From: Garrick Staples <garrick@usc.edu>
Subject: Re: mountd segfault on itanium2
Date: Fri, 30 Apr 2004 16:43:27 -0700
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On Fri, Apr 30, 2004 at 02:24:14PM -0700, Garrick Staples alleged:
> Hi all,
>    I'm having a terrible time with mountd segfaulting on two Itanium boxe=
s.  I
> can't find a specific trigger, but I can generally trigger it within a few
> minutes by just calling mount/umount a few hundred times.
>=20
> I'm using glibc 2.3.2 and nfs-utils 1.0.6 from RHE.
>=20
> In the tests below, I have a single directory exported to 10.125.0.0/16. =
 Since
> I know name resolution was a recent problem, I've made sure all clients a=
re in
> /etc/hosts.  I'm using NIS, but files is before dns and nis in nsswitch.c=
onf.
> I've also tested with and without nscd running.

> select(1024, [3 4 5 6 7], NULL, NULL, NULL) =3D 2 (in [5 6])
> read(5, "", 0)                          =3D 0
> --- SIGSEGV (Segmentation fault) @ 20000008002c19d0 (63742f3132353111) ---

> write(5, "10.125.0.0/16 0 \\x00080011020000"..., 62) =3D 62
> --- SIGSEGV (Segmentation fault) @ 20000000002899d0 (7064752f35343639) ---


I just spotted a pattern.  After collecting several strace samples, it alwa=
ys
segfaults after read() or write() to fd 5.  And fd 5 is always:

   open("/proc/net/rpc/nfsd.fh/channel", O_RDWR) =3D 5

I have no idea what the file is for, but grep'ing my straces shows that mou=
ntd
doesn't normally use it.  It can handle hundreds of mount/umount requests
without ever touching fd 5.  Then at some point it reads once:

   read(5, "10.125.0.0/16 0 \\x00080011020000"..., 128) =3D 35

If it doesn't segfault on the read(), it might segfault on a write() very s=
oon
after:

   write(5, "10.125.0.0/16 0 \\x00080011020000"..., 62) =3D 62


Thanks in advance to anyone that knows what's going on.

--=20
Garrick Staples, Linux/HPCC Administrator
University of Southern California

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