Commit d85f50d5 authored by Neil Horman's avatar Neil Horman Committed by Linus Torvalds
Browse files

proc: export a processes resource limits via /proc/pid 



Currently, there exists no method for a process to query the resource
limits of another process.  They can be inferred via some mechanisms but
they cannot be explicitly determined.  Given that this information can be
usefull to know during the debugging of an application, I've written this
patch which exports all of a processes limits via /proc/<pid>/limits.

Signed-off-by: default avatarNeil Horman <nhorman@tuxdriver.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 14ed9d23

fs/proc/base.c

+75 −0
Original line number Diff line number Diff line
@@ -63,6 +63,7 @@ 
#include <linux/mm.h>

#include <linux/rcupdate.h>

#include <linux/kallsyms.h>

#include <linux/resource.h>

#include <linux/module.h>

#include <linux/mount.h>

#include <linux/security.h>
@@ -303,6 +304,78 @@ static int proc_oom_score(struct task_struct *task, char *buffer) 
	return sprintf(buffer, "%lu\n", points);

}



struct limit_names {

	char *name;

	char *unit;

};



static const struct limit_names lnames[RLIM_NLIMITS] = {

	[RLIMIT_CPU] = {"Max cpu time", "ms"},

	[RLIMIT_FSIZE] = {"Max file size", "bytes"},

	[RLIMIT_DATA] = {"Max data size", "bytes"},

	[RLIMIT_STACK] = {"Max stack size", "bytes"},

	[RLIMIT_CORE] = {"Max core file size", "bytes"},

	[RLIMIT_RSS] = {"Max resident set", "bytes"},

	[RLIMIT_NPROC] = {"Max processes", "processes"},

	[RLIMIT_NOFILE] = {"Max open files", "files"},

	[RLIMIT_MEMLOCK] = {"Max locked memory", "bytes"},

	[RLIMIT_AS] = {"Max address space", "bytes"},

	[RLIMIT_LOCKS] = {"Max file locks", "locks"},

	[RLIMIT_SIGPENDING] = {"Max pending signals", "signals"},

	[RLIMIT_MSGQUEUE] = {"Max msgqueue size", "bytes"},

	[RLIMIT_NICE] = {"Max nice priority", NULL},

	[RLIMIT_RTPRIO] = {"Max realtime priority", NULL},

};



/* Display limits for a process */

static int proc_pid_limits(struct task_struct *task, char *buffer)

{

	unsigned int i;

	int count = 0;

	unsigned long flags;

	char *bufptr = buffer;



	struct rlimit rlim[RLIM_NLIMITS];



	rcu_read_lock();

	if (!lock_task_sighand(task,&flags)) {

		rcu_read_unlock();

		return 0;

	}

	memcpy(rlim, task->signal->rlim, sizeof(struct rlimit) * RLIM_NLIMITS);

	unlock_task_sighand(task, &flags);

	rcu_read_unlock();



	/*

	 * print the file header

	 */

	count += sprintf(&bufptr[count], "%-25s %-20s %-20s %-10s\n",

			"Limit", "Soft Limit", "Hard Limit", "Units");



	for (i = 0; i < RLIM_NLIMITS; i++) {

		if (rlim[i].rlim_cur == RLIM_INFINITY)

			count += sprintf(&bufptr[count], "%-25s %-20s ",

					 lnames[i].name, "unlimited");

		else

			count += sprintf(&bufptr[count], "%-25s %-20lu ",

					 lnames[i].name, rlim[i].rlim_cur);



		if (rlim[i].rlim_max == RLIM_INFINITY)

			count += sprintf(&bufptr[count], "%-20s ", "unlimited");

		else

			count += sprintf(&bufptr[count], "%-20lu ",

					 rlim[i].rlim_max);



		if (lnames[i].unit)

			count += sprintf(&bufptr[count], "%-10s\n",

					 lnames[i].unit);

		else

			count += sprintf(&bufptr[count], "\n");

	}



	return count;

}



/************************************************************************/

/*                       Here the fs part begins                        */

/************************************************************************/
@@ -2110,6 +2183,7 @@ static const struct pid_entry tgid_base_stuff[] = { 
	REG("environ",    S_IRUSR, environ),

	INF("auxv",       S_IRUSR, pid_auxv),

	INF("status",     S_IRUGO, pid_status),

	INF("limits",	  S_IRUSR, pid_limits),

#ifdef CONFIG_SCHED_DEBUG

	REG("sched",      S_IRUGO|S_IWUSR, pid_sched),

#endif
@@ -2435,6 +2509,7 @@ static const struct pid_entry tid_base_stuff[] = { 
	REG("environ",   S_IRUSR, environ),

	INF("auxv",      S_IRUSR, pid_auxv),

	INF("status",    S_IRUGO, pid_status),

	INF("limits",	 S_IRUSR, pid_limits),

#ifdef CONFIG_SCHED_DEBUG

	REG("sched",     S_IRUGO|S_IWUSR, pid_sched),

#endif

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