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Bug 245042

Summary:	make new RHEL5 NFS symlink code use GFP_HIGHUSER for pagecache
Product:	Red Hat Enterprise Linux 5	Reporter:	Jeff Layton <jlayton>
Component:	kernel	Assignee:	Jeff Layton <jlayton>
Status:	CLOSED ERRATA	QA Contact:	Martin Jenner <mjenner>
Severity:	low	Docs Contact:
Priority:	low
Version:	5.0	CC:	coughlan, staubach, steved
Target Milestone:	---
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	RHBA-2008-0314	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2008-05-21 14:44:32 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:	425461

Description Jeff Layton 2007-06-20 17:49:22 UTC

The patch for bug 218718 makes it so that nfs_symlink() allocates a page
destined for pagecache and uses that to hold the name to which the symlink
points. It allocates it using this:

page = alloc_page(GFP_KERNEL);

...but most pagecache pages are allocated using GFP_HIGHUSER. There's no reason
to use normal zone memory for this.

I pushed a patch upstream recently to change this to use GFP_HIGHUSER, but it's
not shown up in Trond's tree or mainline yet. I'd like this to go upstream for a
bit to make sure there are no issues, but eventually we should consider pulling
this back for RHEL5 (maybe for 5.2).

Comment 1 RHEL Program Management 2007-08-22 12:57:02 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 2 Jeff Layton 2007-09-13 15:43:36 UTC

Not sure how best to QA this...

It'll probably come down to installing a 32 bit machine with a large amount of
memory (>1G or so), writing script that creates a ton of symlinks on a NFS
mount, and watching memory statistics as it runs.

Without this patch, normal zone memory should drop much more quickly, while with
this patch, more of these pages should come out of highmem.

Comment 5 Don Zickus 2007-12-14 18:38:35 UTC

in 2.6.18-60.el5
You can download this test kernel from http://people.redhat.com/dzickus/el5

Comment 8 errata-xmlrpc 2008-05-21 14:44:32 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/RHBA-2008-0314.html