From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id D88A4FA373D for ; Fri, 13 Sep 2024 10:21:23 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 115A06B00D1; Fri, 13 Sep 2024 06:21:23 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0C4B66B00D2; Fri, 13 Sep 2024 06:21:23 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E5A306B00D4; Fri, 13 Sep 2024 06:21:22 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id BF78A6B00D1 for ; Fri, 13 Sep 2024 06:21:22 -0400 (EDT) Received: from smtpin05.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 258B8A8264 for ; Fri, 13 Sep 2024 10:21:22 +0000 (UTC) X-FDA: 82559322804.05.96B95F7 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf19.hostedemail.com (Postfix) with ESMTP id 6980C1A0010 for ; Fri, 13 Sep 2024 10:21:20 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=none; spf=pass (imf19.hostedemail.com: domain of cmarinas@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=cmarinas@kernel.org; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=arm.com (policy=none) ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1726222827; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=JjivTjdDYEGFy4s4fXI/aZS3Cf4tpgLQCIGxve2BKbQ=; b=jUg1uusSI/OKQg892JAInrGTaJw1STnFAUklhbk/GnfQiNJaNIKC1HchgcV5QcEK97u0hk GG4Wm47Z0/8nDltmF6kTT7Cl12W0y41o91K2nFE9D4K3JeDTdUFquS3TtZW/FAMqKH3PWb QBWeQWSEgT0vMPMw8A5ZuzzQQQbyNiI= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=none; spf=pass (imf19.hostedemail.com: domain of cmarinas@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=cmarinas@kernel.org; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=arm.com (policy=none) ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1726222827; a=rsa-sha256; cv=none; b=wOIVoDn6fprpz+ID/rWe/+t6GPtn4srniJKr+lmbuKZPdMB8seLE9gkXRaKwIB3b4ZO0Oa 6VAhu8vwBsr72y6KGoQsH9bm4T9XEJz71XCKGFBVQsIba/C3pUoaAhw+3n+POlkuhTCNsU 8FhMcK7Mhru0fn5+nCcOMUmiGY9rtAQ= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 43ED05C5D13; Fri, 13 Sep 2024 10:21:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EFE3CC4CEC0; Fri, 13 Sep 2024 10:21:08 +0000 (UTC) Date: Fri, 13 Sep 2024 11:21:06 +0100 From: Catalin Marinas To: Charlie Jenkins Cc: "Liam R. Howlett" , Arnd Bergmann , guoren , Richard Henderson , Ivan Kokshaysky , Matt Turner , Vineet Gupta , Russell King , Huacai Chen , WANG Xuerui , Thomas Bogendoerfer , "James E . J . Bottomley" , Helge Deller , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Naveen N Rao , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , Yoshinori Sato , Rich Felker , John Paul Adrian Glaubitz , "David S . Miller" , Andreas Larsson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Muchun Song , Andrew Morton , Vlastimil Babka , Lorenzo Stoakes , shuah , Christoph Hellwig , Michal Hocko , "Kirill A. Shutemov" , Chris Torek , Linux-Arch , linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, "linux-csky@vger.kernel.org" , loongarch@lists.linux.dev, linux-mips@vger.kernel.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, linux-kselftest@vger.kernel.org, linux-abi-devel@lists.sourceforge.net Subject: Re: [PATCH RFC v3 1/2] mm: Add personality flag to limit address to 47 bits Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: 6980C1A0010 X-Stat-Signature: d8mrmfwxzfhq6emcp853irs9y8ntsaio X-HE-Tag: 1726222880-592874 X-HE-Meta: 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 7WD1t84K YwYTe1Lu2OKkA5AlcBO6a4EF7VyNc+bZNwkLGjMc9YYyBYBIHaefTK7dXQP5siV6sJVkANgDtL4jzbOZ12QhrWIP6VmxWWqUt5ymWZyEfmoG56BnyF+TFuChhR+SiLOJfcz93dbOzSfgpCXWr3h7FCKevg1MhzQS2V9TBSP9G5GMpWUBrlZx1VYN0WORChxUlP/wWH9B0B3EscVTeEcek51eLhnG7Wznne+M3rUJfUBJf+To4+iGBb69Kk1KBBuizQkKFOQL6SpgwAikKAtQHKU6+vXCHF66mwQEjV4RuOX1uUICAJAnCUQpq+CNlejpr5F7g6lc8995CLAcvnKzWUoY6ZIxrmS1eXBxXK+2e405ze6UC/uiQB6J1u0Pm6EIgLFhuEoxQYZWeynSaBvxB1kCtvEatxHuhvn6vSy3yxHv9IP/tjo1LcguqBsCvnrHcu+lpyBrlPCrFBE4= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Sep 13, 2024 at 11:08:23AM +0100, Catalin Marinas wrote: > On Thu, Sep 12, 2024 at 02:15:59PM -0700, Charlie Jenkins wrote: > > On Thu, Sep 12, 2024 at 11:53:49AM +0100, Catalin Marinas wrote: > > > On Wed, Sep 11, 2024 at 11:18:12PM -0700, Charlie Jenkins wrote: > > > > Opting-in to the higher address space is reasonable. However, it is not > > > > my preference, because the purpose of this flag is to ensure that > > > > allocations do not exceed 47-bits, so it is a clearer ABI to have the > > > > applications that want this guarantee to be the ones setting the flag, > > > > rather than the applications that want the higher bits setting the flag. [...] > Anyway, the prctl() can go both ways, either expanding or limiting the > default address space. So I'd be fine with such interface. Ah, I just realised (while reading Lorenzo's reply) that we can't really restrict the space via a prctl() as we have the main thread stack already allocated by the kernel before the user code starts. You may need to limit this stack as well, not just the later heap allocations (anonymous mmap()). -- Catalin