kern/162008: [zfs] Latest 9-STABLE and 10-CURRENT fail to boot from ZFS v15 root

[Robert Millan]

>Number:         162008
>Category:       kern
>Synopsis:       [zfs] Latest 9-STABLE and 10-CURRENT fail to boot from ZFS v15 root
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Oct 25 17:00:19 UTC 2011
>Closed-Date:
>Last-Modified:
>Originator:     Robert Millan
>Release:        Debian GNU/kFreeBSD "sid"
>Organization:
>Environment:
see description
>Description:
With both 9-STABLE and 10-CURRENT, since recently the kernel is no longer able to boot from my ZFS pool as root file system.

The on-disk pool is ZFS version 15 and was created with 8.2 kernel.

I've bisected the problem in stable/9/sys/ and found that it'd been introduced by r226405 (commit that disables debug options in GENERIC), which is obviously just exposing the bug and not causing it.

Ironically, in head/sys/ the same problem is present but disappears when removing the debug options.

If I attempt to replicate the disk (by creating a new v15 pool and zfs send/receive'ing the data), the destination ZFS pool is bootable unlike the source one. This makes me suspect the problem has something to do with /boot/zfs/zpool.cache.

I'm currently dd'ing the raw partition to another disk to check if the pool can be imported/exported manually, and if "zpool upgrade" has any effect on the problem (I don't want to risk losing the testcase). Please let me know if there's anything else I can try.

>How-To-Repeat:

>Fix:


>Release-Note:
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