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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B23B4C4332F for ; Thu, 7 Oct 2021 08:11:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 93676610CC for ; Thu, 7 Oct 2021 08:11:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240640AbhJGIMz (ORCPT ); Thu, 7 Oct 2021 04:12:55 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:51312 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240554AbhJGIMx (ORCPT ); Thu, 7 Oct 2021 04:12:53 -0400 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id E76371FF49; Thu, 7 Oct 2021 08:10:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1633594259; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Oc55QYscnPdKzwCjb0ywVfd/doUxkdVcTeLmeqISr7o=; b=M+pb6kZBKTijfupuQci9zI0JzzADDVtW/KDSipGnsBgM01o/2Zfd8Zf2qDwIDRzPapNAPw C/a15erqzs5+/vNjqXtbDZovG90WNGdDWv3/UjXvA8ptySXIDaLgqT+N+M30EdJqu5Rni2 QHhYCD82KKUdf/uvulrMMidepD6Q69c= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 43D35A3B85; Thu, 7 Oct 2021 08:10:59 +0000 (UTC) Date: Thu, 7 Oct 2021 10:10:58 +0200 From: Michal Hocko To: Suren Baghdasaryan Cc: Pavel Machek , David Hildenbrand , John Hubbard , Andrew Morton , Colin Cross , Sumit Semwal , Dave Hansen , Kees Cook , Matthew Wilcox , "Kirill A . Shutemov" , Vlastimil Babka , Johannes Weiner , Jonathan Corbet , Al Viro , Randy Dunlap , Kalesh Singh , Peter Xu , rppt@kernel.org, Peter Zijlstra , Catalin Marinas , vincenzo.frascino@arm.com, Chinwen Chang =?utf-8?B?KOW8temMpuaWhyk=?= , Axel Rasmussen , Andrea Arcangeli , Jann Horn , apopple@nvidia.com, Yu Zhao , Will Deacon , fenghua.yu@intel.com, thunder.leizhen@huawei.com, Hugh Dickins , feng.tang@intel.com, Jason Gunthorpe , Roman Gushchin , Thomas Gleixner , krisman@collabora.com, Chris Hyser , Peter Collingbourne , "Eric W. Biederman" , Jens Axboe , legion@kernel.org, Rolf Eike Beer , Cyrill Gorcunov , Muchun Song , Viresh Kumar , Thomas Cedeno , sashal@kernel.org, cxfcosmos@gmail.com, Rasmus Villemoes , LKML , linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm , kernel-team Subject: Re: [PATCH v10 3/3] mm: add anonymous vma name refcounting Message-ID: References: <20211005184211.GA19804@duo.ucw.cz> <20211005200411.GB19804@duo.ucw.cz> <6b15c682-72eb-724d-bc43-36ae6b79b91a@redhat.com> <20211006175821.GA1941@duo.ucw.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 06-10-21 11:18:31, Suren Baghdasaryan wrote: > On Wed, Oct 6, 2021 at 10:58 AM Pavel Machek wrote: [...] > > That "central facility" option can be as simple as "mkdir > > /somewhere/sanitized_id", using inode numbers for example. You don't > > really need IPC. > > Hmm, so the suggestion is to have some directory which contains files > representing IDs, each containing the string name of the associated > vma? Then let's say we are creating a new VMA and want to name it. We > would have to scan that directory, check all files and see if any of > them contain the name we want to reuse the same ID. I believe Pavel meant something as simple as $ YOUR_FILE=$YOUR_IDS_DIR/my_string_name $ touch $YOUR_FILE $ stat -c %i $YOUR_FILE YOUR_IDS_DIR can live on a tmpfs and you can even implement a policy on top of that (who can generate new ids, gurantee uniqness etc...). The above is certainly not for free of course but if you really need a system wide consistency when using names then you need some sort of central authority. How you implement that is not all that important but I do not think we want to handle that in the kernel. -- Michal Hocko SUSE Labs