After updating to the current kernel (2.6.27.29-0.1) all NFS4 mounts fail with EINVAL. This is found at the system call level with strace as well as calling mount(2) directly from a C program. No traffic is sent to the server. portmapper, gssd, and idmapd are all running. NFS4 mounts were working fine prior to this update.

Verified for 64-bit xen kernel, 32-bit pae kernel, and 32-bit default kernel. Haven't tested the 64-bit default kernel. Our only workaround is to back out this update.

# uname -a
Linux manbearpig 2.6.27.29-0.1-default #1 SMP 2009-08-15 17:53:59 +0200 i686 i686 i386 GNU/Linux
# rpm -q nfs-client
nfs-client-1.1.3-18.2.1
# lsmod
Module Size Used by
xt_pkttype 1560 4
snd_pcm_oss 43132 0
snd_mixer_oss 14288 1 snd_pcm_oss
snd_seq 51920 0
snd_seq_device 7168 1 snd_seq
rpcsec_gss_krb5 9200 0
auth_rpcgss 33564 1 rpcsec_gss_krb5
nfs 253112 0
lockd 61528 1 nfs
nfs_acl 2852 1 nfs
sunrpc 182024 8 rpcsec_gss_krb5,auth_rpcgss,nfs,lockd,nfs_acl
af_packet 16344 2
xt_tcpudp 2728 24
ipt_LOG 5708 0
ipt_MASQUERADE 3168 0
nf_nat_ftp 3552 0
iptable_nat 5908 0
nf_nat 19544 3 ipt_MASQUERADE,nf_nat_ftp,iptable_nat
nf_conntrack_irc 6324 0
nf_conntrack_ftp 13120 1 nf_nat_ftp
microcode 10896 0
ip6t_REJECT 4984 3
nf_conntrack_ipv6 20108 4
ip6table_raw 1792 1
xt_NOTRACK 1544 4
ipt_REJECT 2760 3
xt_state 1904 8
iptable_raw 2056 1
iptable_filter 2548 1
ip6table_mangle 2288 0
nf_conntrack_ipv4 10480 7 iptable_nat,nf_nat
nf_conntrack 67328 10 ipt_MASQUERADE,nf_nat_ftp,iptable_nat,nf_nat,nf_conntrack_irc,nf_conntrack_ftp,nf_conntrack_ipv6,xt_NOTRACK,xt_state,nf_conntrack_ipv4
ip_tables 11276 3 iptable_nat,iptable_raw,iptable_filter
ip6table_filter 2408 1
ip6_tables 12496 3 ip6table_raw,ip6table_mangle,ip6table_filter
x_tables 14416 11 xt_pkttype,xt_tcpudp,ipt_LOG,ipt_MASQUERADE,iptable_nat,ip6t_REJECT,xt_NOTRACK,ipt_REJECT,xt_state,ip_tables,ip6_tables
ipv6 242248 37 ip6t_REJECT,nf_conntrack_ipv6,ip6table_mangle
fuse 50644 1
loop 14112 0
dm_mod 62596 0
ppdev 6876 0
tulip 46300 0
snd_intel8x0 28256 0
snd_ac97_codec 99756 1 snd_intel8x0
ac97_bus 1584 1 snd_ac97_codec
snd_pcm 76768 3 snd_pcm_oss,snd_intel8x0,snd_ac97_codec
snd_timer 20204 2 snd_seq,snd_pcm
button 6568 0
iTCO_wdt 9940 0
iTCO_vendor_support 3368 1 iTCO_wdt
snd 56800 8 snd_pcm_oss,snd_mixer_oss,snd_seq,snd_seq_device,snd_intel8x0,snd_ac97_codec,snd_pcm,snd_timer
intel_agp 24436 0
tg3 113812 0
soundcore 6660 1 snd
i2c_i801 10500 0
parport_pc 34616 0
agpgart 32148 1 intel_agp
rtc_cmos 10744 0
dcdbas 8888 0
snd_page_alloc 8048 2 snd_intel8x0,snd_pcm
libphy 18976 1 tg3
pcspkr 2344 0
i2c_core 29892 1 i2c_i801
parport 33128 2 ppdev,parport_pc
rtc_core 17384 1 rtc_cmos
sr_mod 13360 0
serio_raw 5096 0
rtc_lib 2816 1 rtc_core
cdrom 32288 1 sr_mod
sg 29392 0
usbhid 45540 0
hid 35568 1 usbhid
ff_memless 7132 1 usbhid
sd_mod 31632 5
crc_t10dif 1704 1 sd_mod
ehci_hcd 47488 0
uhci_hcd 22976 0
usbcore 165556 4 usbhid,ehci_hcd,uhci_hcd
sata_nv 21544 0
edd 8620 0
ext3 124012 3
mbcache 7592 1 ext3
jbd 52796 1 ext3
fan 4720 0
ide_pci_generic 3428 0
piix 5868 0
ide_core 97108 2 ide_pci_generic,piix
ata_generic 4484 0
ata_piix 16600 4
libata 160944 3 sata_nv,ata_generic,ata_piix
scsi_mod 149760 4 sr_mod,sg,sd_mod,libata
dock 11844 1 libata
thermal 19976 0
processor 43284 1 thermal
thermal_sys 11376 3 fan,thermal,processor
hwmon 2916 1 thermal_sys