Date: Tue, 13 Feb 2018 16:49:08 -0500 From: Mike Tancsa <mike@sentex.net> To: Konstantin Belousov <kib@freebsd.org>, Elliott.Rabe@dell.com Cc: Eric.Van.Gyzen@dell.com, freebsd-hackers@freebsd.org, truckman@FreeBSD.org, markj@FreeBSD.org, alc@FreeBSD.org Subject: Re: Stale memory during post fork cow pmap update Message-ID: <aadcb842-fb07-e856-e525-2e562d5a9e2d@sentex.net> In-Reply-To: <20180213133010.GD94212@kib.kiev.ua> References: <5A7E7F2B.80900@dell.com> <20180210111848.GL33564@kib.kiev.ua> <5A7F6A7C.80607@dell.com> <20180210225608.GM33564@kib.kiev.ua> <5A82AB7C.6090404@dell.com> <20180213133010.GD94212@kib.kiev.ua>
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On 2/13/2018 8:30 AM, Konstantin Belousov wrote: > Apparently Ryzen CPUs are able to demonstrate it quite reliably with the > python driver for the samba build. It was very surprising to me, esp. > because I tried to understand the Ryzen bug for the whole last week and > thought that it is more likely CPU store/load inconsistency than a software > thing. See https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=225584. Just tested on an AMD EPYC 7281 (16/32 cores), and it runs into this bug every time on the samba build. Applying the referenced patch fixes the problem, at least I was able to test 4 builds in a row without issue. ---Mike -- ------------------- Mike Tancsa, tel +1 519 651 3400 x203 Sentex Communications, mike@sentex.net Providing Internet services since 1994 www.sentex.net Cambridge, Ontario Canada
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