Subject: kern/18036: nfs client deadlock
To: None <>
From: None <>
List: netbsd-bugs
Date: 08/22/2002 19:25:59
>Number:         18036
>Category:       kern
>Synopsis:       nfs client deadlock
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Aug 22 03:42:00 PDT 2002
>Originator:     YAMAMOTO Takashi <>
>Release:        NetBSD 1.6F
System: NetBSD capybara 1.6F NetBSD 1.6F (build.stg) #: Thu Aug 22 12:36:01 JST 2002 takashi@capybara:/usr/home/takashi/work/kernel/build.stg i386
Architecture: i386
Machine: i386
	reading files over nfs:

	nfs_read -> uvm_fault -> genfs_getpages (the page is locked)
	-> nfs_strategy -> nfs_readrpc -> nfs_loadattrcache

	now, suppose that read rpc call was succeed
	but file size in postattr is truncated.

	nfs_loadattrcache -> uvm_vnp_setsize -> genfs_putpages

	then genfs_putpages notices page is marked as busy
	and wait on it.  but it'll never be freed because
	it's owned by ourselves. => deadlock

	truncate a file on server or another client
	during netbsd client is reading it.