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 06FE76B000A for ; Fri, 23 Mar 2018 13:49:08 -0400 (EDT) Received: by mail-lf0-f70.google.com with SMTP id r190-v6so4086152lfe.23 for ; Fri, 23 Mar 2018 10:49:07 -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 73-v6sor1292722lfz.85.2018.03.23.10.49.06 for (Google Transport Security); Fri, 23 Mar 2018 10:49:06 -0700 (PDT) Content-Type: text/plain; charset=us-ascii 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. From: Ilya Smith In-Reply-To: <20180322135448.046ada120ecd1ab3dd8f94aa@linux-foundation.org> Date: Fri, 23 Mar 2018 20:49:03 +0300 Content-Transfer-Encoding: quoted-printable Message-Id: <548B6BB8-FD6F-4F8D-B67F-2809305C617D@gmail.com> 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, jhogan@kernel.org, ralf@linux-mips.org, jejb@parisc-linux.org, deller@gmx.de, 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, mhocko@suse.com, hughd@google.com, kstewart@linuxfoundation.org, pombredanne@nexb.com, steve.capper@arm.com, punit.agrawal@arm.com, paul.burton@mips.com, aneesh.kumar@linux.vnet.ibm.com, npiggin@gmail.com, keescook@chromium.org, bhsharma@redhat.com, riel@redhat.com, nitin.m.gupta@oracle.com, kirill.shutemov@linux.intel.com, dan.j.williams@intel.com, jack@suse.cz, ross.zwisler@linux.intel.com, jglisse@redhat.com, willy@infradead.org, aarcange@redhat.com, oleg@redhat.com, linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@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@kvack.org > 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 >=20 >=20 Sorry, my bad. The main idea of this limit is to decrease possible = memory=20 fragmentation. This is not so big problem on 64bit process, but really = big for=20 32 bit processes since may cause failure memory allocation. To control = memory=20 fragmentation and protect 32 bit systems (or architectures) this limit = was=20 introduce by this patch. It could be also moved to CONFIG_ as well.=