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List:       freebsd-ia64
Subject:    ia64/147501: [ia64] options PREEMPTION causes instability
From:       Marcel Moolenaar <marcel () freebsd ! org>
Date:       2010-06-05 16:55:04
Message-ID: 201006051655.o55Gt4Pp041845 () www ! freebsd ! org
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> Number:         147501
> Category:       ia64
> Synopsis:       [ia64] options PREEMPTION causes instability
> Confidential:   no
> Severity:       serious
> Priority:       medium
> Responsible:    freebsd-ia64
> State:          open
> Quarter:        
> Keywords:       
> Date-Required:
> Class:          sw-bug
> Submitter-Id:   current-users
> Arrival-Date:   Sat Jun 05 17:00:16 UTC 2010
> Closed-Date:
> Last-Modified:
> Originator:     Marcel Moolenaar
> Release:        9-CURRENT
> Organization:
> Environment:
FreeBSD hob.lan.xcllnt.net 9.0-CURRENT FreeBSD 9.0-CURRENT #1 r208634:208809M: Sat \
Jun  5 08:36:47 PDT 2010     \
marcel@hob.lan.xcllnt.net:/usr/obj/nfs/freebsd/base/head/sys/HOB  ia64

> Description:
Running pho's stress2 with PREEMPTION results in kernel panics that are not seen when \
PREEMPTION is not enabled. This is with a SMP kernel.
> How-To-Repeat:
On a Montecito box:
o   checkout projects/stress2
o   compile and run
o   Wait for a panic (possibly a hard hang) within a few hours.

NOTE: Due to another bug, Montecito is the more reliable test platform.

> Fix:
Problem areas that are at the top of my head:
o   The weak memory ordering could result in race conditions if memory fences aren't \
properly used o   Access to PCPU fields is non-atomic, which may result in getting \
the wrong field when the thread migrates to another CPU in the middle of the access \
sequence.


> Release-Note:
> Audit-Trail:
> Unformatted:
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