Bug 683073

Summary:	page_referenced() sometime ignores young bits with THP
Product:	Red Hat Enterprise Linux 6	Reporter:	Andrea Arcangeli <aarcange>
Component:	kernel	Assignee:	Andrea Arcangeli <aarcange>
Status:	CLOSED ERRATA	QA Contact:	Caspar Zhang <czhang>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	6.1	CC:	czhang, qcai, tburke
Target Milestone:	rc	Keywords:	Triaged
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	kernel-2.6.32-128.el6	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2011-05-19 11:59:58 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:

Description Andrea Arcangeli 2011-03-08 13:15:43 UTC

Description of problem: sometime the young bits could be ignored erroneously on hugepages with page_referenced()


Version-Release number of selected component (if applicable): 6.0 and 6.1


How reproducible: Not easily reproducible. It may generate some unnecessary swapping.


Steps to Reproduce:
1. allocate memory, bzero it
2. fork()
3. bzero the memory in the child to trigger cows and mlock the memory in the child
  
Actual results:

The pages in the parent shouldn't be easily swapped out.

Expected results:

The pages in the parent are more easily swapped out than expected.

Comment 2 Andrea Arcangeli 2011-03-08 13:43:32 UTC

I submitted a fix that applies to both RHEL6 and RHEL6.1 kernels on rhkernel-list with Message-ID: <20110308134243.GT25641>

Comment 3 RHEL Program Management 2011-03-14 13:20:43 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.

Comment 4 Aristeu Rozanski 2011-03-30 14:32:15 UTC

Patch(es) available on kernel-2.6.32-128.el6

Comment 10 errata-xmlrpc 2011-05-19 11:59:58 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 therefore 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-2011-0542.html