[Bug 1781746] Re: [SRU] Slow startup with zram-config installed (/dev/zram0) or encrypted swap

[Brian Murray]

While it does appear to be a simple 3 line patch and may apply cleanly
the resume hook seems to have been modified heavily and the ephemeral
variable does not appear in the rest of the hook, so while it would be
set nothing would change with the behavior.

** Tags removed: rls-bb-incoming
** Tags added: rls-dd-incoming

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Title:
  [SRU] Slow startup with zram-config installed (/dev/zram0) or
  encrypted swap

Status in Default settings and artwork for Baltix OS:
  Confirmed
Status in initramfs-tools package in Ubuntu:
  Confirmed
Status in zram-config package in Ubuntu:
  Confirmed
Status in initramfs-tools package in Debian:
  Fix Released

Bug description:
  [Impact]

  Ubuntu 18.04 startup slowdowns for 30-120 seconds when zram swap is enabled (for example zram-config installed) or swap is encrypted.
  Today lots of users have SSD instead of HDD disk drives and use zram swap instead of swap partition or swap file, but if initrd is generated when zram swap is enabled then system can become "unbootable" from the user's perspective (Users with SSD storage doesn't wait 2 or more minutes...)

  This bug is already fixed in Debian initramfs-tools ver 0.132, please accept this simple 3 lines patch from Debian into Ubuntu 18.04 LTS
  https://salsa.debian.org/kernel-team/initramfs-tools/commit/312393b0cf1231125eeff3d1a2b6b778a935c21d

  [Test Case]
  Install zram-config package and regenerate and initrd, for example with 
  sudo update-initramfs -u

  When generating initrd I get this message in terminal:

  I: The initramfs will attempt to resume from /dev/zram0
  I: (UUID=e380356c-767e-4265-98da-8be62ad28569)
  I: Set the RESUME variable to override this.###########################################.................]

  So the local-premount script in initramfs was waiting for a swap
  device that was not available, until it timed out. The relevant
  message was gave up waiting for suspend/resume device.

  [Regression Potential]

  None, patch simply adds case for /dev/zram*:

  60	case "$resume_auto" in
  61	/dev/zram*)
  62		ephemeral=true
  63		;;
  64	esac

  
  [Other Info]
  Manual method to disable this (as resuming from swap is not possible with an encrypted or zram swap): modify file /etc/initramfs-tools/conf.d/resume - add (or change) line
  RESUME=none
  (instead of the UUID that was here) will disable waiting for a resume device.
  and run sudo update-initramfs -u to apply the changes.

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