iowait = i_task->in_iowait;
psample->desc = i_desc;
if (i_desc == TESTDIOMONITOR_SAMPLEDESC_DEXCEED) {
psample->dtimens = i_timens;
}
else if (i_desc == TESTDIOMONITOR_SAMPLEDESC_DIOEXCEED || i_desc == TESTDIOMONITOR_SAMPLEDESC_IOEXCEED) {
psample->iowaittimens = i_timens;
}
psample->stackn = _stack_trace_save_tsk(i_task, (unsigned long*)psample->parray_stack, TEST_STACK_TRACE_ENTRIES, 0);
if (i_desc == TESTDIOMONITOR_SAMPLEDESC_DIOEXCEED) {
psample->wakercpu = smp_processor_id();
psample->wakerpid = current->pid;
psample->wakertgid = current->tgid;
strlcpy(psample->wakercomm, current->comm, TASK_COMM_LEN);
testdiomonitor_checkget_parentinfo_and_cmdline_waker(psample, current);
psample->wakerstackn = _stack_trace_save_tsk(current, (unsigned long*)psample->parray_wakerstack, TEST_STACK_TRACE_ENTRIES, 0);
psample->filepath[0] = '\0';
if (i_task->sched_class != &_dl_sched_class) {
if (i_task->dl.dl_runtime == _magic_number) {
//if (sched_clock() - i_task->dl.dl_deadline >= TESTDIOMONITOR_SIMPLE_THRESHOLDNS)
{
//printk("__folio_lock_killable wait %llu ns\n", sched_clock() - current->dl.dl_deadline);
//dump_stack();
if (get_file_dir_by_folio((struct folio*)i_task->dl.dl_period, psample->filepath, TESTDIOMONITOR_FILE_MAXLEN) < 0) {
//printk("get_file_dir_by_folio fail!\n");
}
}
current->dl.dl_runtime = 0;
}
}
}
psample->writedone = 1;
}
static void cb_sched_switch(void *i_data, bool i_preempt,
struct task_struct *i_prev,
struct task_struct *i_next,
unsigned int i_prev_state)
{
#ifndef TESTDIOMONITOR_SIMPLE
void* parray_stack[TEST_STACK_TRACE_ENTRIES];
int num_stack;
int stacki;
if (i_prev_state == TASK_UNINTERRUPTIBLE) {
if (i_prev->in_iowait) {
testdiomonitor_add_sample(TESTDIOMONITOR_SAMPLEDESC_SWDIOSTART, i_prev, 0);
}
else {
testdiomonitor_add_sample(TESTDIOMONITOR_SAMPLEDESC_SWDSTART, i_prev, 0);
}
}
else if (i_prev->in_iowait) {
testdiomonitor_add_sample(TESTDIOMONITOR_SAMPLEDESC_SWDIOSTART, i_prev, 0);
}
#endif
}
const char* getstatstr_bystate(u32 i_state) {
switch (i_state) {
case TASK_RUNNING:
return "TASK_RUNNING";
case TASK_INTERRUPTIBLE:
return "TASK_INTERRUPTIBLE";
case TASK_UNINTERRUPTIBLE:
return "TASK_UNINTERRUPTIBLE";
default:
return "other";
}
}
static void cb_sched_waking(void *i_data, struct task_struct *i_p) {
if (i_p->__state == TASK_UNINTERRUPTIBLE) {
//u64 currns = my_rq_clock_task();
struct rq* prq = my_cpu_rq(task_cpu(i_p));
u64 currns = prq->clock_task;
u64 local_c = local_clock();
int cpuid = smp_processor_id();
if (i_p->in_iowait) {
#ifndef TESTDIOMONITOR_SIMPLE
testdiomonitor_add_sample(TESTDIOMONITOR_SAMPLEDESC_WADIOSTOP, i_p, 0);
#endif
#ifdef TESTDIOMONITOR_SIMPLE
if (currns - i_p->se.exec_start >= TESTDIOMONITOR_SIMPLE_THRESHOLDNS)
#endif
testdiomonitor_add_sample(TESTDIOMONITOR_SAMPLEDESC_DIOEXCEED, i_p, currns - i_p->se.exec_start);
#ifndef TESTDIOMONITOR_SIMPLE
if (i_p->se.exec_start > currns)
{
//if (task_cpu(i_p) == cpuid)
{
printk("comm[%s]pid[%d]exec_start[%llu]currns[%llu]local_clock[%llu]last_cpu[%d]cpuid[%d]\n",
i_p->comm, i_p->pid, i_p->se.exec_start, currns, local_c, task_cpu(i_p), cpuid);
}
}
// if (printk_ratelimit()) {
// printk("waking dump_stack[D]:\n");
// dump_stack();
// }
#endif
}
#ifndef TESTDIOMONITOR_SIMPLE
else {
testdiomonitor_add_sample(TESTDIOMONITOR_SAMPLEDESC_WADSTOP, i_p, 0);
testdiomonitor_add_sample(TESTDIOMONITOR_SAMPLEDESC_DEXCEED, i_p, my_rq_clock_task() - i_p->se.exec_start);
if (i_p->se.exec_start > currns)
{
//if (task_cpu(i_p) == cpuid)
{
printk("comm[%s]pid[%d]exec_start[%llu]currns[%llu]local_clock[%llu]last_cpu[%d]cpuid[%d]\n",
i_p->comm, i_p->pid, i_p->se.exec_start, currns, local_c, task_cpu(i_p), cpuid);
}
}
}
#endif
}
else if (i_p->in_iowait) {
struct rq* prq = my_cpu_rq(task_cpu(i_p));
u64 currns = prq->clock_task;
u64 local_c = local_clock();
int cpuid = smp_processor_id();
//if (printk_ratelimit())
// {
// printk("i_p->__state=[%u][%s]\n", i_p->__state, getstatstr_bystate(i_p->__state));
// printk("waking dump_stack[K]:\n");
// dump_stack();
// }
#ifndef TESTDIOMONITOR_SIMPLE
testdiomonitor_add_sample(TESTDIOMONITOR_SAMPLEDESC_WADIOSTOP, i_p, 0);
#endif
#ifdef TESTDIOMONITOR_SIMPLE
if (currns - i_p->se.exec_start >= TESTDIOMONITOR_SIMPLE_THRESHOLDNS)
#endif
testdiomonitor_add_sample(TESTDIOMONITOR_SAMPLEDESC_DIOEXCEED, i_p, currns - i_p->se.exec_start);
}
}
static void cb_iodelay_account(void *i_data, struct task_struct *i_curr,
unsigned long long i_delta)
{
#ifdef TESTDIOMONITOR_SIMPLE
if (i_delta >= TESTDIOMONITOR_SIMPLE_THRESHOLDNS)
#endif
testdiomonitor_add_sample(TESTDIOMONITOR_SAMPLEDESC_IOEXCEED, i_curr, i_delta);
}
struct kern_tracepoint {
void *callback;
struct tracepoint *ptr;
bool bregister;
};
static void clear_kern_tracepoint(struct kern_tracepoint *tp)
{
if (tp->bregister) {
tracepoint_probe_unregister(tp->ptr, tp->callback, NULL);
}
}
#define INIT_KERN_TRACEPOINT(tracepoint_name) \
static struct kern_tracepoint mykern_##tracepoint_name = {.callback = NULL, .ptr = NULL, .bregister = false};
#define TRACEPOINT_CHECK_AND_SET(tracepoint_name) \
static void tracepoint_name##_tracepoint_check_and_set(struct tracepoint *tp, void *priv) \
{ \
if (!strcmp(#tracepoint_name, tp->name)) \
{ \
((struct kern_tracepoint *)priv)->ptr = tp; \
return; \
} \
}
INIT_KERN_TRACEPOINT(sched_switch)
TRACEPOINT_CHECK_AND_SET(sched_switch)
INIT_KERN_TRACEPOINT(sched_waking)
TRACEPOINT_CHECK_AND_SET(sched_waking)
#ifdef IODELAY_TRACEPOINT_ENABLE
INIT_KERN_TRACEPOINT(iodelay_account)
TRACEPOINT_CHECK_AND_SET(iodelay_account)
#endif
typedef unsigned long (*kallsyms_lookup_name_func)(const char *name);
kallsyms_lookup_name_func _kallsyms_lookup_name_func;
void* get_func_by_symbol_name_kallsyms_lookup_name(void)
{
int ret;
void* pfunc = NULL;
struct kprobe kp;
memset(&kp, 0, sizeof(kp));
kp.symbol_name = "kallsyms_lookup_name";
kp.pre_handler = NULL;
kp.addr = NULL; // 作为强调，提示使用symbol_name
ret = register_kprobe(&kp);
if (ret < 0) {
printk("register_kprobe fail!\n");
return NULL;
}
printk("register_kprobe succeed!\n");
pfunc = (void*)kp.addr;
unregister_kprobe(&kp);
return pfunc;
}
void* get_func_by_symbol_name(const char* i_symbol)
{
if (_kallsyms_lookup_name_func == NULL) {
return NULL;
}
return _kallsyms_lookup_name_func(i_symbol);
}
enum behavior {
EXCLUSIVE, /* Hold ref to page and take the bit when woken, like
* __folio_lock() waiting on then setting PG_locked.
*/
SHARED, /* Hold ref to page and check the bit when woken, like
* folio_wait_writeback() waiting on PG_writeback.
*/
DROP, /* Drop ref to page before wait, no check when woken,
* like folio_put_wait_locked() on PG_locked.
*/
};
int kprobecb_folio_lock_killable_pre(struct kprobe* i_k, struct pt_regs* i_p)
{
if (current->sched_class != &_dl_sched_class) {
struct folio *fo = (struct folio*) i_p->di;
int bit_nr = (int)i_p->si;
int state = (int)i_p->dx;
enum behavior beh = (enum behavior)i_p->cx;
if (bit_nr != PG_locked
|| state != TASK_KILLABLE
|| beh != EXCLUSIVE) {
return 0;
}
current->dl.dl_runtime = _magic_number;
current->dl.dl_deadline = sched_clock();
current->dl.dl_period = (u64)fo;
}
return 0;
}
int getfullpath(struct inode *inode,char* i_buffer,int i_len)
{
struct dentry *dentry;
//printk("inode = %ld\n", inode->i_ino);
//spin_lock(&inode->i_lock);
hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) {
char *buffer, *path;
buffer = (char *)__get_free_page(GFP_KERNEL);
if (!buffer)
return -ENOMEM;
path = dentry_path_raw(dentry, buffer, PAGE_SIZE);
if (IS_ERR(path)){
continue;
}
strlcpy(i_buffer, path, i_len);
//printk("dentry name = %s , path = %s", dentry->d_name.name, path);
free_page((unsigned long)buffer);
}
//spin_unlock(&inode->i_lock);
return 0;
}
int get_file_dir_by_folio(struct folio *i_fo, char* i_path, int i_len)
{
if (i_fo->mapping) {
struct inode *inode = i_fo->mapping->host;
if (inode) {
// struct dentry *dentry = inode->i_dentry;
// if (!dentry) {
// return -1;
// }
{
//char path_buf[256];
int ret = 0;
if ((ret = getfullpath(inode, i_path, i_len)) < 0) {
return ret;
}
// struct path path;
// //dentry_lock(dentry);
// path.dentry = dentry;
// path.mnt = dget(dentry->d_sb->s_root);
// if (dentry_path_raw(dentry, path_buf, sizeof(path_buf)) >= 0) {
// pr_info("File path: %s\n", path_buf);
// }
//dentry_unlock(dentry);
}
return 0;
}
}
return -1;
}
struct kprobe _kp1;
void kprobecb_folio_lock_killable_post(struct kprobe *p, struct pt_regs *regs,
unsigned long flags)
{
// if (current->sched_class != &_dl_sched_class) {
// if (current->dl.dl_runtime == _magic_number) {
// if (sched_clock() - current->dl.dl_deadline >= TESTDIOMONITOR_SIMPLE_THRESHOLDNS) {
// //printk("__folio_lock_killable wait %llu ns\n", sched_clock() - current->dl.dl_deadline);
// //dump_stack();
// if (get_file_dir_by_folio((struct folio*)current->dl.dl_period) < 0) {
// printk("get_file_dir_by_folio fail!\n");
// }
// }
// current->dl.dl_runtime = 0;
// }
// }
}
int kprobe_register_func_folio_lock_killable(void)
{
int ret;
memset(&_kp1, 0, sizeof(_kp1));
_kp1.symbol_name = "folio_wait_bit_common";
_kp1.pre_handler = kprobecb_folio_lock_killable_pre;
_kp1.post_handler = kprobecb_folio_lock_killable_post;
ret = register_kprobe(&_kp1);
if (ret < 0) {
printk("register_kprobe fail!\n");
return -1;
}
printk("register_kprobe success!\n");
return 0;
}
void kprobe_unregister_func_folio_lock_killable(void)
{
unregister_kprobe(&_kp1);
}
static int __init testdiomonitor_init(void)
{
//printk("offset of mmap_lock in mm_struct [%d]\n", offsetof(struct mm_struct, mmap_lock));
_kallsyms_lookup_name_func = get_func_by_symbol_name_kallsyms_lookup_name();
_dl_sched_class = (void*)_kallsyms_lookup_name_func("dl_sched_class");
if (_dl_sched_class == NULL) {
printk(KERN_ERR "get_func_by_symbol_name _dl_sched_class failed!\n");
return -1;
}
_prq = get_func_by_symbol_name("runqueues");
if (_prq == NULL) {
printk(KERN_ERR "get_func_by_symbol_name runqueues failed!\n");
return -1;
}
init_testdiomonitor_sample_ringbuff();
init_write_file();
_stack_trace_save_tsk = get_func_by_symbol_name("stack_trace_save_tsk");
if (_stack_trace_save_tsk == NULL) {
printk(KERN_ERR "get_func_by_symbol_name stack_trace_save_tsk failed!\n");
return -1;
}
_get_cmdline_func = get_func_by_symbol_name("get_cmdline");
if (_get_cmdline_func == NULL) {
printk(KERN_ERR "get_func_by_symbol_name get_cmdline failed!\n");
return -1;
}
mykern_sched_switch.callback = cb_sched_switch;
for_each_kernel_tracepoint(sched_switch_tracepoint_check_and_set, &mykern_sched_switch);
if (!mykern_sched_switch.ptr) {
printk(KERN_ERR "mykern_sched_switch register failed!\n");
return -1;
}
else {
printk(KERN_INFO "mykern_sched_switch register succeeded!\n");
}
tracepoint_probe_register(mykern_sched_switch.ptr, mykern_sched_switch.callback, NULL);
mykern_sched_switch.bregister = 1;
mykern_sched_waking.callback = cb_sched_waking;
for_each_kernel_tracepoint(sched_waking_tracepoint_check_and_set, &mykern_sched_waking);
if (!mykern_sched_waking.ptr) {
printk(KERN_ERR "mykern_sched_waking register failed!\n");
return -1;
}
else {
printk(KERN_INFO "mykern_sched_waking register succeeded!\n");
}
tracepoint_probe_register(mykern_sched_waking.ptr, mykern_sched_waking.callback, NULL);
mykern_sched_waking.bregister = 1;
#ifdef IODELAY_TRACEPOINT_ENABLE
mykern_iodelay_account.callback = cb_iodelay_account;
for_each_kernel_tracepoint(iodelay_account_tracepoint_check_and_set, &mykern_iodelay_account);
if (!mykern_iodelay_account.ptr) {
printk(KERN_ERR "mykern_iodelay_account register failed!\n");
return -1;
}
else {
printk(KERN_INFO "mykern_iodelay_account register succeeded!\n");
}
tracepoint_probe_register(mykern_iodelay_account.ptr, mykern_iodelay_account.callback, NULL);
mykern_iodelay_account.bregister = 1;
#endif
kprobe_register_func_folio_lock_killable();
return 0;
}
static void __exit testdiomonitor_exit(void)
{
kprobe_unregister_func_folio_lock_killable();
clear_kern_tracepoint(&mykern_sched_switch);
clear_kern_tracepoint(&mykern_sched_waking);
#ifdef IODELAY_TRACEPOINT_ENABLE
clear_kern_tracepoint(&mykern_iodelay_account);
#endif
tracepoint_synchronize_unregister();
exit_write_file();
exit_testdiomonitor_sample_ringbuff();
}
module_init(testdiomonitor_init);
module_exit(testdiomonitor_exit);
2.2 源码分析
2.2.1 增加filepath这个缺页异常对应的文件绝对路径的变量及主要逻辑
添加了filepath这个采样信息：
在打印时增加了filepath的打印：
在TESTDIOMONITOR_SAMPLEDESC_DIOEXCEED类型时，设置filepath的值：
设置的方法借用了deadline调度器才会用到的几个task_struct里的变量，而deadline调度器一般是用不上的，除非特别指定使用deadline调度器的任务才会用上，关于deadline调度器的更多细节和实验在之前的博客 不修改内核镜像的情况下，使用内核模块实现“及时”的调度时间片超时事件上报-CSDN博客 的 2.1.1 一节里有介绍。
这里的逻辑里我们使用了deadline调度器的这几个变量来保存着相关缺页异常的页的结构体的地址（保存在dl.dl_period里），还有一个辅助用的变量，来记一个魔鬼数字magic number，记到dl_runtime里，来确定是我们的逻辑修改的这个变量，在用完这个folio的指针后，再清除这个magic number。另外，肯定需要确定是否这个任务的调度类是否是deadline调度类。
在下面 2.2.2 一节里我们讲怎么通过内核模块的逻辑捞到这个folio指针，然后在 2.2.3 一节里，我们展开介绍上图里的get_file_dir_by_folio函数的实现，是如何通过这个folio指针找到对应文件的绝对路径的。
2.2.2 通过内核模块逻辑捞到这个folio指针
我们是通过kprobe来捕获folio_wait_bit_common执行前的时候来拿到传入的参数：
folio_wait_bit_common函数的第一个参数就是folio的指针：
为什么用folio_wait_bit_common函数而不用在之前的博客 增加等IO状态的唤醒堆栈打印及缺页异常导致iowait分析-CSDN博客 里的 3.2 一节里分析的必然调用到的__folio_lock_killable函数，是因为__folio_lock_killable函数虽然被export symbol了出来，但是它并不是在每次被调用时都走函数调用的形式，在我们抓到的filemap_fault这个调用链场景下，__folio_lock_killable函数是被inline调用的。所以，我们得在stack里看到的folio_wait_bit_common函数里来加kprobe。
我们在kprobe的pre_handler的回调函数里，如果非deadline调度类场景，就执行记录folio指针的逻辑，在记录folio指针前要进行一定的判断，根据获取到folio_wait_bit_common函数传入的四个参数，如下图：
根据这四个参数的情况，筛选出是filemap_fault必经的__folio_lock_killable的场景，如下图：
判断对的话，再执行记录动作：
记录了folio指针到dl.dl_period里，另外，还写了一个magic number：
2.2.3 通过folio指针找到对应文件的绝对路径
在代码里，我们如下图的get_file_dir_by_folio函数实现了“通过folio指针找到对应文件的绝对路径”的功能：
调用的是getfullpath如下图：
如上图框出的两个关键逻辑，hlist_for_each_entry的遍历，及dentry_path_raw来获取完整的当前这个dentry所在的super_block下完整的路径。
这里有必要说一下，file，fd，inode，dentry，super_block这几个概念：
file和fd都是进程强相关的概念；
inode是磁盘上的文件概念，不区分具体进程；
dentry是内核用来管理文件路径结构所用到的概念，一个dentry记录了一级目录，dentry连在一起就是一个完整的super_block下的路径
super_block是文件系统挂载伴随产生的一个概念，一个挂载就产生一个super_block，super_block也是一级级的，dentry所属的一个super_block，而这个所属的super_block的root dentry还是可能所属于另一个super_block的。
上图里hlist_for_each_entry的遍历是因为一个inode对应的操作系统文件系统上会可能有多个dentry，所以需要遍历，上图代码写得还是比较粗糙的，主要是为了打通和展示概念和逻辑并不是严谨的实现，若是严谨的实现还需要稍作改造。
上图里的dentry_path_raw的实现如下：
dentry_path_raw调用到的__dentry_path函数如下实现：
从上图的实现里可以清晰的看到，它有一个往parent dentry遍历的一个动作。
三、成果展示
下面我们展示一下成果，可以发现如 增加等IO状态的唤醒堆栈打印及缺页异常导致iowait分析-CSDN博客 博客里第三章里描述的一样，读磁盘对应的文件缺页异常的读的可能是数据文件，也可能是程序本身，也可能是so库，等等
下图是程序bin的filemap_fault情形：
下图是so库的场景：
下图是读取文件的情况：
