[Bugme-new] [Bug 17281] New: [lxc] gdb cannot debug bash properly in an LXC container

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=17281

           Summary: [lxc] gdb cannot debug bash properly in an LXC
                    container
           Product: Process Management
           Version: 2.5
    Kernel Version: 2.6.33.7
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Other
        AssignedTo: process_other at kernel-bugs.osdl.org
        ReportedBy: greenrd at greenrd.org
                CC: lizf at cn.fujitsu.com, menage at google.com
        Regression: Yes


(I couldn't find a kernel bugzilla component for LXC bugs, so I picked
something that sounded vaguely related.)

gdb is unable to debug bash once the command "ls" is typed in, but only inside
an LXC container (outside the container, it works). The error message from gdb
is:

Couldn't write debug register: No such process

Steps to Reproduce:
1. Set up an LXC chroot containing gdb and bash (on Fedora Linux, this can be
done fairly easily by installing and configuring mach and then using "mach yum
install gdb bash". mach also supports apt-get.) I also installed the separate
-debuginfo packages inside the container, but I don't think this matters.
2. I use the libvirt command-line tools to actually start the LXC container,
because I couldn't manage to get the LXC userspace tools to create a container.
Define the LXC chroot in virsh, e.g. virsh define foo.xml for some libvirt
configuration file foo.xml
3. virsh --connect lxc:/// start foo && virsh --connect lxc:/// console foo
4. export PATH=/usr/bin:$PATH
5. gdb /bin/bash
6. Type 'r' to run bash
7. Inside that bash process, type 'ls' and hit the enter key

At this point it says 
Couldn't write debug register: No such process

FYI, I get a slightly different error message if I use the Fedora kernel
instead of the mainline kernel:
Waiting for child: no such process

Regarding the regression flag: I am *guessing* this is a regression, because
the very similar bug that I just mentioned in the Fedora kernel tree is
definitely a regression. I plan to test older and newer mainline kernel
versions at a later date.

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