From owner-freebsd-hackers@freebsd.org Wed Feb 14 09:06:20 2018 Return-Path: Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 69207F0F12B for ; Wed, 14 Feb 2018 09:06:20 +0000 (UTC) (envelope-from killing@multiplay.co.uk) Received: from mail-wr0-x230.google.com (mail-wr0-x230.google.com [IPv6:2a00:1450:400c:c0c::230]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id DF4F86C5D4 for ; Wed, 14 Feb 2018 09:06:19 +0000 (UTC) (envelope-from killing@multiplay.co.uk) Received: by mail-wr0-x230.google.com with SMTP id v65so14552319wrc.11 for ; Wed, 14 Feb 2018 01:06:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=multiplay-co-uk.20150623.gappssmtp.com; s=20150623; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-language; bh=siex4p9VSEgejp0hBXrBw5AzZ8jIc/xzlFf9xXe51/A=; b=Z3BfKSn7QHTHIeiecCXdmBY2GPF28Z3bRZJEmHRZiFDFqp5LcGtj5lvd4Y6CXd0Jig X0LcoCw8+R8T1ESmZ+eJIKaIUUeKIUFQ2Rq+x9lj5YwmU0p09fRZ1WWO05tTeLNLAYlM V+Fk9Fh84FI2o/YO5dnVXgdJ3b9jxGZFCYkuXvXQAFsdBO/Z7lSoOL6SMbZBkTjiGHuK LBzVqpr6QfPkMsnL1qTvsbyJAqiU5Umcf01sxFLK4ISH2XnmA1uVbRNEfbsUMKJZ/P4J gv2bOwhNP9bwSxjn/2xMqbA8NItc0dsbNHF2PBdoYtwvt3uklgujkQclrlcoQnehzWRQ YMzA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language; bh=siex4p9VSEgejp0hBXrBw5AzZ8jIc/xzlFf9xXe51/A=; b=HNPYt4U4XB/sjNbA/k4zxP8plINQtBxTuh2XM8BbAW1ZYTsqV72AgYbxbbhrClhl7w gBI7fqBsWS0/HxDyND25rdpRz0dh1Xpsoj0ed8jK40LnmsV3uXTcLocCmrwR8l22sxiR GTW+ML5ZSiscnjIB7bRBerxiR9Ngv/IonOFmcnBMMFOOfMp47GQ3Z1+NUqxp5/2fYwR+ 6NiUSLhW9Ug8bn1r4ZNA6vhE9U49Fvzy6uZr0ZusAqxESpLsqtmm8UrFWvbcePN7FkuL XS2jPIyCpYoJuob0D8npFASCUhvW7pFhaKIP57LjVkVGyCcnqJygxcTimq/VEnYbRbOU 0E0w== X-Gm-Message-State: APf1xPA/9G19oxTMgr0OXoPOlI7s2/KRkonBfte2jZrLfOhdGvQvapYp diMzzXzv8q9tae1nlkcLOVt7EjqMfa4= X-Google-Smtp-Source: AH8x226XgU2qS9NhylSzO//aJM2RPKcYU6+x4O5iD5Qr2RvHjmZurvvzx1JbLzknJO7Rk9t05QSQZQ== X-Received: by 10.223.162.220 with SMTP id t28mr3601543wra.220.1518599178227; Wed, 14 Feb 2018 01:06:18 -0800 (PST) Received: from [10.10.1.111] ([185.97.61.1]) by smtp.gmail.com with ESMTPSA id t4sm10060757wmt.16.2018.02.14.01.06.16 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 14 Feb 2018 01:06:16 -0800 (PST) Subject: Re: Stale memory during post fork cow pmap update To: freebsd-hackers@freebsd.org 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> From: Steven Hartland Message-ID: <16f4ce10-70d3-12f4-2246-e8ab44ba511f@multiplay.co.uk> Date: Wed, 14 Feb 2018 09:06:18 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.25 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 14 Feb 2018 09:06:20 -0000 @kib do you think this issue could be the cause of the golang crashes during fork that we spoke about a while back https://github.com/golang/go/issues/15658 If its possible is there anything specific I could do to force a regular occurrence in order to confirm or deny it? On 13/02/2018 21:49, Mike Tancsa wrote: > 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 > >