From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ilya Smith Date: Fri, 23 Mar 2018 17:49:03 +0000 Subject: Re: [RFC PATCH v2 2/2] Architecture defined limit on memory region random shift. Message-Id: <548B6BB8-FD6F-4F8D-B67F-2809305C617D@gmail.com> List-Id: References: <1521736598-12812-1-git-send-email-blackzert@gmail.com> <1521736598-12812-3-git-send-email-blackzert@gmail.com> <20180322135448.046ada120ecd1ab3dd8f94aa@linux-foundation.org> In-Reply-To: <20180322135448.046ada120ecd1ab3dd8f94aa@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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: > > > 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.