[CRIU] link_remap_ok

Fri Feb 27 12:09:57 PST 2015

Is this ok?

/sdcard # lxc-attach -n L -- cat /proc/self/mountinfo
16 16 0:2 / / rw - rootfs rootfs rw,size=372900k,nr_inodes=93225
17 16 0:4 / /proc rw,relatime - proc proc rw
18 16 0:11 / /sys rw,relatime - sysfs sysfs rw
19 18 0:12 / /sys/fs/cgroup rw,relatime - cgroup none
rw,cpuset,debug,cpu,cpuacct,memory,devices,freezer,blkio,perf_event,clone_children
20 18 0:6 / /sys/kernel/debug rw,relatime - debugfs none rw
21 16 0:10 / /dev/pts rw,relatime - devpts devpts rw,mode=600,ptmxmode=000
22 16 179:0 / /sdcard rw,relatime - ext2 /dev/mmcblk0 rw
24 16 0:2 /usr/local/lib/lxc/rootfs /usr/local/lib/lxc/rootfs rw - rootfs
rootfs rw,size=372900k,nr_inodes=93225
25 24 0:14 / /usr/local/lib/lxc/rootfs rw,relatime - tmpfs none
rw,size=12k,mode=755
35 25 179:0 /L/rootfs /usr/local/lib/lxc/rootfs/root rw,relatime shared:1 -
ext2 /dev/mmcblk0 rw
36 35 0:13 / /usr/local/lib/lxc/rootfs/root/proc rw,relatime shared:2 -
proc none rw
37 35 0:15 / /usr/local/lib/lxc/rootfs/root/sys rw,relatime shared:3 -
sysfs none rw
38 35 0:2 /dev /usr/local/lib/lxc/rootfs/root/dev rw,relatime shared:6 -
rootfs rootfs rw,size=372900k,nr_inodes=93225
39 38 0:10 /1 /usr/local/lib/lxc/rootfs/root/dev/console rw,relatime
shared:7 - devpts devpts rw,mode=600,ptmxmode=000
26 37 0:6 / /usr/local/lib/lxc/rootfs/root/sys/kernel/debug rw,relatime
shared:4 - debugfs debugfs rw
27 37 0:16 / /usr/local/lib/lxc/rootfs/root/sys/fs/cgroup rw,relatime
shared:5 - tmpfs none rw,mode=750,gid=1000
28 35 0:17 / /usr/local/lib/lxc/rootfs/root/mnt/asec rw,relatime shared:8 -
tmpfs tmpfs rw,mode=755,gid=1000
29 35 0:18 / /usr/local/lib/lxc/rootfs/root/mnt/obb rw,relatime shared:9 -
tmpfs tmpfs rw,mode=755,gid=1000
30 35 31:0 / /usr/local/lib/lxc/rootfs/root/system ro,relatime shared:10 -
ext4 /dev/block/mtdblock0 ro,data=ordered
31 35 31:1 / /usr/local/lib/lxc/rootfs/root/data rw,nosuid,nodev,noatime
shared:11 - ext4 /dev/block/mtdblock1 rw,data=ordered
32 35 31:2 / /usr/local/lib/lxc/rootfs/root/cache rw,nosuid,nodev,noatime
shared:12 - ext4 /dev/block/mtdblock2 rw,data=ordered

/sdcard # cat /proc/self/mountinfo
1 1 0:2 / / rw - rootfs rootfs rw,size=372900k,nr_inodes=93225
10 1 0:4 / /proc rw,relatime - proc proc rw
11 1 0:11 / /sys rw,relatime - sysfs sysfs rw
12 11 0:12 / /sys/fs/cgroup rw,relatime - cgroup none
rw,cpuset,debug,cpu,cpuacct,memory,devices,freezer,blkio,perf_event,clone_children
13 11 0:6 / /sys/kernel/debug rw,relatime - debugfs none rw
14 1 0:10 / /dev/pts rw,relatime - devpts devpts rw,mode=600,ptmxmode=000
15 1 179:0 / /sdcard rw,relatime - ext2 /dev/mmcblk0 rw
/sdcard #

I have this line in my lxc.conf
lxc.mount.entry=/dev /sdcard/L/rootfs/dev none defaults,bind 0 0

Thanks.

On Sat, Feb 28, 2015 at 1:20 AM, Pavel Emelyanov <xemul at parallels.com>
wrote:

> On 02/27/2015 08:05 PM, beproject criu wrote:
> > path [/usr/local/lib/lxc/rootfs/root] read_fd_link() return : 30
> > I have mounted the /dev of host on /dev inside my container.
>
> That's interesting. How did you do it? Can you show me the mount namespaces
> layout on your node and inside the container? It's just
> /proc/$pid/mountinfo
> file contents on some process on host and some process in CT.
>
> > (03.347637) Dumping path for 4 fd via self 43
> [/usr/local/lib/lxc/rootfs/root/dev/__properties__]
>
> OK, this is quite strange. The /usr/local/lib/lxc/rootfs is the path on
> HOST.
> How did this path become visible inside container?
>
> > (03.347847) [nyc_fd] The required root is already opened.
> get_service_fd() returns : 1017
> > (03.348197) [nyc_fd] Going into fstatat()-> [mntns_root : 1017],[rpath :
> ./usr/local/lib/lxc/rootfs/root/dev/__properties__]
> > (03.348393) [nyc_fd] Out of fstatat()-> [ret : -1],[rpath :
> ./usr/local/lib/lxc/rootfs/root/dev/__properties__]
> > (03.348583) [nyc_fd] Going into dump_linked_remap()
> > (03.349177) [nyc_fd] The required root is already opened.
> get_service_fd() returns : 1017
> > (03.349432) [nyc_fd] Doing linkat() [mntns_root : 1017],[link_name :
> ./usr/local/lib/lxc/rootfs/root/dev/link_remap.4]
> >
> > (03.349756) [nyc_fd] bad_path [/usr/local/lib/lxc/rootfs/root]
> ,read_fd_link() return : 30
> >
> > (03.350027) Error (files-reg.c:515): Can't link remap to
> /usr/local/lib/lxc/rootfs/root/dev/__properties__: No such file or directory
> > (03.351097) [nyc_fd] Error in dump_one_reg_file->check_path_remap()
> > (03.351266) [nyc_fd] Going into dump_task_files_seized() :
> dump_one_file()
> >
> >
> > On Fri, Feb 27, 2015 at 8:10 PM, Pavel Emelyanov <xemul at parallels.com
> <mailto:xemul at parallels.com>> wrote:
> >
> >     On 02/27/2015 05:25 PM, beproject criu wrote:
> >     > This is the flow before error,could you get what's wrong :
> >     >
> >     > (02.352922) Dumping path for 4 fd via self 43
> [/usr/local/lib/lxc/rootfs/root/dev/__properties__]
> >     > (02.353079) [nyc_fd] The required root is already opened.
> get_service_fd() returns : 1017
> >     > (02.353216) [nyc_fd] Going into fstatat()-> [mntns_root :
> 1017],[rpath : ./usr/local/lib/lxc/rootfs/root/dev/__properties__]
> >     > (02.353398) [nyc_fd] Out of fstatat()-> [ret : -1],[rpath :
> ./usr/local/lib/lxc/rootfs/root/dev/__properties__]
> >     > (02.353574) [nyc_fd] Going into dump_linked_remap()
> >     > (02.354191) [nyc_fd] The required root is already opened.
> get_service_fd() returns : 1017
> >     > (02.354431) [nyc_fd] Doing linkat() [mntns_root : 1017],[link_name
> : ./usr/local/lib/lxc/rootfs/root/dev/link_remap.4]
> >     > (02.354747) Error (files-reg.c:510): Can't link remap to
> /usr/local/lib/lxc/rootfs/root/dev/__properties__: No such file or directory
> >     > (02.355915) [nyc_fd] Error in dump_one_reg_file->check_path_remap()
> >     > (02.356066) [nyc_fd] Going into dump_task_files_seized() :
> dump_one_file()
> >
> >     OK, so in both cases we access file af fd 1017 and sub-path
> "./user/local/lib/lxc/roootfs/root/dev/__properties__"
> >     and you tell that this file actually exists in container, right?
> >
> >     The failing fstatat then means, that the 1017 descriptor points to
> some bad path. Can you check where? We
> >     have a helper called read_fd_link() helper for that, see the
> fsnotify.c line 455 for code example.
> >
> >     And one more question -- does your container live in another mount
> namespace, or shared one with host?
> >
> >     Thanks,
> >     Pavel
> >
> >
>
>
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