From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1521827346; cv=none; d=google.com; s=arc-20160816; b=JeeFGaOprqApt/WtqnnRsKFun/O9APMg9B1WWnRpiM0VEbNJ9X5SBEMJj4eh8wgpe0 0sHtVHSuy6CYFfnf3mtogtf3m72QwFD2KMz/K7WhCYFLtIgAB9BjxFji9O5kB6ekz19y A1/IhsmDizwC96hkN6YtsNDfxRrEm57+aBac1Rx8uhuEZbVffPf5UQ9gsSaMJf9FkqhT tQ69mLL6RVi+o+/yfAiNEMEihsCdWz8ELwI/lwnfXCqv1/ECI3bWuu/4e1VjyNKWC62c ggslociYk/jxUGlwWQ+3VZINFP/9aFc9a0Tpmaikx5ZJB2jMIF2Oiiaph78/X1ig5sK0 dojA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=to:references:message-id:content-transfer-encoding:cc:date :in-reply-to:from:subject:mime-version:dkim-signature :arc-authentication-results; bh=jQmHZjnJbgzm5Bnta7AxMgcjy2Bp3CXXFf+gGk9Ctfs=; b=CO+OT+RvMy7k9KiUoA932qilqjInumGRapTtlyJxuQM0upXhrir7xqdxsd3nvu8DLl yfRNeA1IH28GTIFO8C45EQiZf7KDf6yoMJ8RWDAvg5jcC7KR69eoHaRdtKiBbviBNNet YFbWIwf2hStRFJlIS+lCAlB2azN0pXIPKvsfvNMmQuiG+Jl1pt1SBZ7Ry9n3zGA7kInE fFQkZRmUwRAIVx6PZTaSHwZxvDu11kKGU7lhr6apgma4Bwf/j1dU/E6xIsBTprYLQ95N 8b9xORT3+2A/rbDUujBDfGJiNhaExbEZGeYfGWzCSqEcjutnI58XSpPQofLKoMc7szDQ 5Ugg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=egpWFPxz; spf=pass (google.com: domain of blackzert@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=blackzert@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=egpWFPxz; spf=pass (google.com: domain of blackzert@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=blackzert@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com X-Google-Smtp-Source: AG47ELuRtAiE5GxJ4PVlasYQbBVUoZzWlqey9KsMKVVJwaWDGj31q8vofooz0Xfhmk8aYru+zAB7Aw== 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 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 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> To: Andrew Morton X-Mailer: Apple Mail (2.3445.5.20) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1595656493467338178?= X-GMAIL-MSGID: =?utf-8?q?1595751631673538172?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: > 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.=