Date: Thu, 08 Jun 2017 15:28 -0700 From: John Baldwin <jhb@freebsd.org> To: Alan Cox <alc@rice.edu> Cc: Bryan Drewery <bdrewery@freebsd.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r319702 - head/sys/vm Message-ID: <1987063.fEClCI1ZXD@ralph.baldwin.cx> 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>
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On Thursday, June 08, 2017 05:07:40 PM Alan Cox wrote: >=20 > > On Jun 8, 2017, at 2:37 PM, John Baldwin <jhb@freebsd.org> 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
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