[Devel] [PATCH RH7] ms:/proc/PID/status: show all sets of pid according to ns

[Pavel Tikhomirov]

From: Chen Hanxiao <chenhanxiao at cn.fujitsu.com>

To c/r nested pidnses in CRIU we need NS..ids shown.
https://jira.sw.ru/browse/PSBM-62139

If some issues occurred inside a container guest, host user could not know
which process is in trouble just by guest pid: the users of container
guest only knew the pid inside containers.  This will bring obstacle for
trouble shooting.

This patch adds four fields: NStgid, NSpid, NSpgid and NSsid:

a) In init_pid_ns, nothing changed;

b) In one pidns, will tell the pid inside containers:
  NStgid: 21776   5       1
  NSpid:  21776   5       1
  NSpgid: 21776   5       1
  NSsid:  21729   1       0
  ** Process id is 21776 in level 0, 5 in level 1, 1 in level 2.

c) If pidns is nested, it depends on which pidns are you in.
  NStgid: 5       1
  NSpid:  5       1
  NSpgid: 5       1
  NSsid:  1       0
  ** Views from level 1

[akpm at linux-foundation.org: add CONFIG_PID_NS ifdef]
Signed-off-by: Chen Hanxiao <chenhanxiao at cn.fujitsu.com>
Acked-by: Serge Hallyn <serge.hallyn at canonical.com>
Acked-by: "Eric W. Biederman" <ebiederm at xmission.com>
Tested-by: Serge Hallyn <serge.hallyn at canonical.com>
Tested-by: Nathan Scott <nathans at redhat.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>

Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
---
 fs/proc/array.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/fs/proc/array.c b/fs/proc/array.c
index f18be7e..6e05ff8 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -235,6 +235,24 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
 			   from_kgid_munged(user_ns, GROUP_AT(group_info, g)));
 	put_cred(cred);
 
+#ifdef CONFIG_PID_NS
+	seq_puts(m, "\nNStgid:");
+	for (g = ns->level; g <= pid->level; g++)
+		seq_printf(m, "\t%d",
+			task_tgid_nr_ns(p, pid->numbers[g].ns));
+	seq_puts(m, "\nNSpid:");
+	for (g = ns->level; g <= pid->level; g++)
+		seq_printf(m, "\t%d",
+			task_pid_nr_ns(p, pid->numbers[g].ns));
+	seq_puts(m, "\nNSpgid:");
+	for (g = ns->level; g <= pid->level; g++)
+		seq_printf(m, "\t%d",
+			task_pgrp_nr_ns(p, pid->numbers[g].ns));
+	seq_puts(m, "\nNSsid:");
+	for (g = ns->level; g <= pid->level; g++)
+		seq_printf(m, "\t%d",
+			task_session_nr_ns(p, pid->numbers[g].ns));
+#endif
 	seq_putc(m, '\n');
 
 #ifdef CONFIG_VE
-- 
2.9.4