kern/187414: ZFS Write Deadlock

[Gordon Yeu]

>Number:         187414
>Category:       kern
>Synopsis:       ZFS Write Deadlock
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Mar 10 11:40:00 UTC 2014
>Closed-Date:
>Last-Modified:
>Originator:     Gordon Yeu
>Release:        8.4-STABLE
>Organization:
>Environment:
FreeBSD kmd.twbbs.org 8.4-STABLE FreeBSD 8.4-STABLE #6 r262357: Sun Feb 23 18:38:39 CST 2014     root at kmd.twbbs.org:/usr/obj/usr/src/sys/MERCURY  amd64
>Description:
Just did a periodical update to 8.4-STABLE r262357 on a self-build home server. The only change I did after update is upgrade zpool version to latest (version 28). My zpool is in mirror configuration, built from dual Seagate 3TB hard drives (ST3000DM001). 


Moving large files in ~4GB size hangs the target directory, and Bonnie++ leads to deadlock as well. So I believe it was caused by large write operations. 

Here are logs for both cases. 
mv: procstat -kk -a 
http://pastebin.com/WManZzbv 

bonnie++: procstat -kk -a 
http://pastebin.com/fe2bmbbY 

bonnie++: kgdb (thread apply all bt) 
http://pastebin.com/kdm5xQwM 
>How-To-Repeat:
run bonnie++ and set -d scratch-dir on ZFS.
>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: