Re: Issue with Race Condition on NFS4 with KRB

From: Trond Myklebust
Date: Wed Jun 22 2011 - 14:57:41 EST


On Wed, 2011-06-22 at 11:37 -0700, Joshua Scoggins wrote:
> Here are our mount options from auto.master
>
> /user -fstype=nfs4,sec=krb5p,noresvport,noatime
> /group -fstype=nfs4,sec=krb5p,noresvport,noatime
>
> As for the server, we don't control it. It's actually run by the
> campus wide it department we are just lab support for CS. I can
> potentially get the server information but I need to know what you want
> specifically as they're pretty paranoid about giving out information about
> their servers.

I would just want to know _what_ server platform you are running
against. I know of at least one server bug that might explain what you
are seeing, and I'd like to eliminate that as a possibility.

Trond

> Joshua Scoggins
>
> On Wed, Jun 22, 2011 at 11:30 AM, Trond Myklebust
> <Trond.Myklebust@xxxxxxxxxx> wrote:
> > On Wed, 2011-06-22 at 11:21 -0700, Joshua Scoggins wrote:
> >> Hello,
> >>
> >> We are trying to update our linux images in our CS lab and have it a
> >> bit of an issue. We are
> >> using nfs to load user home folder. While testing the new image we
> >> found that the nfs4 module will
> >> crash when using firefox 3.6.17 for an extended period of time. Some
> >> research via google yielded that
> >> it's a potential race condition specific to nfs with krb auth with
> >> newer kernels. Our old image doesn't have
> >> this issue and it seems that its due to it running a far older kernel version.
> >>
> >> We have two images and both are having this problem. One is running
> >> 2.6.39 and the other is 2.6.38.
> >> Here is what dmesg spit out from the machine running 2.6.39 on one occasion:
> >>
> >> [ 678.632061] ------------[ cut here ]------------
> >> [ 678.632068] WARNING: at net/sunrpc/clnt.c:1567 call_decode+0xb2/0x69c()
> >> [ 678.632070] Hardware name: OptiPlex 755
> >> [ 678.632072] Modules linked in: nvidia(P) scsi_wait_scan
> >> [ 678.632078] Pid: 3882, comm: kworker/0:2 Tainted: P
> >> 2.6.39-gentoo-r1 #1
> >> [ 678.632080] Call Trace:
> >> [ 678.632086] [<ffffffff81035b20>] warn_slowpath_common+0x80/0x98
> >> [ 678.632091] [<ffffffff8117231e>] ? nfs4_xdr_dec_readdir+0xba/0xba
> >> [ 678.632094] [<ffffffff81035b4d>] warn_slowpath_null+0x15/0x17
> >> [ 678.632097] [<ffffffff81426f48>] call_decode+0xb2/0x69c
> >> [ 678.632101] [<ffffffff8142d2b5>] __rpc_execute+0x78/0x24b
> >> [ 678.632104] [<ffffffff8142d4c9>] ? rpc_execute+0x41/0x41
> >> [ 678.632107] [<ffffffff8142d4d9>] rpc_async_schedule+0x10/0x12
> >> [ 678.632111] [<ffffffff8104a49d>] process_one_work+0x1d9/0x2e7
> >> [ 678.632114] [<ffffffff8104c402>] worker_thread+0x133/0x24f
> >> [ 678.632118] [<ffffffff8104c2cf>] ? manage_workers+0x18d/0x18d
> >> [ 678.632121] [<ffffffff8104f6a0>] kthread+0x7d/0x85
> >> [ 678.632125] [<ffffffff8145e314>] kernel_thread_helper+0x4/0x10
> >> [ 678.632128] [<ffffffff8104f623>] ? kthread_worker_fn+0x13a/0x13a
> >> [ 678.632131] [<ffffffff8145e310>] ? gs_change+0xb/0xb
> >> [ 678.632133] ---[ end trace 6bfae002a63e020e ]---
> >>
> >> Is there some sort of work around?
> >
> > Cced the linux-nfs mailing list.
> >
> > The above warning is not specific to krb5, but indicates a likely race
> > between replies after a resend of the RPC call.
> >
> > Can you please tell us what your mount options are, and also tell us a
> > bit more about what kind of server you are running against?
> >
> > Trond
> > --
> > Trond Myklebust
> > Linux NFS client maintainer
> >
> > NetApp
> > Trond.Myklebust@xxxxxxxxxx
> > www.netapp.com
> >
> >

--
Trond Myklebust
Linux NFS client maintainer

NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com

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