Re: [Bugme-new] [Bug 8724] New: Unaligned acess in udp_recvmsg() on EV56

On Sun,  8 Jul 2007 14:30:17 -0700 (PDT) bugme-daemon@bugzilla.kernel.org wrote:

http://bugzilla.kernel.org/show_bug.cgi?id=8724

           Summary: Unaligned acess in udp_recvmsg() on EV56
           Product: Platform Specific/Hardware
           Version: 2.5
     KernelVersion: 2.6.22-rc7-git7
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Alpha
        AssignedTo: rth@twiddle.net
        ReportedBy: jailbird@alcatraz.fdf.net


Most recent kernel where this bug did not occur: Occurs in all 2.6.2[12] at
least
Distribution: Debian testing/lenny
Hardware Environment: Digital PWS 433au (EV56)
Software Environment:
Linux utopia 2.6.22-rc7-git7 #1 Thu Jul 8 10:34:17 CDT 2027 alpha GNU/Linux

Gnu C                  4.2.1
Gnu make               3.81
binutils               (GNU Binutils for Debian) 2.17.50.20070426
util-linux             2.12r
mount                  2.12r
module-init-tools      3.3-pre11
e2fsprogs              1.40-WIP
xfsprogs               2.8.18
Linux C Library        > libc.2.5
Dynamic linker (ldd)   2.5
Procps                 3.2.7
Net-tools              1.60
Kbd                    85:
Sh-utils               5.97
udev                   105
Modules Loaded         ipt_TOS xt_multiport xt_tcpudp xt_state ip6table_mangle
ip6table_filter ip6_tables ipv6 iptable_nat nf_nat nf_conntrack_ipv4
nf_conntrack iptable_mangle iptable_filter ip_tables x_tables dm_mod serio_raw
mxser_new ide_generic via_rhine mii generic ide_core tulip bitrev crc32 sg
sr_mod cdrom raid1 md_mod loop

Problem Description:
kernel unaligned acc    : 2248 (pc=fffffc0000583de4,va=fffffc00071c382a)

fffffc0000583bc0 T udp_recvmsg
fffffc0000583ed0 T udp_destroy_sock

kernel unaligned acc    : 1231 (pc=fffffc0000585190,va=fffffc000795e02e)

fffffc0000585120 T __udp4_lib_rcv
fffffc0000585bf0 T udp_rcv

This problem does NOT seem to affect my Tsunami/Shark (EV68AL) box running the
same kernel version on the same LAN.  Not sure if it's CPU generation related
(EV5 vs EV6), or if it's the NIC (via_rhine on the EV5 vs e100 on the EV6).

Steps to reproduce:
According to tshark, the only UDP packets are DHCP packets:

1815064200.131003   10.5.128.1 -> 255.255.255.255 DHCP DHCP Offer    -
Transaction ID 0x27c6

That output isn't terribly illuminating.  We'd need to work out
which code corresponds with pc=fffffc0000583de4 and
pc=fffffc0000585190.

I don't think there's necessarily a bug here: that's just the kernel
telling us that there are unaligned accesses which got successfully
fixed up, so we're being perhaps a bit inefficient.  Yes?