Bug 1536370 – If IRQ disappears and reappears later the IRQ is not balanced correctly due to overflow in irq_count

Bugzilla will be upgraded to version 5.0 on a still to be determined date in the near future. The original upgrade date has been delayed.

Bug 1536370 - If IRQ disappears and reappears later the IRQ is not balanced correctly due to overflow in irq_count

Summary:	If IRQ disappears and reappears later the IRQ is not balanced correctly due t...

Status:	CLOSED ERRATA

Aliases:	None

Product:	Red Hat Enterprise Linux 6
Classification:	Red Hat
Component:	irqbalance (Show other bugs)
Sub Component:
Version:	6.7
Hardware:	Unspecified Unspecified

Priority	urgent Severity high
Target Milestone:	rc
Target Release:	---
Assigned To:	Petr Oros
QA Contact:	Evan McNabb
Docs Contact:	Petr Bokoc

URL:
Whiteboard:
Keywords:	ZStream

Depends On:
Blocks:	1536373 1541290 1541293
	Show dependency tree / graph

Reported:	2018-01-19 04:14 EST by Welterlen Benoit
Modified:	2018-09-18 05:01 EDT (History)
CC List:	7 users (show)

See Also:
Fixed In Version:	irqbalance-1.0.7-9.el6
Doc Type:	Bug Fix
Doc Text:	Previously, if a device disappeared and then reappeared, the "irq_count" interrupt request (IRQ) counter in irqbalance overflowed, which resulted in a failure to balance IRQs. This update adds a check which triggers a rescan of the IRQ database if the counter decreases. As a result, IRQs remain correctly balanced for disappearing and reappearing devices.
Story Points:	---
Clone Of:
Clones:	1536373 1541290 1541293 (view as bug list)
Environment:
Last Closed:	2018-06-19 01:19:19 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)
Add an attachment (proposed patch, testcase, etc.)

External Trackers
Tracker	ID	Priority	Status	Summary	Last Updated
Red Hat Knowledge Base (Solution)	3366621	None	None	None	2018-03-14 19:37 EDT
Red Hat Product Errata	RHBA-2018:1896	None	None	None	2018-06-19 01:19 EDT

Groups: None (edit)

Description Welterlen Benoit 2018-01-19 04:14:43 EST

Description of problem:

If IRQ disappears and reappears later the IRQ is not balanced correctly due to overflow in irq_count (as the counter got smaller and difference cause overflow).
Rescan if this happens fix the problem.

Version-Release number of selected component (if applicable):
irqbalance-1.0.7-8

How reproducible:
Reproducible when a device disappears and reappears, for example when vm has high network load on aws vms with an enavf device

Steps to Reproduce:
1. Make a device disappears and reappears
2.
3.

Actual results:
the IRQ is not balanced correctly when a device disappears and reappears


Expected results:
the IRQ is balanced correctly


Additional info:
ENA driver resets look like they deassign and reassign the IRQs thus resetting counts.
This is fixed in version 1.0.8 thanks to this patch "Balance correctly IRQs reappearing" :
https://github.com/Irqbalance/irqbalance/commit/93ed80181e0ce7b81bc88a67fabad1ad829fc460

Comment 14 errata-xmlrpc 2018-06-19 01:19:19 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/RHBA-2018:1896

Note You need to log in before you can comment on or make changes to this bug.