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

[Andrew Vagin]

Kirill, pls review this patch.

On Tue, May 09, 2017 at 02:44:47PM +0300, Pavel Tikhomirov wrote:
> 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
>