Date: 4 Jan 2011 11:05:23 -0000 From: Colin Percival <cperciva@FreeBSD.org> To: FreeBSD-gnats-submit@FreeBSD.org Subject: kern/153672: i386/XEN panics under heavy fork load Message-ID: <20110104110523.42568.qmail@xps.daemonology.net> Resent-Message-ID: <201101041110.p04BA9gF040060@freefall.freebsd.org>
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>Number: 153672
>Category: kern
>Synopsis: i386/XEN panics under heavy fork load
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Tue Jan 04 11:10:09 UTC 2011
>Closed-Date:
>Last-Modified:
>Originator: Colin Percival
>Release: FreeBSD 9.0-CURRENT i386/XEN
>Organization:
>Environment:
>Description:
Running 'make index', i386/XEN frequently panics. There are three
common backtraces:
vmspace_fork -> pmap_copy -> pmap_qenter
vmspace_fork -> pmap_copy -> pmap_zero_page
vmspace_fork -> pmap_pinit -> pmap_qenter
Notably, in every vmcore I've examined, a different thread was inside
pmap_release, suggesting that there is a race happening between
pmap_release and pmap_{copy, pinit}.
>How-To-Repeat:
Launch an EC2 instance running ami-f4db2a9d; portsnap fetch extract;
cd /usr/ports && make index.
On average there is one panic per 100 minutes.
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted:
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