[OpenAFS] RE: [OpenAFS-announce] OpenAFS client crashes on RHEL 5.10 and RHEL 6.5

Devine, Steven sd@msu.edu
Fri, 7 Mar 2014 21:18:37 +0000

Is there any data on this behaviour on CentOS ? =0A=
Steve Devine=0A=
Michigan State University=0A=
From: openafs-announce-admin@openafs.org [openafs-announce-admin@openafs.or=
g] on behalf of Andrew Deason [adeason@sinenomine.net]=0A=
Sent: Friday, March 07, 2014 11:03 AM=0A=
To: openafs-announce@openafs.org=0A=
Cc: openafs-info@openafs.org=0A=
Subject: [OpenAFS-announce] OpenAFS client crashes on RHEL 5.10 and RHEL 6.=
It has been discovered that the OpenAFS client interacts poorly with a=0A=
change to the Linux kernel introduced in Red Hat Enterprise Linux=0A=
versions 5.10 and 6.5, which can cause a kernel panic with certain AFS=0A=
access patterns. Sites may want to exercise caution when considering=0A=
upgrading RHEL systems that are running OpenAFS clients.=0A=
While the mechanism that is causing this problem is understood and a=0A=
solution is being developed, fixing this issue is not straightforward=0A=
and may take some time. In the meantime, without a fix in place, the=0A=
following workarounds may help avoid encountering the issue:=0A=
 - Avoid using multiple different mountpoints to access the same data,=0A=
   since this can confuse the Linux VFS in some situations. This may be=0A=
   difficult to guarantee (since /afs/cellname and /afs/.cellname=0A=
   usually exist), but it may be possible to reduce such mountpoint=0A=
   usage in some scenarios.=0A=
 - Avoid running the RHEL 5.10 kernel or the RHEL 6.5 kernel on machines=0A=
   with OpenAFS clients. However, these kernel updates contain stability=0A=
   and security fixes, so it may not be desirable to avoid upgrading=0A=
   such machines running OpenAFS clients.=0A=
Note that the RHEL 7 Beta is not affected by this issue, but it is not=0A=
known if the final release of RHEL 7 will. No other distributions of=0A=
Linux are known to be affected by this (except any that are derived from=0A=
RHEL), and the problematic change to the Linux kernel is not in vanilla=0A=
upstream Linux kernel releases.=0A=
If your site has a support contract with Red Hat, you may wish to=0A=
inquire about this issue through your support channel. For reference,=0A=
the issue was introduced in RHEL5 in kernel 2.6.18-367.el5 with this=0A=
 - [fs] vfs: stop d_splice_alias creating directory aliases (J. Bruce Field=
s) [785916]=0A=
and in RHEL6 in kernel 2.6.32-408.el6 with this change:=0A=
 - [fs] vfs: stop d_splice_alias creating directory aliases (J. Bruce Field=
s) [820446]=0A=
For more details and future updates on this issue, see this RT ticket:=0A=
Andrew Deason=0A=
OpenAFS-announce mailing list=0A=