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Bug 746162

Summary: Diskless system hangs when using NFSv4 with system authentication
Product: Red Hat Enterprise Linux 6 Reporter: Ondrej Valousek <ondrejv>
Component: kernelAssignee: Red Hat Kernel Manager <kernel-mgr>
Status: CLOSED NOTABUG QA Contact: Red Hat Kernel QE team <kernel-qe>
Severity: medium Docs Contact:
Priority: unspecified    
Version: 6.1CC: bfields, dhowells, jlayton, rwheeler, sprabhu, steved
Target Milestone: rc   
Target Release: ---   
Hardware: x86_64   
OS: All   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2011-10-18 13:00:39 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Attachments:
Description Flags
/var/log/messages from a diskless system running RHEL-6 none

Description Ondrej Valousek 2011-10-14 07:21:27 UTC
Created attachment 528160 [details]
/var/log/messages from a diskless system running RHEL-6

System hangs when (processes stuck in the D state) a diskless system booting from a NFS server uses NFSv4.
A SysRQ traces and the kernel log is attached.

The problem is easily reproducible.

Comment 2 Ondrej Valousek 2011-10-14 07:48:02 UTC
Note that the "adclient" process that you see stuck in the D state is getting
user/group attributes (UIDs/GIDs) from Active Directory.
I guess there must be some dead loop here as well where rpc.idmapd is asking
for user's name and hence it uses (indirectly, via the NSS library) adclient to
complete the job.

I am looking for some ideas on how to avoid this situation.

Ondrej

Comment 3 J. Bruce Fields 2011-10-14 21:37:58 UTC
Does adclient need to access nfs?  If so, then no, this isn't going to work....

Comment 4 Ondrej Valousek 2011-10-18 07:41:28 UTC
Did some more investigation and it turned out that adclient uses /var/centrifydc directory which _was_ mounted via NFSv4.
The problem seems to vanish (I can not replicate) if I mount the directory via NFSv3 - which makes a sense actually.

Sorry for wasting your time here - please close this call.
Thanks,

Ondrej

Comment 5 J. Bruce Fields 2011-10-18 13:00:39 UTC
(In reply to comment #4)
> Did some more investigation and it turned out that adclient uses
> /var/centrifydc directory which _was_ mounted via NFSv4.
> The problem seems to vanish (I can not replicate) if I mount the directory via
> NFSv3 - which makes a sense actually.

Yes, that's as expected; thanks for the confirmation.