From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f70.google.com (mail-lf0-f70.google.com [209.85.215.70]) by kanga.kvack.org (Postfix) with ESMTP id 59F686B0009 for ; Fri, 23 Mar 2018 13:48:05 -0400 (EDT) Received: by mail-lf0-f70.google.com with SMTP id p202-v6so4186092lfe.3 for ; Fri, 23 Mar 2018 10:48:05 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id t17sor2445612lja.82.2018.03.23.10.48.03 for (Google Transport Security); Fri, 23 Mar 2018 10:48:04 -0700 (PDT) From: Ilya Smith Message-Id: <5D55B1FC-1962-4941-BF56-1F83554FC64C@gmail.com> Content-Type: multipart/signed; boundary="Apple-Mail=_B9437F76-CEDD-4524-828D-E63FF8E38C7F"; protocol="application/pgp-signature"; micalg=pgp-sha256 Mime-Version: 1.0 (Mac OS X Mail 11.2 \(3445.5.20\)) Subject: Re: [RFC PATCH v2 2/2] Architecture defined limit on memory region random shift. Date: Fri, 23 Mar 2018 20:48:00 +0300 In-Reply-To: <20180322135448.046ada120ecd1ab3dd8f94aa@linux-foundation.org> References: <1521736598-12812-1-git-send-email-blackzert@gmail.com> <1521736598-12812-3-git-send-email-blackzert@gmail.com> <20180322135448.046ada120ecd1ab3dd8f94aa@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, vgupta@synopsys.com, linux@armlinux.org.uk, tony.luck@intel.com, fenghua.yu@intel.com, ralf@linux-mips.org, jejb@parisc-linux.org, Helge Deller , benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, nyc@holomorphy.com, viro@zeniv.linux.org.uk, arnd@arndb.de, gregkh@linuxfoundation.org, deepa.kernel@gmail.com, Michal Hocko , Hugh Dickins , kstewart@linuxfoundation.org, pombredanne@nexb.com, steve.capper@arm.com, punit.agrawal@arm.com, aneesh.kumar@linux.vnet.ibm.com, npiggin@gmail.com, Kees Cook , bhsharma@redhat.com, riel@redhat.com, nitin.m.gupta@oracle.com, "Kirill A. Shutemov" , Dan Williams , Jan Kara , ross.zwisler@linux.intel.com, Jerome Glisse , Matthew Wilcox , Andrea Arcangeli , Oleg Nesterov , linux-alpha@vger.kernel.org, LKML , linux-snps-arc@lists.infradead.org, linux-ia64@vger.kernel.org, linux-metag@vger.kernel.org, linux-mips@linux-mips.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, Linux-MM --Apple-Mail=_B9437F76-CEDD-4524-828D-E63FF8E38C7F Content-Type: multipart/alternative; boundary="Apple-Mail=_302D41D8-B8D8-4A57-A90C-AE132EC44462" --Apple-Mail=_302D41D8-B8D8-4A57-A90C-AE132EC44462 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii > On 22 Mar 2018, at 23:54, Andrew Morton = wrote: >=20 >=20 > Please add changelogs. An explanation of what a "limit on memory > region random shift" is would be nice ;) Why does it exist, why are we > doing this, etc. Surely there's something to be said - at present = this > is just a lump of random code? >=20 Sorry, my bad. The main idea of this limit is to decrease possible = memory fragmentation. This is not so big problem on 64bit process, but really = big for 32 bit processes since may cause failure memory allocation. To control = memory fragmentation and protect 32 bit systems (or architectures) this limit = was introduce by this patch. It could be also moved to CONFIG_ as well. --Apple-Mail=_302D41D8-B8D8-4A57-A90C-AE132EC44462 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii
On = 22 Mar 2018, at 23:54, Andrew Morton <akpm@linux-foundation.org> wrote:


Please add changelogs.  An explanation of what a "limit = on memory
region random shift" is would be nice ;) Why = does it exist, why are we
doing this, etc.  Surely = there's something to be said - at present this
is just a = lump of random code?

Sorry, = my bad. The main idea of this limit is to decrease possible = memory 
fragmentation. This is not so big problem on 64bit process, = but really big for 
32 bit = processes since may cause failure memory allocation. To control = memory 
fragmentation and protect 32 bit systems (or architectures) = this limit was 
introduce= by this patch. It could be also moved to CONFIG_ as = well.


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