* Re: cgroup, kernfs: make mountinfo show properly scoped path for cgroup namespaces
@ 2016-05-12 0:10 Andrei Vagin
2016-05-12 5:29 ` [PATCH] kernfs: kernfs_sop_show_path: don't return 0 after seq_dentry call Serge E. Hallyn
0 siblings, 1 reply; 3+ messages in thread
From: Andrei Vagin @ 2016-05-12 0:10 UTC (permalink / raw)
To: LKML, Tejun Heo, Serge Hallyn
Hello,
https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=4f41fc59620fcedaa97cbdf3d7d2956d80fcd922
This commit breaks criu:
[root@fc22-vm criu]# ./criu/criu check
Error (mount.c:403): mnt: No root found for mountpoint 35 (@./sys/kernel/debug)
The problem is that mountinfo doesn't contain a /sys mount, so criu
can't build a tree of mounts.
[root@fc22-vm criu]# cat /proc/self/mountinfo | grep 17
20 17 0:18 / /sys/kernel/security rw,nosuid,nodev,noexec,relatime
shared:7 - securityfs securityfs rw
24 17 0:21 / /sys/fs/cgroup ro,nosuid,nodev,noexec shared:8 - tmpfs
tmpfs ro,mode=755
26 17 0:23 / /sys/fs/pstore rw,nosuid,nodev,noexec,relatime shared:18
- pstore pstore rw
34 24 0:31 / /sys/fs/cgroup/freezer rw,nosuid,nodev,noexec,relatime
shared:17 - cgroup cgroup rw,freezer
54 17 0:32 / /sys/kernel/config rw,relatime shared:19 - configfs configfs rw
35 17 0:7 / /sys/kernel/debug rw,relatime shared:22 - debugfs debugfs rw
[root@fc22-vm criu]# python
>>> import os
>>> os.open("/sys", os.O_RDONLY)
3
>>>
[1]+ Stopped python
[root@fc22-vm criu]# ps
PID TTY TIME CMD
760 pts/0 00:00:00 bash
913 pts/0 00:00:00 python
914 pts/0 00:00:00 ps
[root@fc22-vm criu]# cat /proc/913/fdinfo/3
pos: 0
flags: 0100000
mnt_id: 17
Thanks,
Andrew
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH] kernfs: kernfs_sop_show_path: don't return 0 after seq_dentry call
2016-05-12 0:10 cgroup, kernfs: make mountinfo show properly scoped path for cgroup namespaces Andrei Vagin
@ 2016-05-12 5:29 ` Serge E. Hallyn
2016-05-12 15:02 ` Tejun Heo
0 siblings, 1 reply; 3+ messages in thread
From: Serge E. Hallyn @ 2016-05-12 5:29 UTC (permalink / raw)
To: Andrei Vagin; +Cc: LKML, Tejun Heo, Serge Hallyn
Our caller expects 0 on success, not >0.
This fixes a bug in the patch
cgroup, kernfs: make mountinfo show properly scoped path for cgroup namespaces
where /sys does not show up in mountinfo, breaking criu.
Thanks for catching this, Andrei.
Reported-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
---
fs/kernfs/mount.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 3b78724..3d670a3 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -50,7 +50,8 @@ static int kernfs_sop_show_path(struct seq_file *sf, struct dentry *dentry)
if (scops && scops->show_path)
return scops->show_path(sf, node, root);
- return seq_dentry(sf, dentry, " \t\n\\");
+ seq_dentry(sf, dentry, " \t\n\\");
+ return 0;
}
const struct super_operations kernfs_sops = {
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] kernfs: kernfs_sop_show_path: don't return 0 after seq_dentry call
2016-05-12 5:29 ` [PATCH] kernfs: kernfs_sop_show_path: don't return 0 after seq_dentry call Serge E. Hallyn
@ 2016-05-12 15:02 ` Tejun Heo
0 siblings, 0 replies; 3+ messages in thread
From: Tejun Heo @ 2016-05-12 15:02 UTC (permalink / raw)
To: Serge E. Hallyn; +Cc: Andrei Vagin, LKML
On Thu, May 12, 2016 at 12:29:45AM -0500, Serge E. Hallyn wrote:
> Our caller expects 0 on success, not >0.
>
> This fixes a bug in the patch
>
> cgroup, kernfs: make mountinfo show properly scoped path for cgroup namespaces
>
> where /sys does not show up in mountinfo, breaking criu.
>
> Thanks for catching this, Andrei.
>
> Reported-by: Andrei Vagin <avagin@gmail.com>
> Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Applied to cgroup/for-4.6-fixes.
Thanks.
--
tejun
^ permalink raw reply [flat|nested] 3+ messages in thread
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2016-05-12 0:10 cgroup, kernfs: make mountinfo show properly scoped path for cgroup namespaces Andrei Vagin
2016-05-12 5:29 ` [PATCH] kernfs: kernfs_sop_show_path: don't return 0 after seq_dentry call Serge E. Hallyn
2016-05-12 15:02 ` Tejun Heo
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