kern/73094: [unionfs] system runs out of vnodes

[David Schultz]

The following reply was made to PR kern/73094; it has been noted by GNATS.

From: David Schultz <das at FreeBSD.ORG>
To: Irina Liakh <spell at itl.ua>
Cc: FreeBSD-gnats-submit at FreeBSD.ORG
Subject: Re: kern/73094: [unionfs] system runs out of vnodes
Date: Mon, 25 Oct 2004 16:47:34 -0400

 On Mon, Oct 25, 2004, Irina Liakh wrote:
 > In normal situation, when vnode count is going
 > to be over, getnewvnode() routine tries
 > to reuse (by vtryrecycle()) existing but freed vnodes,
 > and numvnodes (sysctl vfs.numvnodes) stops growing.
 > When using unionfs (accessing files in it),
 > vtryrecycle() always fails. The reason is non-zero
 > resident_page_count field in vm_object_t-object
 > corresponding to vnode-to-be-reused.
 > Hence, getnewvnode() allocates new vnodes
 > until numvnodes minus freevnodes becomes greater than
 > desiredvnodes, after what every getnewvnode() goes to
 > sleep with status-for-ps "vlruwk".
 
 What makes you think this has something to do with the resident
 page count, as opposed to v_usecount?