kern/144330: mbuf leakage in nfsd with zfs

[Gerrit Kühn]

>Number:         144330
>Category:       kern
>Synopsis:       mbuf leakage in nfsd with zfs
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Feb 26 21:40:02 UTC 2010
>Closed-Date:
>Last-Modified:
>Originator:     Gerrit Kühn
>Release:        8-stable as of 24th of Feb
>Organization:
AEI
>Environment:
FreeBSD mclane.rt.aei.uni-hannover.de 8.0-STABLE FreeBSD 8.0-STABLE #2: Fri Feb 26 14:15:47 CET 2010     root at mclane.rt.aei.uni-hannover.de:/usr/obj/usr/src/sys/GENERIC  amd64

>Description:
When serving nfs dirs from a zfs storage, mbuffers keep being drained, but are never freed. See http://www.pmp.uni-hannover.de/test/Mitarbeiter/g_kuehn/data/mbuf.pdf as an example. y-axis is output of total mbuf clusters by netstat -m, x-axis is time in minutes. The flat region in the upper right corner corresponds to approx. 10min with nfsd turned off.
Several others report similar problems (see thread on -stable with topic "mbuf leakage with nfs/zfs? (was: em0 freezes on ZFS server)").
>How-To-Repeat:
Server nfs-dirs from zfs storage with 8-stable and monitor mbuf usage.
>Fix:
Unknown, but urgently needed. :-)


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