Bug 1427647 – [rt] dump stack: don't disable preemption during trace

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Bug 1427647 - [rt] dump stack: don't disable preemption during trace

Summary:	[rt] dump stack: don't disable preemption during trace

Status:	CLOSED ERRATA

Aliases:	None

Product:	Red Hat Enterprise Linux 7
Classification:	Red Hat
Component:	kernel-rt (Show other bugs)
Sub Component:
Version:	7.4
Hardware:	x86_64 Linux

Priority	low Severity medium
Target Milestone:	rc
Target Release:	---
Assigned To:	Luis Claudio R. Goncalves
QA Contact:	Jiri Kastner
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Depends On:
Blocks:	1353018 1410158
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Reported:	2017-02-28 15:03 EST by Clark Williams
Modified:	2017-08-01 20:24 EDT (History)
CC List:	2 users (show)

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Last Closed:	2017-08-01 15:00:29 EDT
Type:	Bug
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External Trackers
Tracker	ID	Priority	Status	Summary	Last Updated
Red Hat Product Errata	RHSA-2017:2077	normal	SHIPPED_LIVE	Important: kernel-rt security, bug fix, and enhancement update	2017-08-01 14:13:37 EDT

Groups: None (edit)

Description Clark Williams 2017-02-28 15:03:36 EST

We see large latencies during a stack dump on x86. The
preempt_disable() and get_cpu() should forbid moving the task to another
CPU during a stack dump and avoiding two stack traces in parallel on the
same CPU. However a stack trace from a second CPU may still happen in
parallel. Also nesting is allowed so a stack trace happens in
process-context and we may have another one from IRQ context. With migrate
disable we keep this code preemptible and allow a second backtrace on
the same CPU by another task.

Comment 7 errata-xmlrpc 2017-08-01 15:00:29 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-2017:2077

Comment 8 errata-xmlrpc 2017-08-01 20:24:28 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-2017:2077

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