Bug 10177 - _stp_kill_time on RT-kernel hits BUG
Summary: _stp_kill_time on RT-kernel hits BUG
Status: RESOLVED FIXED
Alias: None
Product: systemtap
Classification: Unclassified
Component: runtime (show other bugs)
Version: unspecified
: P2 normal
Target Milestone: ---
Assignee: Unassigned
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2009-05-20 19:30 UTC by Josh Stone
Modified: 2009-05-21 15:25 UTC (History)
0 users

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Description Josh Stone 2009-05-20 19:30:25 UTC 
See http://sourceware.org/ml/systemtap/2009-q2/msg00635.html

In particular:

BUG: scheduling while atomic: stapio/0x00000001/26142, CPU#3
[...]
 [<ffffffff812a2dea>] cpufreq_unregister_notifier+0x35/0x5c
 [<ffffffffa02e0a1f>] _stp_kill_time+0xb6/0xbd
[stap_246f93f30a500769142af9987624737a_5072]
 [<ffffffffa02e1749>] probe_1391+0x3c/0xa8
[stap_246f93f30a500769142af9987624737a_5072]
 [<ffffffffa02e2621>] enter_end_probe+0x14a/0x1e3
[stap_246f93f30a500769142af9987624737a_5072]

It seems that cpufreq_unregister_notifier is sleepy, and so shouldn't be called
from probe context.
Comment 1 Josh Stone 2009-05-20 22:00:12 UTC 
This should be fixed in git now, but I don't have an RT kernel to test with. 
Please test and confirm with this fix:

commit 29e2616aeeb82605a6efe1dbc574b499781eafbe
Author: Josh Stone <jistone@redhat.com>
Date:   Wed May 20 14:46:25 2009 -0700

    PR10177: init/kill time in sleepy context only
Comment 2 Kiran 2009-05-21 09:00:06 UTC 
Hi Josh,
I tested your fix with RT kernel. The bug is resolved now. Thanks a lot
Comment 3 Josh Stone 2009-05-21 15:25:29 UTC 
Fix confirmed...