proc: fix /proc/loadavg regression

Commit 95846ecf9dac ("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: 95846ecf9dac508 ("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>

diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index 9033c8194eda5d7d39db99af0af9e6f33811a272..ccc42150336394ca0fa8a7263b5d408e59c30552 100644 (file)
--- 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;
 }
 

diff --git a/fs/proc/loadavg.c b/fs/proc/loadavg.c
index a000d7547479e8849acbea6dea406dc5b2bb7c46..b572cc865b928635c413f0d14d68b1ed46d5c7bf 100644 (file)
--- 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;
 }