Date: Fri, 21 Jan 2011 21:58:41 +0200 From: Kostik Belousov <kostikbel@gmail.com> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-hackers@freebsd.org, Sergey Kandaurov <pluknet@gmail.com> Subject: Re: [rfc] allow to boot with >= 256GB physmem Message-ID: <20110121195841.GA2518@deviant.kiev.zoral.com.ua> In-Reply-To: <201101211244.13830.jhb@freebsd.org> References: <AANLkTikt5=2L0rHyGbsjvG8eV6Ve4JkRM_pcyNiAsPu8@mail.gmail.com> <201101211244.13830.jhb@freebsd.org>
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--0w3sVzSwLDVzzp/e Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Jan 21, 2011 at 12:44:13PM -0500, John Baldwin wrote: > On Friday, January 21, 2011 11:09:10 am Sergey Kandaurov wrote: > > Hello. > >=20 > > Some time ago I faced with a problem booting with 400GB physmem. > > The problem is that vm.max_proc_mmap type overflows with > > such high value, and that results in a broken mmap() syscall. > > The max_proc_mmap value is a signed int and roughly calculated > > at vmmapentry_rsrc_init() as u_long vm_kmem_size quotient: > > vm_kmem_size / sizeof(struct vm_map_entry) / 100. > >=20 > > Although at the time it was introduced at svn r57263 the value > > was quite low (f.e. the related commit log stands: > > "The value defaults to around 9000 for a 128MB machine."), > > the problem is observed on amd64 where KVA space after > > r212784 is factually bound to the only physical memory size. > >=20 > > With INT_MAX here is 0x7fffffff, and sizeof(struct vm_map_entry) > > is 120, it's enough to have sligthly less than 256GB to be able > > to reproduce the problem. > >=20 > > I rewrote vmmapentry_rsrc_init() to set large enough limit for > > max_proc_mmap just to protect from integer type overflow. > > As it's also possible to live tune this value, I also added a > > simple anti-shoot constraint to its sysctl handler. > > I'm not sure though if it's worth to commit the second part. > >=20 > > As this patch may cause some bikeshedding, > > I'd like to hear your comments before I will commit it. > >=20 > > http://plukky.net/~pluknet/patches/max_proc_mmap.diff >=20 > Is there any reason we can't just make this variable and sysctl a long? I do not think we ever need 2G vm map entries in the single address space. --0w3sVzSwLDVzzp/e Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (FreeBSD) iEYEARECAAYFAk055XEACgkQC3+MBN1Mb4i18ACfRPoNewWV614iaSp+JkTffK5z CcMAoL2FLbg/0myY890cXtmiJFx0DUfQ =8A6Q -----END PGP SIGNATURE----- --0w3sVzSwLDVzzp/e--
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