this patch appears to fix it, i will try to build a kernel to test it https://git.kernel.org/cgit/linux/kernel/git/luto/linux.git/commit/?h=userns/fix_magic_nodev&id=bf8b198add82a249d6da4ecf280c30a0865637f6 http://www.spinics.net/lists/linux-containers/msg30469.html stable@ has been CC'ed, i don't know if it was applied -- 1AE0 322E B8F7 4717 BDEA BF1D 44BB 1BA7 9F6C 6333