diff -Nru cryptsetup-1.6.6/debian/changelog cryptsetup-1.6.6/debian/changelog
--- cryptsetup-1.6.6/debian/changelog	2015-08-21 00:59:11.000000000 -0700
+++ cryptsetup-1.6.6/debian/changelog	2015-12-02 21:59:45.000000000 -0800
@@ -1,3 +1,12 @@
+cryptsetup (2:1.6.6-5ubuntu3) UNRELEASED; urgency=medium
+
+  * debian/initramfs/cryptroot-script: don't call vgchange, which udev rules
+    already handle for us.  Instead we should be calling udevadm settle at
+    the right points to ensure devices are visible before we try to use
+    them.  Thanks to Richard Hansen for the analysis.  LP: #1481536.
+
+ -- Steve Langasek <steve.langasek@ubuntu.com>  Wed, 02 Dec 2015 21:20:13 -0800
+
 cryptsetup (2:1.6.6-5ubuntu2) wily; urgency=medium
 
   * Fix stupid typo in Recommends "busybox | busybox-static" inversion.
diff -Nru cryptsetup-1.6.6/debian/initramfs/cryptroot-script cryptsetup-1.6.6/debian/initramfs/cryptroot-script
--- cryptsetup-1.6.6/debian/initramfs/cryptroot-script	2015-03-28 13:38:34.000000000 -0700
+++ cryptsetup-1.6.6/debian/initramfs/cryptroot-script	2015-12-02 21:58:40.000000000 -0800
@@ -155,20 +155,6 @@
 	return 0
 }
 
-activate_vg()
-{
-	# Sanity checks
-	if [ ! -x /sbin/lvm ]; then
-		message "cryptsetup: lvm is not available"
-		return 1
-	fi
-
-	# Detect and activate available volume groups
-	/sbin/lvm vgscan
-	/sbin/lvm vgchange -a y --sysinit
-	return $?
-}
-
 setup_mapping()
 {
 	local opts count cryptopen cryptremove NEWROOT
@@ -199,9 +185,7 @@
 	modprobe -q dm_crypt
 
 	# Make sure the cryptsource device is available
-	if [ ! -e $cryptsource ]; then
-		activate_vg
-	fi
+	udev_settle
 
 	# If the encrypted source device hasn't shown up yet, give it a
 	# little while to deal with removable devices
@@ -213,18 +197,21 @@
 		log_begin_msg "Waiting for encrypted source device..."
 
 		# Default delay is 180s
-		if [ -z "${ROOTDELAY}" ]; then
-			slumber=180
-		else
-			slumber=${ROOTDELAY}
-		fi
+		slumber=${ROOTDELAY:-180}
 
 		slumber=$(( ${slumber} * 10 ))
 		while [ ! -e "$cryptsource" ]; do
-			# retry for LVM devices every 10 seconds
-			if [ ${slumber} -eq $(( ${slumber}/100*100 )) ]; then
-				activate_vg
-			fi
+			# Each call to udev_settle can block for up to 30
+			# seconds, so the worst case scenario here is a boot
+			# delay of $ROOTDELAY*10*30 seconds = 15 hours.
+			# However, this could only ever happen if udev
+			# constantly had new events being queued *and* none of
+			# these events resulted in the root device becoming
+			# available.  Still, a more correct solution would
+			# measure against wall time and call udevadm settle
+			# in a loop until the $ROOTDELAY timeout has been
+			# reached.
+			udev_settle
 
 			/bin/sleep 0.1
 			slumber=$(( ${slumber} - 1 ))
@@ -237,7 +224,6 @@
 			log_end_msg 1 || true
 		fi
  	fi
-	udev_settle
 
 	# We've given up, but we'll let the user fix matters if they can
 	if [ ! -e "${cryptsource}" ]; then
@@ -319,11 +305,8 @@
 			if [ -z "$cryptlvm" ]; then
 				message "cryptsetup: lvm fs found but no lvm configured"
 				return 1
-			elif ! activate_vg; then
-				# disable error message, LP: #151532
-				#message "cryptsetup: failed to setup lvm device"
-				return 1
 			fi
+			udev_settle
 
 			# Apparently ROOT is already set in /conf/param.conf for
 			# flashed kernels at least. See bugreport #759720.
@@ -343,7 +326,6 @@
 		#if [ -z "$FSTYPE" ] || [ "$FSTYPE" = "unknown" ]; then
 		if [ -z "$FSTYPE" ]; then
 			message "cryptsetup: unknown fstype, bad password or options?"
-			udev_settle
 			$cryptremove
 			continue
 		fi