__cgroup_procs_start() makes an extra cgroup_procs_next() call and skip current entry
[test@localhost ~]$ dd if=/sys/fs/cgroup/cgroup.procs bs=8 count=1
2
3
4
5
1+0 records in
1+0 records out
8 bytes copied, 0,000267297 s, 29,9 kB/s
[test@localhost ~]$ dd if=/sys/fs/cgroup/cgroup.procs bs=1 count=8
2
4 <<< NB! 3 was skipped
6 <<< ... and 5 too
8 <<< ... and 7
8+0 records in
8+0 records out
8 bytes copied, 5,2123e-05 s, 153 kB/s
[test@localhost ~]$ mount | grep cgroup
cgroup2 on /sys/fs/cgroup type cgroup2 (rw,nosuid,nodev,noexec,relatime,seclabel,nsdelegate)
[test@localhost ~]$ uname -a
Linux localhost.localdomain 5.4.7-200.fc31.x86_64 #1 SMP Tue Dec 31 22:25:12 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
Signed-off-by: Vasily Averin <vvs@xxxxxxxxxxxxx>
---
kernel/cgroup/cgroup.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 8361eac..f79ec3b 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -4628,7 +4628,8 @@ static void *__cgroup_procs_start(struct seq_file *s, loff_t *pos,
} else if (!(*pos)++) {
css_task_iter_end(it);
css_task_iter_start(&cgrp->self, iter_flags, it);
- }
+ } else
+ return it->cur_task;
return cgroup_procs_next(s, NULL, NULL);
}
--
1.8.3.1
