kern/53664: nfs client broken on netbsd-8

[htodd%i8u.org@localhost]

>Number:         53664
>Category:       kern
>Synopsis:       nfs client broken on netbsd-8
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Oct 09 03:20:00 +0000 2018
>Originator:     htodd%i8u.org@localhost
>Release:        NetBSD 8.0_STABLE
>Organization:
	
>Environment:
	
	
System: NetBSD emily.i8u.org 8.0_STABLE NetBSD 8.0_STABLE (EMILY) #139: Mon Oct 8 20:00:22 PDT 2018 htodd%chris.i8u.org@localhost:/usr/obj/i386/sys/arch/i386/compile/EMILY i386
Architecture: i386
Machine: i386
>Description:
This also happens on netbsd-8-amd64.

My mount script is:
#!/bin/sh

if test "$(id -u)" -ne "0"; then
   echo "Run this script as root" 1>&2
   exit 1
fi

/sbin/mount_nfs -o ro mara:/mnt2/home/netbsd-cvs/netbsd-8/src /usr/src
/sbin/mount_nfs -o ro mara:/mnt2/home/netbsd-cvs/netbsd-8/xsrc /usr/xsrc

# /sbin/mount_nfs -o ro mara:/home/netbsd/pkgsrc-2014Q4/pkgsrc /usr/pkgsrc
# /sbin/mount_nfs mara:/home/netbsd/pkgsrc/pkgsrc-2012Q4/packages/All/i386-fw /usr/pkgsrc/packages/All
/sbin/mount_nfs -o ro mara:/mnt2/home/netbsd-cvs/pkgsrc-2018Q3/pkgsrc /usr/pkgsrc

The mount of pkgsrc hangs. rpcmount and showmount looked normal, so I decided to bisect the kernel using git.

The result is:
24fcafa1a5051620452bb42e7b433d462764340f is the first bad commit
commit 24fcafa1a5051620452bb42e7b433d462764340f
Author: martin <martin%netbsd.org@localhost>
Date:   Wed Oct 3 17:53:56 2018 +0000

    Pull up following revision(s) (requested by maxv in ticket #1045):

            sys/netinet/ip_reass.c: revision 1.19

    Hold ip_off and ip_len in the fragment entry, instead of always reading
    the associated mbuf (and converting to host order). This reduces the
    cache/TLB misses when processing long lists.

>How-To-Repeat:
build a kernel with the changes to ip_reass.c using:
/usr/src/build.sh -O /usr/obj/i386 -T /usr/obj/tools.i386 -U -m i386 -j$JOBS kernel=EMILY

>Fix:
Phooey, I forgot to revert just that commit. I'll add that to the pr later.

>Unformatted: