Bug 91773

Summary: (VM)Stopping and restarting kupdated makes it use 100% CPU time
Product: [Retired] Red Hat Linux Reporter: Christian Bauer <cb>
Component: kernelAssignee: Arjan van de Ven <arjanv>
Status: CLOSED WONTFIX QA Contact: Brian Brock <bbrock>
Severity: medium Docs Contact:
Priority: medium    
Version: 9CC: kobras, riel, veeshooter
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Target Release: ---   
Hardware: i586   
OS: Linux   
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Fixed In Version: Doc Type: Bug Fix
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Clone Of: Environment:
Last Closed: 2004-09-30 15:41:00 UTC Type: ---
Regression: --- Mount Type: ---
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Description Christian Bauer 2003-05-27 22:53:34 UTC
From Bugzilla Helper:
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Description of problem:
After stopping and continuing the kupdated process by sending it a SIGSTOP
followed by a SIGCONT, the process uses up 100% CPU time and continues to do so
until the machine is rebooted (or kupdated is stopped again).

Version-Release number of selected component (if applicable):
kernel-2.4.20-13.9

How reproducible:
Always

Steps to Reproduce:
1. kill -STOP `pidof kupdated`
2. kill -CONT `pidof kupdated`
3. top


Actual Results:  kupdated shows close to 100% CPU usage in the 'top' display.

Expected Results:  kupdated remains a background process, as after a fresh boot.

Additional info:

This bug causes problems with noflushd which uses SIGSTOP to suspend kupdated
when the hard disk is spun down.

Downgrading to kernel-2.4.20-13.8 from Red Hat 8.0 solves the issue.
A stock 2.4.20 kernel also doesn't show this behavior.

Comment 1 Mike Hockings 2004-01-31 18:27:40 UTC
This problem is also present in the current (2.4.22-1.2149.nptl) 
kernel.  Simply issuing the command

killall -STOP kupdated

will cause kupdated to consume 88% or more (typically over 90%) of 
the cpu.  All attempts to bring the cpu usage down short of a reboot 
have not been successful.


Comment 2 Bugzilla owner 2004-09-30 15:41:00 UTC
Thanks for the bug report. However, Red Hat no longer maintains this version of
the product. Please upgrade to the latest version and open a new bug if the problem
persists.

The Fedora Legacy project (http://fedoralegacy.org/) maintains some older releases, 
and if you believe this bug is interesting to them, please report the problem in
the bug tracker at: http://bugzilla.fedora.us/