From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f43.google.com (mail-pa0-f43.google.com [209.85.220.43]) by kanga.kvack.org (Postfix) with ESMTP id 04AEB6B0038 for ; Mon, 23 Nov 2015 13:55:20 -0500 (EST) Received: by pacdm15 with SMTP id dm15so199428045pac.3 for ; Mon, 23 Nov 2015 10:55:19 -0800 (PST) Received: from mail-pa0-x22e.google.com (mail-pa0-x22e.google.com. [2607:f8b0:400e:c03::22e]) by mx.google.com with ESMTPS id xz3si21816582pbc.52.2015.11.23.10.55.19 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 23 Nov 2015 10:55:19 -0800 (PST) Received: by pabfh17 with SMTP id fh17so205361693pab.0 for ; Mon, 23 Nov 2015 10:55:19 -0800 (PST) Subject: Re: [PATCH v3 3/4] arm64: mm: support ARCH_MMAP_RND_BITS. References: <1447888808-31571-1-git-send-email-dcashman@android.com> <1447888808-31571-2-git-send-email-dcashman@android.com> <1447888808-31571-3-git-send-email-dcashman@android.com> <1447888808-31571-4-git-send-email-dcashman@android.com> <20151123150459.GD4236@arm.com> From: Daniel Cashman Message-ID: <56536114.1020305@android.com> Date: Mon, 23 Nov 2015 10:55:16 -0800 MIME-Version: 1.0 In-Reply-To: <20151123150459.GD4236@arm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Will Deacon Cc: linux-kernel@vger.kernel.org, linux@arm.linux.org.uk, akpm@linux-foundation.org, keescook@chromium.org, mingo@kernel.org, linux-arm-kernel@lists.infradead.org, corbet@lwn.net, dzickus@redhat.com, ebiederm@xmission.com, xypron.glpk@gmx.de, jpoimboe@redhat.com, kirill.shutemov@linux.intel.com, n-horiguchi@ah.jp.nec.com, aarcange@redhat.com, mgorman@suse.de, tglx@linutronix.de, rientjes@google.com, linux-mm@kvack.org, linux-doc@vger.kernel.org, salyzyn@android.com, jeffv@google.com, nnk@google.com, catalin.marinas@arm.com, hpa@zytor.com, x86@kernel.org, hecmargi@upv.es, bp@suse.de, dcashman@google.com On 11/23/2015 07:04 AM, Will Deacon wrote: > On Wed, Nov 18, 2015 at 03:20:07PM -0800, Daniel Cashman wrote: >> +config ARCH_MMAP_RND_BITS_MAX >> + default 20 if ARM64_64K_PAGES && ARCH_VA_BITS=39 >> + default 24 if ARCH_VA_BITS=39 >> + default 23 if ARM64_64K_PAGES && ARCH_VA_BITS=42 >> + default 27 if ARCH_VA_BITS=42 >> + default 29 if ARM64_64K_PAGES && ARCH_VA_BITS=48 >> + default 33 if ARCH_VA_BITS=48 >> + default 15 if ARM64_64K_PAGES >> + default 19 >> + >> +config ARCH_MMAP_RND_COMPAT_BITS_MIN >> + default 7 if ARM64_64K_PAGES >> + default 11 > > FYI: we now support 16k pages too, so this might need updating. It would > be much nicer if this was somehow computed rather than have the results > all open-coded like this. Yes, I ideally wanted this to be calculated based on the different page options and VA_BITS (which itself has a similar stanza), but I don't know how to do that/if it is currently supported in Kconfig. This would be even more desirable with the addition of 16K_PAGES, as with this setup we have a combinatorial problem. We could move this logic into the code where min/max are initialized, but that would create its own mess, creating new Kconfig values to introduce it in an arch-agnostic way after patch-set v2 moved that to mm/mmap.c instread of arch/${arch}/mm/mmap.c Suggestions welcome. Thank You, Dan -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org