[CRIU] [PATCH] pstree/pidns: initialize tid->ns[i].virt for threads

[Pavel Tikhomirov]

That is for if-unset check in dump_task_thread(), which compares virt
and -1. It is ok not to initialize virt if kernel has NSpid in
/proc/pid/status as parse_pid_status() will rewrite zeroes, but on
VZ7 kernel it will fail:

https://ci.openvz.org/job/CRIU/job/CRIU-virtuozzo/job/criu-dev/2021/

======================== Run zdtm/static/clone_fs in h =========================
Start test
./clone_fs --pidfile=clone_fs.pid --outfile=clone_fs.out
Run criu dump
=[log]=> dump/zdtm/static/clone_fs/24/1/dump.log
------------------------ grep Error ------------------------
(00.007511) Dumping general registers for 25 in native mode
(00.007525) Dumping GP/FPU registers for 25
(00.007535) 25 has 0 sched policy
(00.007542) 	dumping 0 nice for 25
(00.007549) Error (criu/cr-dump.c:863): Parasite and /proc/[pid]/status gave different tids
------------------------ ERROR OVER ------------------------
Run criu restore
=[log]=> dump/zdtm/static/clone_fs/24/1/restore.log
------------------------ grep Error ------------------------
(00.000497) Add user ns 2 pid 24
(00.000500) Add pid ns 1 pid 24
(00.000503) Add ipc ns 4 pid 24
(00.000506) Add uts ns 5 pid 24
(00.000514) Error (criu/pstree.c:501): Can't skip zero pids levels (0) or find {parent,} ns (1)
(00.000520) Error (criu/pstree.c:813): BUG at criu/pstree.c:813
------------------------ ERROR OVER ------------------------

Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
---
 criu/seize.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/criu/seize.c b/criu/seize.c
index 6732151..8d3c6cc 100644
--- a/criu/seize.c
+++ b/criu/seize.c
@@ -688,7 +688,7 @@ static int parse_thread_status(int pid, struct seize_task_status *ss, void *thre
 static int collect_threads(struct pstree_item *item)
 {
 	struct pid **threads = NULL;
-	int nr_threads = 0, i = 0, ret, nr_inprogress, nr_stopped = 0;
+	int nr_threads = 0, i = 0, j, ret, nr_inprogress, nr_stopped = 0;
 	int level = item->pid->level, id;
 
 	ret = parse_threads(item->pid->real, &threads, &nr_threads);
@@ -713,6 +713,8 @@ static int collect_threads(struct pstree_item *item)
 		item->nr_threads = 1;
 		item->threads[0]->item = NULL;
 		item->threads[0]->level = level;
+		for (j = 0; j < level; j++)
+			item->threads[0]->ns[j].virt = -1;
 	}
 
 	nr_inprogress = 0;
@@ -739,6 +741,8 @@ static int collect_threads(struct pstree_item *item)
 		item->threads[id]->real = pid;
 		item->threads[id]->item = NULL;
 		item->threads[id]->level = level;
+		for (j = 0; j < level; j++)
+			item->threads[id]->ns[j].virt = -1;
 
 		ret = compel_wait_task(pid, item_ppid(item), parse_thread_status, NULL,
 				       &t_creds.s, &item->threads[id]);
-- 
2.9.3