[lxc-devel] [PATCH 1/1] userns: clear and save id_map

[Serge Hallyn]

Quoting Dwight Engen (dwight.engen at oracle.com):
> Starting program: /usr/bin/lxc-clone -s -o ol64-01 -n ol64-04
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/lib64/libthread_db.so.1".
> Detaching after fork from child process 28359.
> Detaching after fork from child process 28361.
> 
> Program received signal SIGSEGV, Segmentation fault.
> 0x00007f99e689e08e in write_config (fout=fout at entry=0x1b79670, c=0x1b77400)
>     at confile.c:1950
> 1950	confile.c: No such file or directory.
> Missing separate debuginfos, use: debuginfo-install lxc-0.9.x-1.fc18.x86_64
> (gdb) bt
> #0  0x00007f99e689e08e in write_config (fout=fout at entry=0x1b79670, c=0x1b77400)
>     at confile.c:1950
> #1  0x00007f99e68a6c6b in lxcapi_save_config (c=0x1b764d0, alt_file=<optimized out>)
>     at lxccontainer.c:1214
> #2  0x00007f99e68a99b8 in lxcapi_clone (c=<optimized out>, newname=<optimized out>, 
>     lxcpath=<optimized out>, flags=<optimized out>, bdevtype=0x0, bdevdata=0x0, 
>     newsize=0, hookargs=0x0) at lxccontainer.c:1963
> #3  0x0000000000400d2f in main ()

Actually I think that looks a bit different from the segfault I was
getting with my first version - please let me know if v2 still
causes this for you.  (I don't get it with non-snapped clones).

The reason I needed this patch now was because with unprivileged
lxc-create, the container config with id map gets saved and restored
a few times during the course of container creation, so losing the
id mapping was a blocker :)

Hoping to send some fun patches soon.

-serge