[CRIU] two runc related questions (-d and read-only)

[Marcos Lilljedahl]

On Fri, Sep 16, 2016 at 1:46 PM, Andrei Vagin <avagin at virtuozzo.com> wrote:

> On Wed, Sep 14, 2016 at 05:06:15PM +0200, Adrian Reber wrote:
> > On Wed, Sep 14, 2016 at 05:45:49AM -0700, Andrei Vagin wrote:
> > > On Mon, Sep 12, 2016 at 07:41:29PM +0200, Adrian Reber wrote:
> > > > I was trying to checkpoint and restore a runc container and so far I
> had
> > > > two smaller problems. My runc container has
> > > >
> > > >   "terminal": false
> > > >
> > > > and I am starting it detached '-d'. Checkpointing this container
> fails
> > > > if I run 'runc checkpoint --shell-job test' or without '--shell-job'
> > > > with following error:
> > > >
> > > > (00.003008) 29213 fdinfo 0: pos: 0x               0 flags: 102002/0
> > > > (00.003022) tty: Dumping tty 8 with id 0x7
> > > > (00.003026) Error (files-reg.c:1141): Can't lookup mount=22 for fd=0
> path=/dev/pts/2
> > > > (00.003029) ----------------------------------------
> > > > (00.003071) Error (cr-dump.c:1296): Dump files (pid: 29213) failed
> with -1
> > > >
> > > > I get the same error using criu-2.4 and latest master. If I start the
> > > > container without '-d' I can checkpoint it without any problem.
> > >
> > > Could you try to run ./runc ... &> /dev/null  < /dev/null? Will it
> help?
> >
> > Yes, that works.
> >
> > > Could you show lsof -p for an init process of a container?
> >
> > This is without the /dev/null redirection you suggested:
> >
> > COMMAND  PID USER   FD   TYPE DEVICE SIZE/OFF      NODE NAME
> > start   7464 root  cwd    DIR  252,1     4096   9129255 /
> > start   7464 root  rtd    DIR  252,1     4096   9129255 /
> > start   7464 root  txt    REG  252,1   960376 192967906 /usr/bin/bash
> > start   7464 root  mem    REG  252,1          193825299 /usr/lib64/
> libnss_files-2.17.so (path inode=16885464)
> > start   7464 root  mem    REG  252,1          193773498 /usr/lib64/
> libc-2.17.so (path inode=16883722)
> > start   7464 root  mem    REG  252,1          193825248 /usr/lib64/
> libdl-2.17.so (path inode=16884707)
> > start   7464 root  mem    REG  252,1          193825325
> /usr/lib64/libtinfo.so.5.9 (path inode=16860633)
> > start   7464 root  mem    REG  252,1          193773472 /usr/lib64/
> ld-2.17.so (path inode=16820578)
> > start   7464 root    0u   CHR  136,2      0t0         5 /dev/pts/2
> > start   7464 root    1u   CHR  136,2      0t0         5 /dev/pts/2
> > start   7464 root    2u   CHR  136,2      0t0         5 /dev/pts/2
> > start   7464 root  255r   REG  252,1       83   8550670 /start
> >
> >
> > > > Another problem I have seen is using runc with
> > > >
> > > >   "readonly": true
> > > >
> > > > this gives me following error:
> > > >
> > > > (00.079785) Dumping task cwd id 0xb root id 0xb
> > > > (00.079931) mnt: Dumping mountpoints
> > > > (00.079934) mnt:  213: 2b:/null @ ./proc/sched_debug
> > > > (00.079934) mnt: Something is mounted on top of ./dev
> > > > (00.080004) Error (criu/mount.c:1044): mnt: Can't create a temporary
> directory: Read-only file system
> > >
> > > It's known issue. Yesterday I started to rework mount.c to support this
> > > case. I will try to prepare draft patches before Friday.
> >
> > Great, good to know.
>
> I pushed my changes on github, but I don't test them with runc.
> https://github.com/avagin/criu/commits/mntns_for_adrian


I can give it a try and let u know how it goes Andrei.


>
>
> >
> >               Adrian
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