kernel-packages team mailing list archive

[James Page <james.page@xxxxxxxxxx>]

Public bug reported:

We're doing some testing of bcache to see how it improves block
performance in trusty; right now we're hitting a problem where processes
performing filesystem operations get hung on the default 3.13 kernel:

 [ 7083.029073] INFO: task qemu-img:96548 blocked for more than 120 seconds.
 [ 7083.035797]       Not tainted 3.13.0-45-generic #74-Ubuntu
 [ 7083.041325] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

we don't see the same issue if we switch to the 3.16 hwe kernel.

Fairly easy to reproduce so can try test kernels - will also try to get
a bit more debug for you on this one.

** Affects: linux (Ubuntu)
     Importance: Undecided
         Status: Incomplete


** Tags: trusty

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https://bugs.launchpad.net/bugs/1425128

Title:
  bcache causes task hang with 3.13 kernel

Status in linux package in Ubuntu:
  Incomplete

Bug description:
  We're doing some testing of bcache to see how it improves block
  performance in trusty; right now we're hitting a problem where
  processes performing filesystem operations get hung on the default
  3.13 kernel:

   [ 7083.029073] INFO: task qemu-img:96548 blocked for more than 120 seconds.
   [ 7083.035797]       Not tainted 3.13.0-45-generic #74-Ubuntu
   [ 7083.041325] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

  we don't see the same issue if we switch to the 3.16 hwe kernel.

  Fairly easy to reproduce so can try test kernels - will also try to
  get a bit more debug for you on this one.

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