[Bug 1551828] Re: kpartx causes kernel oops when NVMe devices is not in blacklist

[Brian Murray]

Hello Ivan, or anyone else affected,

Accepted multipath-tools into trusty-proposed. The package will build
now and be available at https://launchpad.net/ubuntu/+source/multipath-
tools/0.4.9-3ubuntu7.10 in a few hours, and then in the -proposed
repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to
enable and use -proposed.  Your feedback will aid us getting this update
out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested, and change the tag
from verification-needed to verification-done. If it does not fix the
bug for you, please add a comment stating that, and change the tag to
verification-failed.  In either case, details of your testing will help
us make a better decision.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance!

** Changed in: multipath-tools (Ubuntu Trusty)
       Status: Triaged => Fix Committed

** Tags added: verification-needed

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https://bugs.launchpad.net/bugs/1551828

Title:
  kpartx causes kernel oops when NVMe devices is not in blacklist

Status in multipath-tools package in Ubuntu:
  Fix Released
Status in multipath-tools source package in Trusty:
  Fix Committed

Bug description:
  [Impact]
  Users expecting to use multipath over NVMe device will notice hangs with any software attempting to use the device-mapper devices (/dev/dm-* or /dev/mapper/mpath*).

  [Test case]
  1) Setup multipath over nvme. (should not be possible with the patch in)
  2) Run kpartx -av /dev/dm-device-mulipath-over-nvme   (will hang without the patch)

  [Regression Potential]
  Minimal. This removes a theoretically valid use case of multipath devices using NVMe disks, which is not technically supported and leads to software hangs (and thus installs will not complete, and setting up multipath over NVMe post-install would hang).
  This only affects nvme devices; so any storage device using the "nvme" naming would no longer be able to setup multipath even if technical specifications were to change sufficiently to support multipath over NVMe (or if some other device starts using this naming which isn't affected by the same limitations).

  
  -----

  When on bare metal uses NVMe devices - kpartx cause kernel oops.
  http://paste.openstack.org/show/488638/

  Also any tools which works with disks (e.g. fdisk, lsblk) hangs in D state (uninterruptible sleep) while trying to to read /dev/dm-X.
  This bug is already described and fixed in upstream (http://git.opensvc.com/gitweb.cgi?p=multipath-tools/.git;a=commitdiff;h=5c412e47e589b5325ed7de6cba86d906a671d9df)

  I made patches for trusty and xenial versions of multipath-tools.
  Patches which fix issue is in attach.
  Could you apply this patches please, at least for trusty version?

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