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Description of problem:
As the Bug 756307 modified, it will not init the xen platform pci when the kernel option xen_emul_unplug=nerver added.
While, the Call Trace keep printing on the RHEL6.3 guest console when :
a) with option "xen_emul_unplug=nerver" added in kernel cmd line.
b) use NIC with the type of netfront
INFO: task rhsmd:26621 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
rhsmd D 0000000000000000 0 26621 26619 0x00000080
ffff88003df15cf8 0000000000000082 000000023df15ca8 0000000000000000
ffff880000019718 00000037ffffffc8 ffff88000002ab00 0000000000000000
ffff88003df9d058 ffff88003df15fd8 000000000000fac8 ffff88003df9d058
Call Trace:
[<ffffffff810909ae>] ? prepare_to_wait+0x4e/0x80
[<ffffffff81306cb5>] read_reply+0xb5/0x140
[<ffffffff810906c0>] ? autoremove_wake_function+0x0/0x40
[<ffffffff81306e64>] xs_talkv+0xe4/0x1e0
[<ffffffff813070cb>] xs_single+0x4b/0x60
[<ffffffff81307838>] xenbus_read+0x48/0x70
[<ffffffff8130a187>] uuid_show+0x57/0xc0
[<ffffffff81309f9c>] hyp_sysfs_show+0x1c/0x20
[<ffffffff811ee1b1>] sysfs_read_file+0x111/0x1f0
[<ffffffff81179745>] vfs_read+0xb5/0x1a0
[<ffffffff810d4fa2>] ? audit_syscall_entry+0x272/0x2a0
[<ffffffff81179881>] sys_read+0x51/0x90
[<ffffffff8100b0f2>] system_call_fastpath+0x16/0x1b
Version-Release number of selected component (if applicable):
Host:
kernel-xen-2.6.18-308.el5
xen-3.0.3-135.el5
Guest:
2.6.32-250.el6
How reproducible:
100%
Steps to Reproduce:
1. Add option "xen_emul_unplug=nerver" to guest kernel cmd line .
2. Create the guest with NIC type of netfront .
3. Wait for a long time (such as couple of hours), then Call Trace keep printing in on the console at the interval of 120 seconds.
Actual results:
Call Trace printed on the console.
Expected results:
No Call Trace printed on the console.
Additional info:
Could be reproduced faster with command 'cat /sys/hypervisor/uuid' in guest and we have the same trace:
INFO: task cat:9120 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
cat D 0000000000000000 0 9120 1157 0x00000080
ffff88010ba9fcf8 0000000000000082 0000000000000000 0000000000000000
ffff880000025dd8 00000037ffffffc8 ffff88000002eb00 0000000000000000
ffff8801084c45f8 ffff88010ba9ffd8 000000000000fac8 ffff8801084c45f8
Call Trace:
[<ffffffff81306cb5>] read_reply+0xb5/0x140
[<ffffffff810906c0>] ? autoremove_wake_function+0x0/0x40
[<ffffffff81306e64>] xs_talkv+0xe4/0x1e0
[<ffffffff813070cb>] xs_single+0x4b/0x60
[<ffffffff81307838>] xenbus_read+0x48/0x70
[<ffffffff8130a187>] uuid_show+0x57/0xc0
[<ffffffff81309f9c>] hyp_sysfs_show+0x1c/0x20
[<ffffffff811ee1b1>] sysfs_read_file+0x111/0x1f0
[<ffffffff81179745>] vfs_read+0xb5/0x1a0
[<ffffffff810d4fa2>] ? audit_syscall_entry+0x272/0x2a0
[<ffffffff81179881>] sys_read+0x51/0x90
[<ffffffff8100b0f2>] system_call_fastpath+0x16/0x1b
BTW
it is not necessary to have netfront nic in config.
Upstream a947f0f8f70 sort of "fixes" it. i.e. it returns -EBUSY instead of hanging on read.
Question is if this is suitable for RHEL since initially bug was triggered by rhsmd from subscription-manager.
Bryan,
Is it mandatory for files in /sys/hypervisor be readable and return meaningful values?
rhsmd reads /sys/hypervisor/uuid to figure out the guest's virt uuid, so we can do guest/host association, and grant free entitlements as appropriate.
Unless there's another way a xen guest can figure out its virt uuid, having access to /sys/hypervisor is pretty important for us.
Comment 8Richard W.M. Jones
2012-03-19 14:00:19 UTC
virt-what reads /sys/hypervisor/type (not /sys/hypervisor/uuid).
We've not seen a problem before, and IMHO if reading this file
causes a kernel timeout, then it's a bug in the kernel, but I'm
not sure I have the full picture of what is going on.
Comment 9RHEL Program Management
2012-03-20 16:10:31 UTC
This request was evaluated by Red Hat Product Management for inclusion
in a Red Hat Enterprise Linux maintenance release. Product Management has
requested further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products. This request is not yet committed for inclusion in an Update release.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
http://rhn.redhat.com/errata/RHSA-2012-0862.html