Bug 696998

Summary:	Check if PTE is already allocated during page fault
Product:	Red Hat Enterprise Linux 6	Reporter:	Andrea Arcangeli <aarcange>
Component:	kernel	Assignee:	Andrea Arcangeli <aarcange>
Status:	CLOSED ERRATA	QA Contact:	WANG Chao <chaowang>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	6.2	CC:	chaowang, czhang, kzhang, ruyang, tburke
Target Milestone:	rc
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	kernel-2.6.32-150.el6	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2011-12-06 13:10:24 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:

Description Andrea Arcangeli 2011-04-15 14:42:38 UTC

Description of problem: page fault could call __pte_alloc superflously


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


How reproducible: 100%


Steps to Reproduce:
1. Run AIM9 and check page_test performance (the fix improve performance 9%)

Comment 2 Andrea Arcangeli 2011-04-15 15:23:40 UTC

I submitted a new kernel build including this fix and experimental (but should be safe) mremap/mincore/mprotect optimizations for 6.2.

http://brewweb.devel.redhat.com/brew/taskinfo?taskID=3261556

Comment 3 Andrea Arcangeli 2011-04-27 13:12:51 UTC

I suggest to defer this to 6.2 and to reject the patch I posted to rhkernel-list because it's not so important for RHEL6 (because of some difference between memory.c in RHEL6 and upstream, for upstream it was much more important). However for 6.2 we should apply another patch that will make memory.c of RHEL6.2 in sync with upstream for this specific location. I posted it to rhkernel-list with Message-ID: <20110427131003.GG32590> . It's only for RHEL6.2 and the previous patch with Message-ID: <20110415152304.GR15707> we can forget it (it was a small valid improvement but not relevant enough for 6.1, so it's better to apply the new one only in 6.2).

Comment 4 RHEL Program Management 2011-05-13 15:23:20 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 5 Aristeu Rozanski 2011-05-18 19:49:30 UTC

Patch(es) available on kernel-2.6.32-150.el6

Comment 11 errata-xmlrpc 2011-12-06 13:10:24 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHSA-2011-1530.html