Re: /proc/$PID/sched does not take PID namespace into account

From: Peter Zijlstra
Date: Mon Sep 09 2013 - 07:01:53 EST


On Tue, Sep 03, 2013 at 04:22:33PM +0200, Emmanuel Deloget wrote:
> The issue (if this is really an issue) lies in kernel/sched/debug.c,
> function proc_sched_show_task(). The code says [1]:
>
> SEQ_printf(m, "%s (%d, #threads: %d)\n", p->comm, p->pid,
> get_nr_threads(p));
>

> I see a few options:
>
> * either it's a bug and it should be corrected (I'm not sure how to
> do it; the printed PID should reflect the current PID namespace
> and I don't how how to get this information).

I suppose something like the below ought to work? -- completely
untested, please confirm.

---
Subject: sched, debug: Use PID namespaces

Emmanuel reported that /proc/sched_debug didn't report the right PIDs
when using namespaces, cure this.

Reported-by: Emmanuel Deloget <emmanuel.deloget@xxxxxxxxx>
Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
---
kernel/sched/debug.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index e076bdd..e30bf44 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -124,7 +124,7 @@ print_task(struct seq_file *m, struct rq *rq, struct task_struct *p)
SEQ_printf(m, " ");

SEQ_printf(m, "%15s %5d %9Ld.%06ld %9Ld %5d ",
- p->comm, p->pid,
+ p->comm, task_pid(p),,
SPLIT_NS(p->se.vruntime),
(long long)(p->nvcsw + p->nivcsw),
p->prio);
@@ -289,7 +289,7 @@ do { \
P(nr_load_updates);
P(nr_uninterruptible);
PN(next_balance);
- P(curr->pid);
+ P(task_pid(curr));
PN(clock);
P(cpu_load[0]);
P(cpu_load[1]);
@@ -492,7 +492,7 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m)
{
unsigned long nr_switches;

- SEQ_printf(m, "%s (%d, #threads: %d)\n", p->comm, p->pid,
+ SEQ_printf(m, "%s (%d, #threads: %d)\n", p->comm, task_pid(p),
get_nr_threads(p));
SEQ_printf(m,
"---------------------------------------------------------"
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