Re: [v3][PATCH 5/5] Merge code for single and multiple-instance mounts

Eric Paris
2009-05-07T22:36:20Z

On Thu, 2009-05-07 at 14:24 -0700, Sukadev Bhattiprolu wrote:
> Eric Paris [eparis@parisplace.org] wrote:
> | On Sat, Mar 7, 2009 at 2:12 PM, Sukadev Bhattiprolu
> | <sukadev@linux.vnet.ibm.com> wrote:
> | >
> | > From: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
> | > Subject: [v3][PATCH 5/5] Merge code for single and multiple-instance mounts
> |
> | I just tried to load the linux-next kernel on F11 and ran into a
> | problem. X started, I could log in, I could start programs like
> | firefox and evolution, but not gnome-terminal. It would just flash
> | and disappear. Running xterm resulted in a window, that I could type
> | in, but it wasn't a shell. It didn't do anything.
> |
> | I switched to vt2 set the display to my X session and tried to run
> | xterm. It said something about a permission being denied, so I
> | decided to strace it. I saw EACCESS returning from calls dealing with
> | /dev/pts/0. This lead me to git bisect start fs/devpts from the
> | latest in linux-next as bad and 2.6.29 as good. Couple interations
> | later and I find that this commit (1bd7903560f1f7) breaks
> | gnome-terminal xterm!
>
> Interesting :-) -EACCESS makes me suspect that maybe 'mode' 'uid' or 'gid'
> mount options are wrong. Of course we would still need to understand if/
> why this patch changes the settings.
>
> Can you paste the output of following commands: (both in success and failure
> cases).
>
> $ grep devpts /proc/mounts

Success: devpts /dev/pts devpts rw,relatime,mode=600,ptmxmode=000 0 0
Failure: devpts /dev/pts devpts rw,seclabel,relatime,mode=000,ptmxmode=000 0 0

> $ ls -al /dev/pts
Success:
[root@dhcp231-142 ~]# ls -al /dev/pts
total 0
drwxr-xr-x. 2 root root 0 2009-05-07 16:04 .
drwxr-xr-x. 20 root root 5300 2009-05-07 18:13 ..
crw--w----. 1 paris paris 136, 0 2009-05-07 18:17 0
crw--w----. 1 paris paris 136, 1 2009-05-07 16:07 1
crw--w----. 1 paris paris 136, 2 2009-05-07 18:13 2
crw--w----. 1 paris paris 136, 3 2009-05-07 18:17 3
c---------. 1 root root 5, 2 2009-05-07 16:04 ptmx

Failure:
[root@dhcp231-142 ~]# ls -al /dev/pts
total 0
drwxr-xr-x. 2 root root 0 2009-05-07 18:22 .
drwxr-xr-x. 20 root root 5460 2009-05-07 18:28 ..
c---------. 1 root root 5, 2 2009-05-07 18:22 ptmx

> $ stat /dev/ptmx

Failure:
File: `/dev/ptmx'
Size: 0 Blocks: 0 IO Block: 4096 character special file
Device: eh/14d Inode: 704 Links: 1 Device type: 5,2
Access: (0666/crw-rw-rw-) Uid: ( 0/ root) Gid: ( 5/ tty)
Access: 2009-05-07 18:23:20.695621624 -0400
Modify: 2009-05-07 18:22:25.460004885 -0400
Change: 2009-05-07 18:22:31.911129737 -0400

>
> Also, is CONFIG_DEVPTS_MULTIPLE_INSTANCES set in your .config ?

CONFIG_DEVPTS_MULTIPLE_INSTANCES=y

> With this patch, does gnome-terminal run when logged in as root ?

gnome-terminal did not, but xterm did appear in my window as root. I
assumed it was just some gnomism to not let me launch a root
gnome-terminal inside the user owned X session.

I unmounted /dev/pts and remounted it with mode=600 and it works now!

So something about this patch caused it to change from being mounted 600
to 000.....