From owner-svn-src-all@freebsd.org Thu Jun 8 22:32:36 2017 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 59741D857E3; Thu, 8 Jun 2017 22:32:36 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from mail.baldwin.cx (bigwig.baldwin.cx [96.47.65.170]) (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 2E0A974AD9; Thu, 8 Jun 2017 22:32:35 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from ralph.baldwin.cx (c-73-231-226-104.hsd1.ca.comcast.net [73.231.226.104]) by mail.baldwin.cx (Postfix) with ESMTPSA id E09D710AB01; Thu, 8 Jun 2017 18:32:33 -0400 (EDT) From: John Baldwin To: Alan Cox Cc: Bryan Drewery , src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r319702 - head/sys/vm Date: Thu, 08 Jun 2017 15:28 -0700 Message-ID: <1987063.fEClCI1ZXD@ralph.baldwin.cx> User-Agent: KMail/4.14.10 (FreeBSD/11.0-STABLE; KDE/4.14.10; amd64; ; ) In-Reply-To: <207FB492-94EE-47FD-BFB8-18F76C5858A5@rice.edu> References: <201706081618.v58GIfZi066106@repo.freebsd.org> <6910627.IXO0pzjk4q@ralph.baldwin.cx> <207FB492-94EE-47FD-BFB8-18F76C5858A5@rice.edu> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.4.3 (mail.baldwin.cx); Thu, 08 Jun 2017 18:32:34 -0400 (EDT) X-Virus-Scanned: clamav-milter 0.99.2 at mail.baldwin.cx X-Virus-Status: Clean X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 08 Jun 2017 22:32:36 -0000 On Thursday, June 08, 2017 05:07:40 PM Alan Cox wrote: >=20 > > On Jun 8, 2017, at 2:37 PM, John Baldwin wrote: > >=20 > > On Thursday, June 08, 2017 12:55:45 PM Bryan Drewery wrote: > >> On 6/8/17 12:18 PM, John Baldwin wrote: > >>> Author: jhb > >>> Date: Thu Jun 8 16:18:41 2017 > >>> New Revision: 319702 > >>> URL: https://svnweb.freebsd.org/changeset/base/319702 > >>>=20 > >>> Log: > >>> Fix an off-by-one error in the VM page array on some systems. > >>>=20 > >>> r31386 changed how the size of the VM page array was calculated = to be > >>> less wasteful.=20 > >>=20 > >> r313186 > >=20 > > Oops. FWIW, this commit fixes a reliable panic booting mips and mi= ps64 > > kernels under qemu. Adrian also reported the same panic on real mi= ps > > hardware. > >=20 >=20 > Any architecture on which we don=E2=80=99t have superpage reservation= s enabled could experience the panic at boot time. Amd64, arm, arm64, = i386, and sparc64 would never panic because of the memory allocated for= the reservation array.=20 Even then it seems to not be guaranteed. The original change has been in CheriBSD for a while, and we have not seen any panics on boot u= nder qemu as I saw with plain FreeBSD probably due to slightly different ear= ly memory allocations. --=20 John Baldwin