[Bug 922754] Re: booting without --no-log causes init and plymouth-upstart-bridge to spin at 100%

[Jason Conti]

I am seeing similar activity when I attempt to reboot over ssh. The
system boots fine and I don't see any high cpu activity from init
otherwise. The system will not reboot until I exit the ssh session. This
only appears to happen over ssh, it reboots fine otherwise.

Strace on pid 1 yields an endless stream of:
read(11, 0x7f7d8d703730, 8192)          = -1 EAGAIN (Resource temporarily unavailable)

With /proc/1/fd/11:
lrwx------ 1 root root 64 Jan 27 15:53 /proc/1/fd/11 -> /dev/ptmx

Which seems to match above. This is on real hardware and here is /proc/cmdline:
BOOT_IMAGE=/boot/vmlinuz-3.2.0-11-generic root=UUID=16258cc4-9dec-421a-9f8e-c0e6632dda7d ro quiet splash vt.handoff=7

The disabled logging in 1.4-0ubuntu4 appears to fix this though, the
system reboots immediately without having to exit the ssh session first.

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Title:
  booting without --no-log causes init and plymouth-upstart-bridge to
  spin at 100%

Status in “upstart” package in Ubuntu:
  Incomplete

Bug description:
  Release: Precise
  Architecture: amd64

  Likely broken since upstart_1.4-0ubuntu3

  When booting after recent updates I see init and plymouth-upstart-
  bridge spinning at 100% CPU time, defunct processes do not get reaped
  and a console on ttyS1 which is supposed to start, does not come up.

  Looking at strace of plymouth-upstart-bridge it seems to run a tight loop of 
  epoll_wait(3, {}, 64, 0)                = 0 (/proc/1383/fd/3 -> anon_inode:[eventpoll])

  and init does another tight loop of
  read(24, 0x7ffdc2d1caa0, 8192)          = -1 EAGAIN (Resource temporarily unavailable)
    (/proc/1/fd/24 -> /dev/ptmx)

  Booting with --no-log on the grub commandline brings the system up
  without showing any problems.

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