Re: Issue with Race Condition on NFS4 with KRB

[Joshua Scoggins <theoretically.x64@gmail.com>]

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.

Joshua Scoggins

On Wed, Jun 22, 2011 at 11:30 AM, Trond Myklebust
<Trond.Myklebust@netapp.com> 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@netapp.com
> www.netapp.com
>
>