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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 C3D89C2BBFD for ; Fri, 10 Apr 2020 02:38:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9C58E20A8B for ; Fri, 10 Apr 2020 02:38:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="AVSNgz0e" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726637AbgDJCiv (ORCPT ); Thu, 9 Apr 2020 22:38:51 -0400 Received: from mail-pl1-f194.google.com ([209.85.214.194]:32887 "EHLO mail-pl1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725987AbgDJCiu (ORCPT ); Thu, 9 Apr 2020 22:38:50 -0400 Received: by mail-pl1-f194.google.com with SMTP id ay1so234785plb.0; Thu, 09 Apr 2020 19:38:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=cm3qEVUblIBWQEP7R8pxH+eUa0WNyfWiM9J7eM+Fwmk=; b=AVSNgz0eR/mu36t1jtB1pHxzPsuhsLJ5Dgmcn/9c7jPOTV+CNdcyL0zkXP7nLHQzQV A10fzku8OWDIGvjGdvgdeH+jWjXzrllDIeVhKdprzXhQynX714rs3Td/tjGR+coEL5Aw 9O9rN2XFZJ5QvZNpH7rO2zchnfDG/1aaYCeqb4UwllljqxtOrpvrRcKDBEk9COBYQQFO 1jJAN0Hms3ovic+Bal9KAkQ1W5BRhoTGfKl7mwDWNfIHMcC8IP7152Er0GK1ixcZQijG 71dIgnkhRybaZPDMrOAJ7jaWMDsjZpbv/oC14bGuigw82SaeZ2oRTYvVKah0eRNKXHb0 NEUg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:date:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=cm3qEVUblIBWQEP7R8pxH+eUa0WNyfWiM9J7eM+Fwmk=; b=GvUX1EMRNMGonWMDs6sl6S6tHfxa1eH2Pdx/Y8Wu1mWhfQ6khksEs1m+T9jE9kqE8u gWv+F+cvKljaPfjuo5AE48O/yTmhzM2no0LblUDqUJMF3tT2ZC8Fo8tcVpfcGduKXy9z qrr1VQ/q/BzSXrQBCSuczL6htWzih5ulw2FmEJdMudcqaVuGNn1ZPrvfSoYXlmA5P8SG 7ywxFF2MSi5O3igE+YnCRCFFZCk071L23YwRx6qB/1d+NH2teJCtwaw6GR8KZlJ4nmrL 7YHfPUjX1KHrTN4XdotQLprgHcbBgIi7sCSx3qr1FcW2WB8tL7w1NCMnOcpl0nl94mYa roJQ== X-Gm-Message-State: AGi0PuY8bkPmAxijXmFIsqz3eeoYDsGpLBunDFu88olYd5rH7IP1/NHU mOWJjbrJBuBU8kj43o9FWls= X-Google-Smtp-Source: APiQypJUNzW2Kf/YisQ7Gm6MjGoHraf0uboGBOm6Ai9D7kmeIiXDGo0t/+GLEITvv65wjz5MhoeSGg== X-Received: by 2002:a17:90a:628c:: with SMTP id d12mr2775900pjj.53.1586486329072; Thu, 09 Apr 2020 19:38:49 -0700 (PDT) Received: from localhost (181.56.30.125.dy.iij4u.or.jp. [125.30.56.181]) by smtp.gmail.com with ESMTPSA id f4sm456109pjm.9.2020.04.09.19.38.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Apr 2020 19:38:48 -0700 (PDT) From: Sergey Senozhatsky X-Google-Original-From: Sergey Senozhatsky Date: Fri, 10 Apr 2020 11:38:45 +0900 To: Minchan Kim Cc: Peter Zijlstra , Christoph Hellwig , Andrew Morton , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Wei Liu , x86@kernel.org, David Airlie , Daniel Vetter , Laura Abbott , Sumit Semwal , Sakari Ailus , Nitin Gupta , Robin Murphy , Christophe Leroy , linuxppc-dev@lists.ozlabs.org, linux-hyperv@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, sergey.senozhatsky@gmail.com Subject: Re: [PATCH 10/28] mm: only allow page table mappings for built-in zsmalloc Message-ID: <20200410023845.GA2354@jagdpanzerIV.localdomain> References: <20200408115926.1467567-1-hch@lst.de> <20200408115926.1467567-11-hch@lst.de> <20200409160826.GC247701@google.com> <20200409165030.GG20713@hirez.programming.kicks-ass.net> <20200409170813.GD247701@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200409170813.GD247701@google.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (20/04/09 10:08), Minchan Kim wrote: > > > Even though I don't know how many usecase we have using zsmalloc as > > > module(I heard only once by dumb reason), it could affect existing > > > users. Thus, please include concrete explanation in the patch to > > > justify when the complain occurs. > > > > The justification is 'we can unexport functions that have no sane reason > > of being exported in the first place'. > > > > The Changelog pretty much says that. > > Okay, I hope there is no affected user since this patch. > If there are someone, they need to provide sane reason why they want > to have zsmalloc as module. I'm one of those who use zsmalloc as a module - mainly because I use zram as a compressing general purpose block device, not as a swap device. I create zram0, mkfs, mount, checkout and compile code, once done - umount, rmmod. This reduces the number of writes to SSD. Some people use tmpfs, but zram device(-s) can be much larger in size. That's a niche use case and I'm not against the patch. -ss