[PATCH] proc: fix /proc/loadavg regression

From: Alexey Dobriyan
Date: Fri Apr 13 2018 - 13:54:16 EST


commit 95846ecf9dac5089aed4b144d912225f8ef86ae4
"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!

Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
---

arch/powerpc/platforms/cell/spufs/sched.c | 2 +-
fs/proc/loadavg.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -1093,7 +1093,7 @@ static int show_spu_loadavg(struct seq_file *s, void *private)
LOAD_INT(c), LOAD_FRAC(c),
count_active_contexts(),
atomic_read(&nr_spu_contexts),
- idr_get_cursor(&task_active_pid_ns(current)->idr));
+ idr_get_cursor(&task_active_pid_ns(current)->idr) - 1);
return 0;
}

--- a/fs/proc/loadavg.c
+++ b/fs/proc/loadavg.c
@@ -24,7 +24,7 @@ static int loadavg_proc_show(struct seq_file *m, void *v)
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));
+ idr_get_cursor(&task_active_pid_ns(current)->idr) - 1);
return 0;
}