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[Philipp Kern <pkern@xxxxxxxxxx>]

Sadly we need a second patch, after which it runs stable in my testing.
I'm not into the intrinsic details of x32, but apparently the syscalls
come in through both the 64bit and 32bit paths, which I find a bit
weird. (At least my first patch made it occur significantly less often.)

Patch attached this time. IS_IA32 is defined like this:

#elif defined CONFIG_IA32_EMULATION
# define IS_IA32        is_compat_task()

process_64.c says this about is_compat_task():

                /* is_compat_task() uses the presence of the x32
                   syscall bit flag to determine compat status */

And indeed:

static inline bool is_compat_task(void) 
{
        return is_ia32_task() || is_x32_task();
}

** Patch added: "ptrace.diff"
   https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1302605/+attachment/4120171/+files/ptrace.diff

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https://bugs.launchpad.net/bugs/1302605

Title:
  Calls to /libx32/ld-linux-x32.so.2 hang when using auditd

Status in “linux” package in Ubuntu:
  Confirmed
Status in “linux” source package in Trusty:
  New

Bug description:
  I'm running trusty on a bunch of machines, doing frequent dist-
  upgrades.  My hosts have gcc-multilib installed.

  Yesterday, I noticed that initramfs generation was hanging.  Today I
  investigated further and found out that what was hanging were the
  calls to /libx32/ld-linux-x32.so.2.

  This is triggered in initramfs generation because there are at some
  hooks that incorrectly use copy_exec to copy shell scripts into the
  initramfs image.  In a working machine, when ldd encounters a shell
  script, it will first call the 64bit linker and since it fails, it
  will then call the 32bit linker which will also fail.

  However, in a machine affected by this bug, the second call will hang
  forever, preventing new image generation, and package updates in
  general, when this happens as a trigger for update-initramfs.

  Originally I thought this was related to the kernel version, since I
  was unable to reproduce in a freshly installed machine running -22 and
  was reproducing it in a machine running -20, but now I'm also
  reproducing it in a machine running -22, so it must be something else.

  I'm sorry I can't provide the exact cause right now, but I think it's
  worth noting that in some situation there might be a problem, and try
  to find out which those situations are.

  I now have one host running 3.13.0-22-generic, with
  libc6-x32=2.19-0ubuntu3, where doing ldd /usr/bin/ldd hangs, and
  another host, with the exact same kernel and libc6-x32 version where
  doing ldd /usr/bin/ldd produces the expected error message (not a
  dynamic executable).  The main difference is that the first one was
  installed yesterday and the second one was installed today.  Both are
  dist-upgraded to the latest version of everything.

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