Bug 1506255 – mm: print warning when ksmd thread runs with CONFIG_PREEMPT_RT enabled

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Bug 1506255 - mm: print warning when ksmd thread runs with CONFIG_PREEMPT_RT enabled

Summary:	mm: print warning when ksmd thread runs with CONFIG_PREEMPT_RT enabled

Status:	CLOSED ERRATA

Aliases:	None

Product:	Red Hat Enterprise Linux 7
Classification:	Red Hat
Component:	kernel-rt (Show other bugs)
Sub Component:
Version:	7.5
Hardware:	x86_64 Linux

Priority	unspecified Severity medium
Target Milestone:	rc
Target Release:	---
Assigned To:	Clark Williams
QA Contact:	Jiri Kastner
Docs Contact:

URL:
Whiteboard:
Keywords:

Depends On:
Blocks:	1442258
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Reported:	2017-10-25 09:38 EDT by Clark Williams
Modified:	2018-04-10 04:59 EDT (History)
CC List:	2 users (show)

See Also:
Fixed In Version:
Doc Type:	No Doc Update
Doc Text:	undefined
Story Points:	---
Clone Of:
Environment:
Last Closed:	2018-04-10 04:57:57 EDT
Type:	Bug
Regression:	---
Mount Type:	---
Documentation:	---
CRM:
Verified Versions:
Category:	---
oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---

Attachments	(Terms of Use)
rt: warn when KSM thread runs on PREEMPT_RT (913 bytes, patch) 2017-10-30 15:08 EDT, Clark Williams	no flags	Details \| Diff
Add an attachment (proposed patch, testcase, etc.)

External Trackers
Tracker	ID	Priority	Status	Summary	Last Updated
Red Hat Product Errata	RHSA-2018:0676	None	None	None	2018-04-10 04:59 EDT

Groups: None (edit)

Description Clark Williams 2017-10-25 09:38:59 EDT

Description of problem:

Kernel Same-page Merging (CONFIG_KSM) is a mechanism of reducing duplicated pages in the kernel and can reduce memory usage for some cases. Unfortunately the work required to scan physical pages for duplicate contents can result in latency spikes on a real time Linux kernel. 

To warn users of this potential, print a warning when ksmd is activated on a realtime kernel.

Comment 2 Clark Williams 2017-10-30 15:08 EDT

Created attachment 1345569 [details]
rt: warn when KSM thread runs on PREEMPT_RT

First cut at patch to warn when ksmd runs on RT

Comment 7 errata-xmlrpc 2018-04-10 04:57:57 EDT

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.

https://access.redhat.com/errata/RHSA-2018:0676

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