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 X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C242FC433FE for ; Sun, 5 Sep 2021 13:04:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D5F8160F56 for ; Sun, 5 Sep 2021 13:04:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org D5F8160F56 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ucw.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 5786A900002; Sun, 5 Sep 2021 09:04:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 51E186B0072; Sun, 5 Sep 2021 09:04:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 40CB7900002; Sun, 5 Sep 2021 09:04:27 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0147.hostedemail.com [216.40.44.147]) by kanga.kvack.org (Postfix) with ESMTP id 2D98D6B0071 for ; Sun, 5 Sep 2021 09:04:27 -0400 (EDT) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id D30572BA9B for ; Sun, 5 Sep 2021 13:04:26 +0000 (UTC) X-FDA: 78553538532.29.2C186E0 Received: from jabberwock.ucw.cz (jabberwock.ucw.cz [46.255.230.98]) by imf25.hostedemail.com (Postfix) with ESMTP id 491F7B00008E for ; Sun, 5 Sep 2021 13:04:26 +0000 (UTC) Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id 59FEE1C0B77; Sun, 5 Sep 2021 15:04:23 +0200 (CEST) Date: Sun, 5 Sep 2021 15:04:18 +0200 From: Pavel Machek To: Kees Cook Cc: Suren Baghdasaryan , akpm@linux-foundation.org, ccross@google.com, sumit.semwal@linaro.org, mhocko@suse.com, dave.hansen@intel.com, willy@infradead.org, kirill.shutemov@linux.intel.com, vbabka@suse.cz, hannes@cmpxchg.org, corbet@lwn.net, viro@zeniv.linux.org.uk, rdunlap@infradead.org, kaleshsingh@google.com, peterx@redhat.com, rppt@kernel.org, peterz@infradead.org, catalin.marinas@arm.com, vincenzo.frascino@arm.com, chinwen.chang@mediatek.com, axelrasmussen@google.com, aarcange@redhat.com, jannh@google.com, apopple@nvidia.com, jhubbard@nvidia.com, yuzhao@google.com, will@kernel.org, fenghua.yu@intel.com, thunder.leizhen@huawei.com, hughd@google.com, feng.tang@intel.com, jgg@ziepe.ca, guro@fb.com, tglx@linutronix.de, krisman@collabora.com, chris.hyser@oracle.com, pcc@google.com, ebiederm@xmission.com, axboe@kernel.dk, legion@kernel.org, eb@emlix.com, gorcunov@gmail.com, songmuchun@bytedance.com, viresh.kumar@linaro.org, thomascedeno@google.com, sashal@kernel.org, cxfcosmos@gmail.com, linux@rasmusvillemoes.dk, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, kernel-team@android.com Subject: Re: [PATCH v9 2/3] mm: add a field to store names for private anonymous memory Message-ID: <20210905130418.GA7117@localhost> References: <20210902231813.3597709-1-surenb@google.com> <20210902231813.3597709-2-surenb@google.com> <202109031420.2F17A2C9@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <202109031420.2F17A2C9@keescook> User-Agent: Mutt/1.10.1 (2018-07-13) Authentication-Results: imf25.hostedemail.com; dkim=none; dmarc=none; spf=none (imf25.hostedemail.com: domain of pavel@ucw.cz has no SPF policy when checking 46.255.230.98) smtp.mailfrom=pavel@ucw.cz X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 491F7B00008E X-Stat-Signature: swwgd1p1sxgazcageajgk5dda6piznu6 X-HE-Tag: 1630847066-763528 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: Hi! > > the process is still running, so it has to have some sort of > > synchronization with every layer of userspace. Efficiently tracking > > the ranges requires reimplementing something like the kernel vma > > trees, and linking to it from every layer of userspace. It requires > > more memory, more syscalls, more runtime cost, and more complexity to > > separately track regions that the kernel is already tracking. Ok so far. > > This patch adds a field to /proc/pid/maps and /proc/pid/smaps to show a > > userspace-provided name for anonymous vmas. The names of named anonymous > > vmas are shown in /proc/pid/maps and /proc/pid/smaps as [anon:]. > > > > Userspace can set the name for a region of memory by calling > > prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, start, len, (unsigned > > long)name); Would setting a 64-bit integer instead of name be enough? Even if each party would set it randomly, risk of collisions would be very low... and we'd not have to deal with strings in kernel. Pavel --