[CRIU] Questions in CRIU restore mechanism.

[Cyrill Gorcunov]

On Sun, Mar 31, 2013 at 03:05:19PM +0900, Chanho Park wrote:
> > I tried to dump our simple 'clock' application.
> > I've got below error during the dump process.
> > How do we deal with the process which has shmem?
> > 
> > (00.042692) Found anon-shmem piggie at 4
> > (00.044305) Error (proc_parse.c:310): Can't handle non-regular mapping on
> > 3850's map 2920849408
> > (00.044417) Error (cr-dump.c:1367): Collect mappings (pid: 3850) failed
> > with -1
> > 
> 
> This error was caused due to /dev/ump and /dev/mali device node which are related with mali gpu device.
> So, I passed it temporarily.
> 
> The next error was produced by /dev/console.
> 
> Parasite cmd 11/0xb process
> (00.310244) 3610 fdinfo 0: pos: 0x               0 flags:           400000/0
> (00.310466) Dumping path for 0 fd via self 759 [/dev/null]
> (00.310609) fdinfo: type: 0x 1 flags: 0400000/0 pos: 0x       0 fd: 0
> (00.310684) 3610 fdinfo 1: pos: 0x        ffffffff flags:                2/0
> (00.310743) tty: Dumping tty 760 with id 0x2
> (00.310811) Error (tty.c:203): tty: Can't obtain ptmx index: Inappropriate ioctl for device
> (00.310933) ----------------------------------------
> (00.310962) Error (cr-dump.c:1419): Dump files (pid: 3610) failed with -1
> 
> The serial node can't supports GIOCGPTN ioctl.
> I think only unix-ptmx node will support it.
> How about you think this problem?

Hmm, two ways I think of

 - implement support for c/r for this devices (which might require kernel
   patching)

 - skip c/r of this devices if they are not important for process, which I
   really doubt of.

Thus I guess most probably you've to add c/r support for them (or close
this files before c/r starts thus crtools won't collect this file descriptors).

> 
> There are also some problem to dump character devices.
> dump_chrdev supports only MEM_MAJOR and TTY types.
> To dump any other character device types, we need to implement for that device. Right?

Exactly.