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Date:	Sat, 2 Jul 2011 19:07:29 -0700
From:	Joshua Scoggins <theoretically.x64@...il.com>
To:	Trond Myklebust <Trond.Myklebust@...app.com>
Cc:	linux-kernel@...r.kernel.org, linux-nfs@...r.kernel.org
Subject: Re: Issue with Race Condition on NFS4 with KRB

Alright, we finally got the issue solved by rolling back to 2.6.32. It
is faster and that issue hasn't cropped up at all. Hope that helps
you.

Joshua Scoggins
Theoretically.x64@...il.com

On Wed, Jun 22, 2011 at 4:37 PM, Joshua Scoggins
<theoretically.x64@...il.com> wrote:
> I mean it compiled but when I rebooted into the patched kernel. I got
> the same nfs error output
> in dmesg.
>
> Sorry about not being specific.
>
> -Josh
>
> On Wed, Jun 22, 2011 at 4:34 PM, Trond Myklebust
> <Trond.Myklebust@...app.com> wrote:
>> On Wed, 2011-06-22 at 16:23 -0700, Joshua Scoggins wrote:
>>> It's the same error.
>>
>> What mailer are you using to save the attachment? I just grabbed the
>> patch from the reflected email that I received from
>> linux-nfs@...r.kernel.org and again, that applies just fine to both
>> v2.6.39 and the latest kernel from Linus' git tree:
>>
>> [trondmy@...e linux-2.6]$ git checkout -f v2.6.39
>> Warning: you are leaving 1 commit behind, not connected to
>> any of your branches:
>>
>>  9895aa0 SUNRPC: Fix a potential race in between xprt_complete_rqst and xprt_transmit
>>
>> If you want to keep it by creating a new branch, this may be a good time
>> to do so with:
>>
>>  git branch new_branch_name 9895aa06065dd9d457d465f2526a267bec5651a0
>>
>> HEAD is now at 61c4f2c... Linux 2.6.39
>> [trondmy@...e linux-2.6]$ patch -p1 -s -i ~/Desktop/0001-SUNRPC-Fix-a-potential-race-in-between-xprt_complete.patch
>> [trondmy@...e linux-2.6]$
>>
>>
>> That part of the code has not changed for quite some time, so there
>> should be no compatibility problems.
>>
>>> -Josh
>>>
>>> On Wed, Jun 22, 2011 at 4:09 PM, Trond Myklebust
>>> <Trond.Myklebust@...app.com> wrote:
>>> > On Wed, 2011-06-22 at 16:01 -0700, Joshua Scoggins wrote:
>>> >> I just manually applied the patch as I'm using the gentoo sources.
>>> >
>>> > If they're not modifying the source, then it should just apply provided
>>> > that your mailer saved it correctly. If gentoo are applying their own
>>> > patches, then I suggest grabbing a copy of the original 2.6.39 from
>>> > www.kernel.org.
>>> >
>>> >> Josh
>>> >>
>>> >> On Wed, Jun 22, 2011 at 3:53 PM, Trond Myklebust
>>> >> <Trond.Myklebust@...app.com> wrote:
>>> >> > On Wed, 2011-06-22 at 15:40 -0700, Joshua Scoggins wrote:
>>> >> >> The patch isn't applying to the 2.6.39 kernel sources.
>>> >> >
>>> >> > It does for me:
>>> >> >
>>> >> > [trondmy@...e linux-2.6]$ git checkout v2.6.39
>>> >> > HEAD is now at 61c4f2c... Linux 2.6.39
>>> >> > [trondmy@...e linux-2.6]$ git am ~/Desktop/bugfixes/0001-SUNRPC-Fix-a-potential-race-in-between-xprt_complete.patch
>>> >> > Applying: SUNRPC: Fix a potential race in between xprt_complete_rqst and xprt_transmit
>>> >> > [trondmy@...e linux-2.6]$
>>> >> >
>>> >> > Are you perhaps using some distro kernel instead of the regular one from
>>> >> > Linus' repository?
>>> >> >
>>> >> > Cheers
>>> >> >  Trond
>>> >> >
>>> >> >> -Josh
>>> >> >>
>>> >> >> On Wed, Jun 22, 2011 at 2:51 PM, Trond Myklebust
>>> >> >> <Trond.Myklebust@...app.com> wrote:
>>> >> >> > On Wed, 2011-06-22 at 12:18 -0700, Joshua Scoggins wrote:
>>> >> >> >> According to the it guys they are running solaris 10 as the server platform.
>>> >> >> >
>>> >> >> > Ok. That should not be subject to the race I was thinking of...
>>> >> >> >
>>> >> >> >> On Wed, Jun 22, 2011 at 11:57 AM, Trond Myklebust
>>> >> >> >> <Trond.Myklebust@...app.com> wrote:
>>> >> >> >> > 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@...app.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 ]---
>>> >> >> >
>>> >> >> > Looking at the code, there is only one way I can see for that warning to
>>> >> >> > occur, and that is if we put the request back on the 'xprt->recv' list
>>> >> >> > after it has already received a reply from the server.
>>> >> >> >
>>> >> >> > Can you reproduce the problem with the attached patch?
>>> >> >> >
>>> >> >> > Trond
>>> >> >> >
>>> >> >> > --
>>> >> >> > Trond Myklebust
>>> >> >> > Linux NFS client maintainer
>>> >> >> >
>>> >> >> > NetApp
>>> >> >> > Trond.Myklebust@...app.com
>>> >> >> > www.netapp.com
>>> >> >> >
>>> >> >> >
>>> >> >
>>> >> > --
>>> >> > Trond Myklebust
>>> >> > Linux NFS client maintainer
>>> >> >
>>> >> > NetApp
>>> >> > Trond.Myklebust@...app.com
>>> >> > www.netapp.com
>>> >> >
>>> >> >
>>> >> --
>>> >> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
>>> >> the body of a message to majordomo@...r.kernel.org
>>> >> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>> >
>>> > --
>>> > Trond Myklebust
>>> > Linux NFS client maintainer
>>> >
>>> > NetApp
>>> > Trond.Myklebust@...app.com
>>> > www.netapp.com
>>> >
>>> >
>>
>> --
>> Trond Myklebust
>> Linux NFS client maintainer
>>
>> NetApp
>> Trond.Myklebust@...app.com
>> www.netapp.com
>>
>>
>
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