port-xen/54273: "zpool create pool xbd2" panics DOMU kernel

[jarle%norid.no@localhost]

>Number:         54273
>Category:       port-xen
>Synopsis:       "zpool create pool xbd2" panics DOMU kernel
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-xen-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Jun 05 17:20:00 +0000 2019
>Originator:     Jarle Fredrik Greipsland
>Release:        NetBSD 8.99.42 from 2019-06-03
>Organization:
	
>Environment:
	
	
System: NetBSD vm-2129 8.99.42 NetBSD 8.99.42 (XEN3_DOMU) #2: Tue Jun  4 09:31:29 CEST 2019  jarle@nbuilder:/build/current/amd64/obj/sys/arch/amd64/compile/XEN3_DOMU amd64
Architecture: x86_64
Machine: amd64
>Description:

A VM configured with xbd0 and xbd1 as root and swap, and then with
xbd2, xbd3 and xbd4 as separate block devices for zfs experimentation.
All the xbd* devices are freshly created logical volumes in an lvm
volume group on the hypervisor.

zfs has not previously been configured on this VM.  I ran the command:

vm-2129# zpool create pool xbd2

in an xterm window, and then on the console, the following panic
message was printed:

[ 274.4901995] panic: kernel diagnostic assertion "seg <= BLKIF_MAX_SEGMENTS_PER_REQUEST" failed: file "/build/current/src/sys/arch/xen/xen/xbd_xenbus.c", line 1032 
[ 274.4901995] cpu0: Begin traceback...
[ 274.4901995] vpanic() at netbsd:vpanic+0x143
[ 274.4901995] kern_assert() at netbsd:kern_assert+0x48
[ 274.4901995] xbd_diskstart() at netbsd:xbd_diskstart+0x3c7
[ 274.4901995] dk_start() at netbsd:dk_start+0xd9
[ 274.4901995] bdev_strategy() at netbsd:bdev_strategy+0x72
[ 274.4901995] spec_strategy() at netbsd:spec_strategy+0x96
[ 274.4901995] VOP_STRATEGY() at netbsd:VOP_STRATEGY+0x54
[ 274.4901995] vdev_disk_io_start() at zfs:vdev_disk_io_start+0x124
[ 274.4901995] zio_vdev_io_start() at zfs:zio_vdev_io_start+0x12e
[ 274.4901995] zio_execute() at zfs:zio_execute+0xb0
[ 274.4901995] zio_nowait() at zfs:zio_nowait+0x5c
[ 274.4901995] vdev_label_read_config() at zfs:vdev_label_read_config+0xc8
[ 274.4901995] vdev_label_init() at zfs:vdev_label_init+0x4cc
[ 274.4901995] vdev_label_init() at zfs:vdev_label_init+0x47
[ 274.4901995] vdev_create() at zfs:vdev_create+0x5a
[ 274.5001272] spa_create() at zfs:spa_create+0x28c
[ 274.5001272] zfs_ioc_pool_create() at zfs:zfs_ioc_pool_create+0x19b
[ 274.5001272] zfsdev_ioctl() at zfs:zfsdev_ioctl+0x265
[ 274.5001272] nb_zfsdev_ioctl() at zfs:nb_zfsdev_ioctl+0x38
[ 274.5001272] VOP_IOCTL() at netbsd:VOP_IOCTL+0x3b
[ 274.5001272] vn_ioctl() at netbsd:vn_ioctl+0xa5
[ 274.5001272] sys_ioctl() at netbsd:sys_ioctl+0x547
[ 274.5001272] syscall() at netbsd:syscall+0x9c
[ 274.5001272] --- syscall (number 54) ---
[ 274.5001272] 7b61eb79534a:
[ 274.5001272] cpu0: End traceback...

[ 274.5001272] dumping to dev 142,17 (offset=4194303, size=0): not possible
[ 274.5001272] rebooting...

and the VM rebooted.

	
>How-To-Repeat:
	
>Fix:
	

>Unformatted: