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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham 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 42F7EC46475 for ; Tue, 23 Oct 2018 21:02:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E4FD920671 for ; Tue, 23 Oct 2018 21:02:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="b8RamXei" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E4FD920671 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=joelfernandes.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727662AbeJXF1G (ORCPT ); Wed, 24 Oct 2018 01:27:06 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:38085 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725948AbeJXF1G (ORCPT ); Wed, 24 Oct 2018 01:27:06 -0400 Received: by mail-pl1-f195.google.com with SMTP id p7-v6so1198610plk.5 for ; Tue, 23 Oct 2018 14:02:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=p4FMNdBUY2JIhPzCQXL/Z3eiqadkxTMsq0q0z4hPidU=; b=b8RamXeiIAulFDaK/Ra11q92Q2Kqx89nKa8pCsPZ+AthXq2dYYfr/mAZZYgxQzitbW IGU4rc2o/j8f84QhhaaB56ldjp98sdFUapkMnhxM1qL64ZwrCKrXui7T0EkBCyTh2SBg x6zuGCqYQM41MWfdpovemA/VhaOAKYZsYlIbc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=p4FMNdBUY2JIhPzCQXL/Z3eiqadkxTMsq0q0z4hPidU=; b=pPZk9Zf4BD1z55lvOptrbQFkayPS41ozpNhjIm+L4IVmS57j+UrsbleMglu4uH8c2J Kg2xaGsEnzW0NwY/VuDxcMbi4jVfer6lQIbPkSbi3hUfRrDa9N7by+u7YWSDMAns+n5R nE9p+bV7VNBK4t5YeA1r4E95NiQMAaHMY76s9r4e1KaXwPYW47k0Gi94hAIzdP0v33v6 63jNpUFKWi2I9vweAY5DQNukriXDDkOgY3jEOwMSFkjT4TWIu9e2u/yFnfdm5drAhTc9 q+yTPls/bzr7QAQ8ycKwNleR9n6ErvgYrGeWXu91FKmwKm5kiHPD4pHOAGpMZSVMXfbY qUZg== X-Gm-Message-State: ABuFfojFJ3ojY0tr1cJFABqn2EMzItJ7rnd/1xJIoxQVIbvtJDmduuaZ DrKmrdAMb1w+4o0CNfo8svAOL6EXkw0= X-Google-Smtp-Source: ACcGV62D3gldGIjcU7ddc4A/XCvT+x/BnFAS+O8FKsmdDEKf9VQ/2HP1gBraVP14Y8KznV6Wcj0K+A== X-Received: by 2002:a17:902:5602:: with SMTP id h2-v6mr49445624pli.220.1540328520738; Tue, 23 Oct 2018 14:02:00 -0700 (PDT) Received: from localhost ([2620:0:1000:1601:3aef:314f:b9ea:889f]) by smtp.gmail.com with ESMTPSA id p24-v6sm8198019pgm.70.2018.10.23.14.01.58 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 23 Oct 2018 14:01:59 -0700 (PDT) Date: Tue, 23 Oct 2018 14:01:58 -0700 From: Joel Fernandes To: Matthew Wilcox Cc: Shuah Khan , Michal Hocko , Uladzislau Rezki , Kees Cook , Andrew Morton , linux-mm@kvack.org, LKML , Thomas Garnier , Oleksiy Avramchenko , Steven Rostedt , Joel Fernandes , Thomas Gleixner , Ingo Molnar , Tejun Heo , maco@android.com Subject: Re: [RFC PATCH 0/2] improve vmalloc allocation Message-ID: <20181023210158.GA229730@joelaf.mtv.corp.google.com> References: <20181022125142.GD18839@dhcp22.suse.cz> <20181022165253.uphv3xzqivh44o3d@pc636> <20181023072306.GN18839@dhcp22.suse.cz> <20181023152640.GD20085@bombadil.infradead.org> <20181023170532.GW18839@dhcp22.suse.cz> <98842edb-d462-96b1-311f-27c6ebfc108a@kernel.org> <20181023193044.GA139403@joelaf.mtv.corp.google.com> <024af44a-77e1-1c61-c9b2-64ffbe4f7c49@kernel.org> <20181023200923.GB25444@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181023200923.GB25444@bombadil.infradead.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 23, 2018 at 01:09:23PM -0700, Matthew Wilcox wrote: > On Tue, Oct 23, 2018 at 01:48:32PM -0600, Shuah Khan wrote: > > On 10/23/2018 01:30 PM, Joel Fernandes wrote: > > > On Tue, Oct 23, 2018 at 11:13:36AM -0600, Shuah Khan wrote: > > >> I like this proposal. I think we will open up lot of test opportunities with > > >> this approach. > > >> > > >> Maybe we can use this stress test as a pilot and see where it takes us. > > > > > > I am a bit worried that such an EXPORT_SYMBOL_KSELFTEST mechanism can be abused by > > > out-of-tree module writers to call internal functionality. > > > > That is valid concern to consider before we go forward with the proposal. > > > > We could wrap EXPORT_SYMBOL_KSELFTEST this in an existing debug option. This could > > be fine grained for each sub-system for its debug option. We do have a few of these > > now > > This all seems far more complicated than my proposed solution. Matthew's solution seems Ok to me where it works. A problem could be that it will not always work. As an example, recently I wanted to directly set the sysctl_sched_rt_runtime variable from the rcutorture test, just for forcing some conditions. This symbol is internal and inaccessible from modules. This can also be done by calling the internal sched_rt_handler with some parameters. However I don't think including an internal source file in a test source file can achieve the objective of setting it since access to the internal symbol is not possible without exporting it somehow. This could be a "special" case too but is an example where the include trick may fall apart. I do think its a cool trick though ;-) - Joel