Bug 170546

Summary:	kernel_lock() problem through NFS mount
Product:	Red Hat Enterprise Linux 4	Reporter:	Linda Wang <lwang>
Component:	kernel	Assignee:	Steve Dickson <steved>
Status:	CLOSED ERRATA	QA Contact:	Brian Brock <bbrock>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	4.0	CC:	jbaron
Target Milestone:	---
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	RHSA-2006-0132	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2006-03-07 20:23:58 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:
Bug Depends On:
Bug Blocks:	168429

Description Linda Wang 2005-10-12 18:56:36 UTC

From Bugzilla Helper:
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Description of problem:
We have discovered a problem where the kernel lock is still being held by a process
when it returns to user mode.  This results in other processes that are in the kernel
and want the kernel lock spinning inside of lock_kernel() and reacquire_kernel_lock()
even though the real lock holder is no longer in the kernel.

Version-Release number of selected component (if applicable):
kernel-2.6.9

How reproducible:
Always

Steps to Reproduce:
1.install RHEL4
2.mount a nfs filesystem
3.unlock a nfs mounted file
  

Actual Results:  all sorts of weird behavior happens with kernel lock held and going to user space.. espeically on SMP systems, you can notice the slowness of the system since it renders other cpus useless during swapping to user space.

Expected Results:  On smp kernel, there shouldn't be any slowness when a cpu goes into user space.

Additional info:

Comment 1 Linda Wang 2005-10-12 19:00:24 UTC


*** This bug has been marked as a duplicate of 170545 ***

Comment 7 Red Hat Bugzilla 2006-03-07 20:23:59 UTC

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2006-0132.html