Bug 644037 – kernel BUG at mm/huge_memory.c:1267! - mapcount 5 page_mapcount 4 [rhel-6.0.z]

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Bug 644037 - kernel BUG at mm/huge_memory.c:1267! - mapcount 5 page_mapcount 4 [rhel-6.0.z]

Summary:	kernel BUG at mm/huge_memory.c:1267! - mapcount 5 page_mapcount 4 [rhel-6.0.z]

Status:	CLOSED ERRATA

Aliases:	None

Product:	Red Hat Enterprise Linux 6
Classification:	Red Hat
Component:	kernel (Show other bugs)
Sub Component:
Version:	6.0
Hardware:	All Linux

Priority	urgent Severity urgent
Target Milestone:	rc
Target Release:	---
Assigned To:	Frantisek Hrbata
QA Contact:	Chao Ye
Docs Contact:

URL:
Whiteboard:
Keywords:	ZStream

Depends On:	642570
Blocks:
	Show dependency tree / graph

Reported:	2010-10-18 15:11 EDT by Benjamin Kahn
Modified:	2010-11-11 06:56 EST (History)
CC List:	10 users (show)

See Also:
Fixed In Version:	kernel-2.6.32-71.5.1.el6
Doc Type:	Bug Fix
Doc Text:	The fork() system call led to an rmap walk finding the parent huge-pmd twice instead of once, thus causing a discrepancy between the mapcount and page_mapcount check, which could have led to erratic page counts for subpages. This fix ensures that that the rmap walk is accurate when a process is forked, thus resolving the issue.
Story Points:	---
Clone Of:
Environment:
Last Closed:	2010-11-10 14:11:36 EST
Type:	---
Regression:	---
Mount Type:	---
Documentation:	---
CRM:
Verified Versions:
Category:	---
oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---

Attachments	(Terms of Use)
Add an attachment (proposed patch, testcase, etc.)

External Trackers
Tracker	ID	Priority	Status	Summary	Last Updated
Red Hat Product Errata	RHSA-2010:0842	normal	SHIPPED_LIVE	Important: kernel security and bug fix update	2010-11-22 14:34:20 EST

Groups: None (edit)

Description Benjamin Kahn 2010-10-18 15:11:41 EDT

This bug has been copied from bug #642570 and has been proposed
to be backported to 6.0 z-stream (EUS).

Comment 2 Frantisek Hrbata 2010-10-20 02:22:41 EDT

in 2.6.32-71.5.1.el6

Comment 4 QiangGao 2010-10-25 01:38:01 EDT

Confirm patch is included in 2.6.32-71.5.1.el6.x86_64

Comment 11 errata-xmlrpc 2010-11-10 14:11:36 EST

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-2010-0842.html

Comment 12 Martin Prpič 2010-11-11 06:56:50 EST

    Technical note added. If any revisions are required, please edit the "Technical Notes" field
    accordingly. All revisions will be proofread by the Engineering Content Services team.
    
    New Contents:
The fork() system call led to an rmap walk finding the parent huge-pmd twice instead of once, thus causing a discrepancy between the mapcount and page_mapcount check, which could have led to erratic page counts for subpages. This fix ensures that that the rmap walk is accurate when a process is forked, thus resolving the issue.

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