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Commit 0e464814 authored by KaiGai Kohei's avatar KaiGai Kohei Committed by Linus Torvalds
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[PATCH] pacct: add pacct_struct to fix some pacct bugs. 

The pacct facility need an i/o operation when an accounting record is
generated.  There is a possibility to wake OOM killer up.  If OOM killer is
activated, it kills some processes to make them release process memory
regions.

But acct_process() is called in the killed processes context before calling
exit_mm(), so those processes cannot release own memory.  In the results, any
processes stop in this point and it finally cause a system stall.
parent 6bc39274

include/linux/acct.h

+4 −0
Original line number Diff line number Diff line
@@ -121,12 +121,16 @@ struct vfsmount; 
struct super_block;

extern void acct_auto_close_mnt(struct vfsmount *m);

extern void acct_auto_close(struct super_block *sb);

extern void acct_init_pacct(struct pacct_struct *pacct);

extern void acct_collect();

extern void acct_process(long exitcode);

extern void acct_update_integrals(struct task_struct *tsk);

extern void acct_clear_integrals(struct task_struct *tsk);

#else

#define acct_auto_close_mnt(x)	do { } while (0)

#define acct_auto_close(x)	do { } while (0)

#define acct_init_pacct(x)	do { } while (0)

#define acct_collect()		do { } while (0)

#define acct_process(x)		do { } while (0)

#define acct_update_integrals(x)		do { } while (0)

#define acct_clear_integrals(task)	do { } while (0)

include/linux/sched.h

+7 −0
Original line number Diff line number Diff line
@@ -358,6 +358,10 @@ struct sighand_struct { 
	spinlock_t		siglock;

};



struct pacct_struct {

	unsigned long		ac_mem;

};



/*

 * NOTE! "signal_struct" does not have it's own

 * locking, because a shared signal_struct always
@@ -449,6 +453,9 @@ struct signal_struct { 
	struct key *session_keyring;	/* keyring inherited over fork */

	struct key *process_keyring;	/* keyring private to this process */

#endif

#ifdef CONFIG_BSD_PROCESS_ACCT

	struct pacct_struct pacct;	/* per-process accounting information */

#endif

};



/* Context switch must be unlocked if interrupts are to be enabled */

kernel/acct.c

+36 −15
Original line number Diff line number Diff line
@@ -421,9 +421,9 @@ static u32 encode_float(u64 value) 
 */

static void do_acct_process(long exitcode, struct file *file)

{

	struct pacct_struct *pacct = &current->signal->pacct;

	acct_t ac;

	mm_segment_t fs;

	unsigned long vsize;

	unsigned long flim;

	u64 elapsed;

	u64 run_time;
@@ -505,20 +505,9 @@ static void do_acct_process(long exitcode, struct file *file) 
		ac.ac_flag |= ACORE;

	if (current->flags & PF_SIGNALED)

		ac.ac_flag |= AXSIG;



	vsize = 0;

	if (current->mm) {

		struct vm_area_struct *vma;

		down_read(&current->mm->mmap_sem);

		vma = current->mm->mmap;

		while (vma) {

			vsize += vma->vm_end - vma->vm_start;

			vma = vma->vm_next;

		}

		up_read(&current->mm->mmap_sem);

	}

	vsize = vsize / 1024;

	ac.ac_mem = encode_comp_t(vsize);

	spin_lock(&current->sighand->siglock);

	ac.ac_mem = encode_comp_t(pacct->ac_mem);

	spin_unlock(&current->sighand->siglock);

	ac.ac_io = encode_comp_t(0 /* current->io_usage */);	/* %% */

	ac.ac_rw = encode_comp_t(ac.ac_io / 1024);

	ac.ac_minflt = encode_comp_t(current->signal->min_flt +
@@ -545,6 +534,38 @@ static void do_acct_process(long exitcode, struct file *file) 
	set_fs(fs);

}



/**

 * acct_init_pacct - initialize a new pacct_struct

 */

void acct_init_pacct(struct pacct_struct *pacct)

{

	memset(pacct, 0, sizeof(struct pacct_struct));

}



/**

 * acct_collect - collect accounting information into pacct_struct

 */

void acct_collect(void)

{

	struct pacct_struct *pacct = &current->signal->pacct;

	unsigned long vsize = 0;



	if (current->mm) {

		struct vm_area_struct *vma;

		down_read(&current->mm->mmap_sem);

		vma = current->mm->mmap;

		while (vma) {

			vsize += vma->vm_end - vma->vm_start;

			vma = vma->vm_next;

		}

		up_read(&current->mm->mmap_sem);

	}



	spin_lock(&current->sighand->siglock);

	pacct->ac_mem = vsize / 1024;

	spin_unlock(&current->sighand->siglock);

}



/**

 * acct_process - now just a wrapper around do_acct_process

 * @exitcode: task exit code

kernel/exit.c

+3 −1
Original line number Diff line number Diff line
@@ -894,7 +894,7 @@ fastcall NORET_TYPE void do_exit(long code) 
	if (group_dead) {

 		hrtimer_cancel(&tsk->signal->real_timer);

		exit_itimers(tsk->signal);

		acct_process(code);

		acct_collect();

	}

	if (unlikely(tsk->robust_list))

		exit_robust_list(tsk);
@@ -906,6 +906,8 @@ fastcall NORET_TYPE void do_exit(long code) 
		audit_free(tsk);

	exit_mm(tsk);



	if (group_dead)

		acct_process(code);

	exit_sem(tsk);

	__exit_files(tsk);

	__exit_fs(tsk);

kernel/fork.c

+1 −0
Original line number Diff line number Diff line
@@ -874,6 +874,7 @@ static inline int copy_signal(unsigned long clone_flags, struct task_struct * ts 
		tsk->it_prof_expires =

			secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);

	}

	acct_init_pacct(&sig->pacct);



	return 0;

}