linux/fs/proc/loadavg.c
Alexey Dobriyan 9a1015b32f proc: fix /proc/loadavg regression
Commit 95846ecf9d ("pid: replace pid bitmap implementation with IDR
API") changed last field of /proc/loadavg (last pid allocated) to be off
by one:

	# unshare -p -f --mount-proc cat /proc/loadavg
	0.00 0.00 0.00 1/60 2	<===

It should be 1 after first fork into pid namespace.

This is formally a regression but given how useless this field is I
don't think anyone is affected.

Bug was found by /proc testsuite!

Link: http://lkml.kernel.org/r/20180413175408.GA27246@avx2
Fixes: 95846ecf9d ("pid: replace pid bitmap implementation with IDR API")
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Gargi Sharma <gs051095@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-20 17:18:36 -07:00

49 lines
1.2 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/pid_namespace.h>
#include <linux/proc_fs.h>
#include <linux/sched.h>
#include <linux/sched/loadavg.h>
#include <linux/sched/stat.h>
#include <linux/seq_file.h>
#include <linux/seqlock.h>
#include <linux/time.h>
#define LOAD_INT(x) ((x) >> FSHIFT)
#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)
static int loadavg_proc_show(struct seq_file *m, void *v)
{
unsigned long avnrun[3];
get_avenrun(avnrun, FIXED_1/200, 0);
seq_printf(m, "%lu.%02lu %lu.%02lu %lu.%02lu %ld/%d %d\n",
LOAD_INT(avnrun[0]), LOAD_FRAC(avnrun[0]),
LOAD_INT(avnrun[1]), LOAD_FRAC(avnrun[1]),
LOAD_INT(avnrun[2]), LOAD_FRAC(avnrun[2]),
nr_running(), nr_threads,
idr_get_cursor(&task_active_pid_ns(current)->idr) - 1);
return 0;
}
static int loadavg_proc_open(struct inode *inode, struct file *file)
{
return single_open(file, loadavg_proc_show, NULL);
}
static const struct file_operations loadavg_proc_fops = {
.open = loadavg_proc_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static int __init proc_loadavg_init(void)
{
proc_create("loadavg", 0, NULL, &loadavg_proc_fops);
return 0;
}
fs_initcall(proc_loadavg_init);