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

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You have been subscribed to a public bug by Mantas Kriaučiūnas (mantas):

[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.

** Affects: baltix-default-settings
     Importance: High
     Assignee: Mantas Kriaučiūnas (mantas)
         Status: Confirmed

** Affects: initramfs-tools (Ubuntu)
     Importance: Undecided
         Status: Confirmed

** Affects: zram-config (Ubuntu)
     Importance: Undecided
         Status: Confirmed

** Affects: initramfs-tools (Debian)
     Importance: Unknown
         Status: Fix Released


** Tags: bionic patch patch-accepted-debian
-- 
[SRU] Slow startup with zram-config installed (/dev/zram0) or encrypted swap
https://bugs.launchpad.net/bugs/1781746
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