xref: /openbmc/linux/kernel/acct.c (revision d37cf9b63113f13d742713881ce691fc615d8b3b)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/kernel/acct.c
4  *
5  *  BSD Process Accounting for Linux
6  *
7  *  Author: Marco van Wieringen <mvw@planets.elm.net>
8  *
9  *  Some code based on ideas and code from:
10  *  Thomas K. Dyas <tdyas@eden.rutgers.edu>
11  *
12  *  This file implements BSD-style process accounting. Whenever any
13  *  process exits, an accounting record of type "struct acct" is
14  *  written to the file specified with the acct() system call. It is
15  *  up to user-level programs to do useful things with the accounting
16  *  log. The kernel just provides the raw accounting information.
17  *
18  * (C) Copyright 1995 - 1997 Marco van Wieringen - ELM Consultancy B.V.
19  *
20  *  Plugged two leaks. 1) It didn't return acct_file into the free_filps if
21  *  the file happened to be read-only. 2) If the accounting was suspended
22  *  due to the lack of space it happily allowed to reopen it and completely
23  *  lost the old acct_file. 3/10/98, Al Viro.
24  *
25  *  Now we silently close acct_file on attempt to reopen. Cleaned sys_acct().
26  *  XTerms and EMACS are manifestations of pure evil. 21/10/98, AV.
27  *
28  *  Fixed a nasty interaction with sys_umount(). If the accounting
29  *  was suspeneded we failed to stop it on umount(). Messy.
30  *  Another one: remount to readonly didn't stop accounting.
31  *	Question: what should we do if we have CAP_SYS_ADMIN but not
32  *  CAP_SYS_PACCT? Current code does the following: umount returns -EBUSY
33  *  unless we are messing with the root. In that case we are getting a
34  *  real mess with do_remount_sb(). 9/11/98, AV.
35  *
36  *  Fixed a bunch of races (and pair of leaks). Probably not the best way,
37  *  but this one obviously doesn't introduce deadlocks. Later. BTW, found
38  *  one race (and leak) in BSD implementation.
39  *  OK, that's better. ANOTHER race and leak in BSD variant. There always
40  *  is one more bug... 10/11/98, AV.
41  *
42  *	Oh, fsck... Oopsable SMP race in do_process_acct() - we must hold
43  * ->mmap_lock to walk the vma list of current->mm. Nasty, since it leaks
44  * a struct file opened for write. Fixed. 2/6/2000, AV.
45  */
46 
47 #include <linux/mm.h>
48 #include <linux/slab.h>
49 #include <linux/acct.h>
50 #include <linux/capability.h>
51 #include <linux/file.h>
52 #include <linux/tty.h>
53 #include <linux/security.h>
54 #include <linux/vfs.h>
55 #include <linux/jiffies.h>
56 #include <linux/times.h>
57 #include <linux/syscalls.h>
58 #include <linux/mount.h>
59 #include <linux/uaccess.h>
60 #include <linux/sched/cputime.h>
61 
62 #include <asm/div64.h>
63 #include <linux/pid_namespace.h>
64 #include <linux/fs_pin.h>
65 
66 /*
67  * These constants control the amount of freespace that suspend and
68  * resume the process accounting system, and the time delay between
69  * each check.
70  * Turned into sysctl-controllable parameters. AV, 12/11/98
71  */
72 
73 static int acct_parm[3] = {4, 2, 30};
74 #define RESUME		(acct_parm[0])	/* >foo% free space - resume */
75 #define SUSPEND		(acct_parm[1])	/* <foo% free space - suspend */
76 #define ACCT_TIMEOUT	(acct_parm[2])	/* foo second timeout between checks */
77 
78 #ifdef CONFIG_SYSCTL
79 static struct ctl_table kern_acct_table[] = {
80 	{
81 		.procname       = "acct",
82 		.data           = &acct_parm,
83 		.maxlen         = 3*sizeof(int),
84 		.mode           = 0644,
85 		.proc_handler   = proc_dointvec,
86 	},
87 	{ }
88 };
89 
kernel_acct_sysctls_init(void)90 static __init int kernel_acct_sysctls_init(void)
91 {
92 	register_sysctl_init("kernel", kern_acct_table);
93 	return 0;
94 }
95 late_initcall(kernel_acct_sysctls_init);
96 #endif /* CONFIG_SYSCTL */
97 
98 /*
99  * External references and all of the globals.
100  */
101 
102 struct bsd_acct_struct {
103 	struct fs_pin		pin;
104 	atomic_long_t		count;
105 	struct rcu_head		rcu;
106 	struct mutex		lock;
107 	bool			active;
108 	bool			check_space;
109 	unsigned long		needcheck;
110 	struct file		*file;
111 	struct pid_namespace	*ns;
112 	struct work_struct	work;
113 	struct completion	done;
114 	acct_t			ac;
115 };
116 
117 static void fill_ac(struct bsd_acct_struct *acct);
118 static void acct_write_process(struct bsd_acct_struct *acct);
119 
120 /*
121  * Check the amount of free space and suspend/resume accordingly.
122  */
check_free_space(struct bsd_acct_struct * acct)123 static bool check_free_space(struct bsd_acct_struct *acct)
124 {
125 	struct kstatfs sbuf;
126 
127 	if (!acct->check_space)
128 		return acct->active;
129 
130 	/* May block */
131 	if (vfs_statfs(&acct->file->f_path, &sbuf))
132 		return acct->active;
133 
134 	if (acct->active) {
135 		u64 suspend = sbuf.f_blocks * SUSPEND;
136 		do_div(suspend, 100);
137 		if (sbuf.f_bavail <= suspend) {
138 			acct->active = false;
139 			pr_info("Process accounting paused\n");
140 		}
141 	} else {
142 		u64 resume = sbuf.f_blocks * RESUME;
143 		do_div(resume, 100);
144 		if (sbuf.f_bavail >= resume) {
145 			acct->active = true;
146 			pr_info("Process accounting resumed\n");
147 		}
148 	}
149 
150 	acct->needcheck = jiffies + ACCT_TIMEOUT*HZ;
151 	return acct->active;
152 }
153 
acct_put(struct bsd_acct_struct * p)154 static void acct_put(struct bsd_acct_struct *p)
155 {
156 	if (atomic_long_dec_and_test(&p->count))
157 		kfree_rcu(p, rcu);
158 }
159 
to_acct(struct fs_pin * p)160 static inline struct bsd_acct_struct *to_acct(struct fs_pin *p)
161 {
162 	return p ? container_of(p, struct bsd_acct_struct, pin) : NULL;
163 }
164 
acct_get(struct pid_namespace * ns)165 static struct bsd_acct_struct *acct_get(struct pid_namespace *ns)
166 {
167 	struct bsd_acct_struct *res;
168 again:
169 	smp_rmb();
170 	rcu_read_lock();
171 	res = to_acct(READ_ONCE(ns->bacct));
172 	if (!res) {
173 		rcu_read_unlock();
174 		return NULL;
175 	}
176 	if (!atomic_long_inc_not_zero(&res->count)) {
177 		rcu_read_unlock();
178 		cpu_relax();
179 		goto again;
180 	}
181 	rcu_read_unlock();
182 	mutex_lock(&res->lock);
183 	if (res != to_acct(READ_ONCE(ns->bacct))) {
184 		mutex_unlock(&res->lock);
185 		acct_put(res);
186 		goto again;
187 	}
188 	return res;
189 }
190 
acct_pin_kill(struct fs_pin * pin)191 static void acct_pin_kill(struct fs_pin *pin)
192 {
193 	struct bsd_acct_struct *acct = to_acct(pin);
194 	mutex_lock(&acct->lock);
195 	/*
196 	 * Fill the accounting struct with the exiting task's info
197 	 * before punting to the workqueue.
198 	 */
199 	fill_ac(acct);
200 	schedule_work(&acct->work);
201 	wait_for_completion(&acct->done);
202 	cmpxchg(&acct->ns->bacct, pin, NULL);
203 	mutex_unlock(&acct->lock);
204 	pin_remove(pin);
205 	acct_put(acct);
206 }
207 
close_work(struct work_struct * work)208 static void close_work(struct work_struct *work)
209 {
210 	struct bsd_acct_struct *acct = container_of(work, struct bsd_acct_struct, work);
211 	struct file *file = acct->file;
212 
213 	/* We were fired by acct_pin_kill() which holds acct->lock. */
214 	acct_write_process(acct);
215 	if (file->f_op->flush)
216 		file->f_op->flush(file, NULL);
217 	__fput_sync(file);
218 	complete(&acct->done);
219 }
220 
acct_on(struct filename * pathname)221 static int acct_on(struct filename *pathname)
222 {
223 	struct file *file;
224 	struct vfsmount *mnt, *internal;
225 	struct pid_namespace *ns = task_active_pid_ns(current);
226 	struct bsd_acct_struct *acct;
227 	struct fs_pin *old;
228 	int err;
229 
230 	acct = kzalloc(sizeof(struct bsd_acct_struct), GFP_KERNEL);
231 	if (!acct)
232 		return -ENOMEM;
233 
234 	/* Difference from BSD - they don't do O_APPEND */
235 	file = file_open_name(pathname, O_WRONLY|O_APPEND|O_LARGEFILE, 0);
236 	if (IS_ERR(file)) {
237 		kfree(acct);
238 		return PTR_ERR(file);
239 	}
240 
241 	if (!S_ISREG(file_inode(file)->i_mode)) {
242 		kfree(acct);
243 		filp_close(file, NULL);
244 		return -EACCES;
245 	}
246 
247 	/* Exclude kernel kernel internal filesystems. */
248 	if (file_inode(file)->i_sb->s_flags & (SB_NOUSER | SB_KERNMOUNT)) {
249 		kfree(acct);
250 		filp_close(file, NULL);
251 		return -EINVAL;
252 	}
253 
254 	/* Exclude procfs and sysfs. */
255 	if (file_inode(file)->i_sb->s_iflags & SB_I_USERNS_VISIBLE) {
256 		kfree(acct);
257 		filp_close(file, NULL);
258 		return -EINVAL;
259 	}
260 
261 	if (!(file->f_mode & FMODE_CAN_WRITE)) {
262 		kfree(acct);
263 		filp_close(file, NULL);
264 		return -EIO;
265 	}
266 	internal = mnt_clone_internal(&file->f_path);
267 	if (IS_ERR(internal)) {
268 		kfree(acct);
269 		filp_close(file, NULL);
270 		return PTR_ERR(internal);
271 	}
272 	err = __mnt_want_write(internal);
273 	if (err) {
274 		mntput(internal);
275 		kfree(acct);
276 		filp_close(file, NULL);
277 		return err;
278 	}
279 	mnt = file->f_path.mnt;
280 	file->f_path.mnt = internal;
281 
282 	atomic_long_set(&acct->count, 1);
283 	init_fs_pin(&acct->pin, acct_pin_kill);
284 	acct->file = file;
285 	acct->needcheck = jiffies;
286 	acct->ns = ns;
287 	mutex_init(&acct->lock);
288 	INIT_WORK(&acct->work, close_work);
289 	init_completion(&acct->done);
290 	mutex_lock_nested(&acct->lock, 1);	/* nobody has seen it yet */
291 	pin_insert(&acct->pin, mnt);
292 
293 	rcu_read_lock();
294 	old = xchg(&ns->bacct, &acct->pin);
295 	mutex_unlock(&acct->lock);
296 	pin_kill(old);
297 	__mnt_drop_write(mnt);
298 	mntput(mnt);
299 	return 0;
300 }
301 
302 static DEFINE_MUTEX(acct_on_mutex);
303 
304 /**
305  * sys_acct - enable/disable process accounting
306  * @name: file name for accounting records or NULL to shutdown accounting
307  *
308  * sys_acct() is the only system call needed to implement process
309  * accounting. It takes the name of the file where accounting records
310  * should be written. If the filename is NULL, accounting will be
311  * shutdown.
312  *
313  * Returns: 0 for success or negative errno values for failure.
314  */
SYSCALL_DEFINE1(acct,const char __user *,name)315 SYSCALL_DEFINE1(acct, const char __user *, name)
316 {
317 	int error = 0;
318 
319 	if (!capable(CAP_SYS_PACCT))
320 		return -EPERM;
321 
322 	if (name) {
323 		struct filename *tmp = getname(name);
324 
325 		if (IS_ERR(tmp))
326 			return PTR_ERR(tmp);
327 		mutex_lock(&acct_on_mutex);
328 		error = acct_on(tmp);
329 		mutex_unlock(&acct_on_mutex);
330 		putname(tmp);
331 	} else {
332 		rcu_read_lock();
333 		pin_kill(task_active_pid_ns(current)->bacct);
334 	}
335 
336 	return error;
337 }
338 
acct_exit_ns(struct pid_namespace * ns)339 void acct_exit_ns(struct pid_namespace *ns)
340 {
341 	rcu_read_lock();
342 	pin_kill(ns->bacct);
343 }
344 
345 /*
346  *  encode an u64 into a comp_t
347  *
348  *  This routine has been adopted from the encode_comp_t() function in
349  *  the kern_acct.c file of the FreeBSD operating system. The encoding
350  *  is a 13-bit fraction with a 3-bit (base 8) exponent.
351  */
352 
353 #define	MANTSIZE	13			/* 13 bit mantissa. */
354 #define	EXPSIZE		3			/* Base 8 (3 bit) exponent. */
355 #define	MAXFRACT	((1 << MANTSIZE) - 1)	/* Maximum fractional value. */
356 
encode_comp_t(u64 value)357 static comp_t encode_comp_t(u64 value)
358 {
359 	int exp, rnd;
360 
361 	exp = rnd = 0;
362 	while (value > MAXFRACT) {
363 		rnd = value & (1 << (EXPSIZE - 1));	/* Round up? */
364 		value >>= EXPSIZE;	/* Base 8 exponent == 3 bit shift. */
365 		exp++;
366 	}
367 
368 	/*
369 	 * If we need to round up, do it (and handle overflow correctly).
370 	 */
371 	if (rnd && (++value > MAXFRACT)) {
372 		value >>= EXPSIZE;
373 		exp++;
374 	}
375 
376 	if (exp > (((comp_t) ~0U) >> MANTSIZE))
377 		return (comp_t) ~0U;
378 	/*
379 	 * Clean it up and polish it off.
380 	 */
381 	exp <<= MANTSIZE;		/* Shift the exponent into place */
382 	exp += value;			/* and add on the mantissa. */
383 	return exp;
384 }
385 
386 #if ACCT_VERSION == 1 || ACCT_VERSION == 2
387 /*
388  * encode an u64 into a comp2_t (24 bits)
389  *
390  * Format: 5 bit base 2 exponent, 20 bits mantissa.
391  * The leading bit of the mantissa is not stored, but implied for
392  * non-zero exponents.
393  * Largest encodable value is 50 bits.
394  */
395 
396 #define MANTSIZE2       20                      /* 20 bit mantissa. */
397 #define EXPSIZE2        5                       /* 5 bit base 2 exponent. */
398 #define MAXFRACT2       ((1ul << MANTSIZE2) - 1) /* Maximum fractional value. */
399 #define MAXEXP2         ((1 << EXPSIZE2) - 1)    /* Maximum exponent. */
400 
encode_comp2_t(u64 value)401 static comp2_t encode_comp2_t(u64 value)
402 {
403 	int exp, rnd;
404 
405 	exp = (value > (MAXFRACT2>>1));
406 	rnd = 0;
407 	while (value > MAXFRACT2) {
408 		rnd = value & 1;
409 		value >>= 1;
410 		exp++;
411 	}
412 
413 	/*
414 	 * If we need to round up, do it (and handle overflow correctly).
415 	 */
416 	if (rnd && (++value > MAXFRACT2)) {
417 		value >>= 1;
418 		exp++;
419 	}
420 
421 	if (exp > MAXEXP2) {
422 		/* Overflow. Return largest representable number instead. */
423 		return (1ul << (MANTSIZE2+EXPSIZE2-1)) - 1;
424 	} else {
425 		return (value & (MAXFRACT2>>1)) | (exp << (MANTSIZE2-1));
426 	}
427 }
428 #elif ACCT_VERSION == 3
429 /*
430  * encode an u64 into a 32 bit IEEE float
431  */
encode_float(u64 value)432 static u32 encode_float(u64 value)
433 {
434 	unsigned exp = 190;
435 	unsigned u;
436 
437 	if (value == 0)
438 		return 0;
439 	while ((s64)value > 0) {
440 		value <<= 1;
441 		exp--;
442 	}
443 	u = (u32)(value >> 40) & 0x7fffffu;
444 	return u | (exp << 23);
445 }
446 #endif
447 
448 /*
449  *  Write an accounting entry for an exiting process
450  *
451  *  The acct_process() call is the workhorse of the process
452  *  accounting system. The struct acct is built here and then written
453  *  into the accounting file. This function should only be called from
454  *  do_exit() or when switching to a different output file.
455  */
456 
fill_ac(struct bsd_acct_struct * acct)457 static void fill_ac(struct bsd_acct_struct *acct)
458 {
459 	struct pacct_struct *pacct = &current->signal->pacct;
460 	struct file *file = acct->file;
461 	acct_t *ac = &acct->ac;
462 	u64 elapsed, run_time;
463 	time64_t btime;
464 	struct tty_struct *tty;
465 
466 	lockdep_assert_held(&acct->lock);
467 
468 	if (time_is_after_jiffies(acct->needcheck)) {
469 		acct->check_space = false;
470 
471 		/* Don't fill in @ac if nothing will be written. */
472 		if (!acct->active)
473 			return;
474 	} else {
475 		acct->check_space = true;
476 	}
477 
478 	/*
479 	 * Fill the accounting struct with the needed info as recorded
480 	 * by the different kernel functions.
481 	 */
482 	memset(ac, 0, sizeof(acct_t));
483 
484 	ac->ac_version = ACCT_VERSION | ACCT_BYTEORDER;
485 	strscpy(ac->ac_comm, current->comm, sizeof(ac->ac_comm));
486 
487 	/* calculate run_time in nsec*/
488 	run_time = ktime_get_ns();
489 	run_time -= current->group_leader->start_time;
490 	/* convert nsec -> AHZ */
491 	elapsed = nsec_to_AHZ(run_time);
492 #if ACCT_VERSION == 3
493 	ac->ac_etime = encode_float(elapsed);
494 #else
495 	ac->ac_etime = encode_comp_t(elapsed < (unsigned long) -1l ?
496 				(unsigned long) elapsed : (unsigned long) -1l);
497 #endif
498 #if ACCT_VERSION == 1 || ACCT_VERSION == 2
499 	{
500 		/* new enlarged etime field */
501 		comp2_t etime = encode_comp2_t(elapsed);
502 
503 		ac->ac_etime_hi = etime >> 16;
504 		ac->ac_etime_lo = (u16) etime;
505 	}
506 #endif
507 	do_div(elapsed, AHZ);
508 	btime = ktime_get_real_seconds() - elapsed;
509 	ac->ac_btime = clamp_t(time64_t, btime, 0, U32_MAX);
510 #if ACCT_VERSION == 2
511 	ac->ac_ahz = AHZ;
512 #endif
513 
514 	spin_lock_irq(&current->sighand->siglock);
515 	tty = current->signal->tty;	/* Safe as we hold the siglock */
516 	ac->ac_tty = tty ? old_encode_dev(tty_devnum(tty)) : 0;
517 	ac->ac_utime = encode_comp_t(nsec_to_AHZ(pacct->ac_utime));
518 	ac->ac_stime = encode_comp_t(nsec_to_AHZ(pacct->ac_stime));
519 	ac->ac_flag = pacct->ac_flag;
520 	ac->ac_mem = encode_comp_t(pacct->ac_mem);
521 	ac->ac_minflt = encode_comp_t(pacct->ac_minflt);
522 	ac->ac_majflt = encode_comp_t(pacct->ac_majflt);
523 	ac->ac_exitcode = pacct->ac_exitcode;
524 	spin_unlock_irq(&current->sighand->siglock);
525 
526 	/* we really need to bite the bullet and change layout */
527 	ac->ac_uid = from_kuid_munged(file->f_cred->user_ns, current_uid());
528 	ac->ac_gid = from_kgid_munged(file->f_cred->user_ns, current_gid());
529 #if ACCT_VERSION == 1 || ACCT_VERSION == 2
530 	/* backward-compatible 16 bit fields */
531 	ac->ac_uid16 = ac->ac_uid;
532 	ac->ac_gid16 = ac->ac_gid;
533 #elif ACCT_VERSION == 3
534 	{
535 		struct pid_namespace *ns = acct->ns;
536 
537 		ac->ac_pid = task_tgid_nr_ns(current, ns);
538 		rcu_read_lock();
539 		ac->ac_ppid = task_tgid_nr_ns(rcu_dereference(current->real_parent), ns);
540 		rcu_read_unlock();
541 	}
542 #endif
543 }
544 
acct_write_process(struct bsd_acct_struct * acct)545 static void acct_write_process(struct bsd_acct_struct *acct)
546 {
547 	struct file *file = acct->file;
548 	const struct cred *cred;
549 	acct_t *ac = &acct->ac;
550 
551 	/* Perform file operations on behalf of whoever enabled accounting */
552 	cred = override_creds(file->f_cred);
553 
554 	/*
555 	 * First check to see if there is enough free_space to continue
556 	 * the process accounting system. Then get freeze protection. If
557 	 * the fs is frozen, just skip the write as we could deadlock
558 	 * the system otherwise.
559 	 */
560 	if (check_free_space(acct) && file_start_write_trylock(file)) {
561 		/* it's been opened O_APPEND, so position is irrelevant */
562 		loff_t pos = 0;
563 		__kernel_write(file, ac, sizeof(acct_t), &pos);
564 		file_end_write(file);
565 	}
566 
567 	revert_creds(cred);
568 }
569 
do_acct_process(struct bsd_acct_struct * acct)570 static void do_acct_process(struct bsd_acct_struct *acct)
571 {
572 	unsigned long flim;
573 
574 	/* Accounting records are not subject to resource limits. */
575 	flim = rlimit(RLIMIT_FSIZE);
576 	current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
577 	fill_ac(acct);
578 	acct_write_process(acct);
579 	current->signal->rlim[RLIMIT_FSIZE].rlim_cur = flim;
580 }
581 
582 /**
583  * acct_collect - collect accounting information into pacct_struct
584  * @exitcode: task exit code
585  * @group_dead: not 0, if this thread is the last one in the process.
586  */
acct_collect(long exitcode,int group_dead)587 void acct_collect(long exitcode, int group_dead)
588 {
589 	struct pacct_struct *pacct = &current->signal->pacct;
590 	u64 utime, stime;
591 	unsigned long vsize = 0;
592 
593 	if (group_dead && current->mm) {
594 		struct mm_struct *mm = current->mm;
595 		VMA_ITERATOR(vmi, mm, 0);
596 		struct vm_area_struct *vma;
597 
598 		mmap_read_lock(mm);
599 		for_each_vma(vmi, vma)
600 			vsize += vma->vm_end - vma->vm_start;
601 		mmap_read_unlock(mm);
602 	}
603 
604 	spin_lock_irq(&current->sighand->siglock);
605 	if (group_dead)
606 		pacct->ac_mem = vsize / 1024;
607 	if (thread_group_leader(current)) {
608 		pacct->ac_exitcode = exitcode;
609 		if (current->flags & PF_FORKNOEXEC)
610 			pacct->ac_flag |= AFORK;
611 	}
612 	if (current->flags & PF_SUPERPRIV)
613 		pacct->ac_flag |= ASU;
614 	if (current->flags & PF_DUMPCORE)
615 		pacct->ac_flag |= ACORE;
616 	if (current->flags & PF_SIGNALED)
617 		pacct->ac_flag |= AXSIG;
618 
619 	task_cputime(current, &utime, &stime);
620 	pacct->ac_utime += utime;
621 	pacct->ac_stime += stime;
622 	pacct->ac_minflt += current->min_flt;
623 	pacct->ac_majflt += current->maj_flt;
624 	spin_unlock_irq(&current->sighand->siglock);
625 }
626 
slow_acct_process(struct pid_namespace * ns)627 static void slow_acct_process(struct pid_namespace *ns)
628 {
629 	for ( ; ns; ns = ns->parent) {
630 		struct bsd_acct_struct *acct = acct_get(ns);
631 		if (acct) {
632 			do_acct_process(acct);
633 			mutex_unlock(&acct->lock);
634 			acct_put(acct);
635 		}
636 	}
637 }
638 
639 /**
640  * acct_process - handles process accounting for an exiting task
641  */
acct_process(void)642 void acct_process(void)
643 {
644 	struct pid_namespace *ns;
645 
646 	/*
647 	 * This loop is safe lockless, since current is still
648 	 * alive and holds its namespace, which in turn holds
649 	 * its parent.
650 	 */
651 	for (ns = task_active_pid_ns(current); ns != NULL; ns = ns->parent) {
652 		if (ns->bacct)
653 			break;
654 	}
655 	if (unlikely(ns))
656 		slow_acct_process(ns);
657 }
658