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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C8433C636CC for ; Tue, 31 Jan 2023 16:03:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231755AbjAaQD6 (ORCPT ); Tue, 31 Jan 2023 11:03:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42902 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231439AbjAaQDv (ORCPT ); Tue, 31 Jan 2023 11:03:51 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D933B49548 for ; Tue, 31 Jan 2023 08:03:46 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6ACD46151C for ; Tue, 31 Jan 2023 16:03:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CD990C4339B for ; Tue, 31 Jan 2023 16:03:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1675181025; bh=kUz3/3+6pALvgsc48sJBO2OS1e53UX0oL7m8fy1FZvI=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=OqHZTuyhf+5SNAwMhww2gUuy9twe03k1YFhSBGPtWDQ6btJYNi10+H+YXOZFnqJ0D rCOh967hyGgRNSD2QzalE2nA68bg1LD2It++UVehX4dK+mCok8cmsXIUF5/Xd+pMQ8 Rx9e2/pK++NflZJBAAKY0mw6EIVI+/52go75Et98186TyholvXwf49xHjnhKnUpfDr KBW99GpC5TUxG8RJR9H/Ns2DyL11WdcNqbWgMPZlA57KJD/FVBasw8e1kC81M570Xh 7pCSxgwfXPjHEZEi5ErKBxzLsduqFN7/SJpQPeOjQM+8eT0yfIfFM3OafMBsiT0cMw NrW2y0DVvo3yw== Received: by mail-lf1-f54.google.com with SMTP id f34so24861129lfv.10 for ; Tue, 31 Jan 2023 08:03:45 -0800 (PST) X-Gm-Message-State: AO0yUKXMbXGK2K1gHsgZ9IvlbyUinVJE/Xvzuxm5gp8fKGczIDguvCJ1 b8CensSms9OpQRtD3D/rWjNIjeMLBwRgOvl4gXU= X-Google-Smtp-Source: AK7set9S5k7gtqRiiMlvlOsZKuor0mBWUgdkw9E7GdqWo81k7IJisxGOI7efBe4gqidKZqYzpQunKAfGu/1g1jUSdx4= X-Received: by 2002:a19:c219:0:b0:4d7:2dc1:b7bc with SMTP id l25-20020a19c219000000b004d72dc1b7bcmr3332353lfc.100.1675181023886; Tue, 31 Jan 2023 08:03:43 -0800 (PST) MIME-Version: 1.0 References: <20221227092634.445212-1-liushixin2@huawei.com> <20230129134147.f19ca0641f1133f3e3bc185b@linux-foundation.org> <20230131150644.GA2605@willie-the-truck> <20230131150750.GB2605@willie-the-truck> In-Reply-To: <20230131150750.GB2605@willie-the-truck> From: Ard Biesheuvel Date: Tue, 31 Jan 2023 17:03:32 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH RFC] arm64/vmalloc: use module region only for module_alloc() if CONFIG_RANDOMIZE_BASE is set To: Will Deacon Cc: Andrew Morton , Liu Shixin , Catalin Marinas , Uladzislau Rezki , Christoph Hellwig , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 31 Jan 2023 at 16:07, Will Deacon wrote: > > Now really adding Ard... > > On Tue, Jan 31, 2023 at 03:06:44PM +0000, Will Deacon wrote: > > +Ard -- full thread here: > > > > https://lore.kernel.org/all/20221227092634.445212-1-liushixin2@huawei.com/ > > > > On Sun, Jan 29, 2023 at 01:41:47PM -0800, Andrew Morton wrote: > > > On Sun, 29 Jan 2023 10:44:31 +0800 Liu Shixin wrote: > > > > > > > Hi, > > > > > > > > > > > > This patch seems to have been lost in the corner. Recently I've meet this problem again > > > > > > > > on v6.1, so I would like to propose this patch again. > > > > > > > > > > > > Thanks, > > > > > > > > > > > > On 2022/12/27 17:26, Liu Shixin wrote: > > > > > After I add a 10GB pmem device, I got the following error message when > > > > > insert module: > > > > > > > > > > insmod: vmalloc error: size 16384, vm_struct allocation failed, > > > > > mode:0xcc0(GFP_KERNEL), nodemask=(null),cpuset=/,mems_allowed=0 > > > > > > > > > > If CONFIG_RANDOMIZE_BASE is set, the module region can be located in the > > > > > vmalloc region entirely. Although module_alloc() can fall back to a 2GB > > > > > window if ARM64_MODULE_PLTS is set, the module region is still easily > > > > > exhausted because the module region is located at bottom of vmalloc region > > > > > and the vmalloc region is allocated from bottom to top. > > > > > > > > > > Skip module region if not calling from module_alloc(). > > > > > > > > > > > I'll assume this is for the arm tree. > > > > > > Acked-by: Andrew Morton > > > > This looks like the same issue previously reported at: > > > > https://lore.kernel.org/all/e6a804de-a5f7-c551-ffba-e09d04e438fc@hisilicon.com/ > > > > where Ard had a few suggestions but, afaict, they didn't help. > > Thanks for the cc. So this is a bit clunky, and I wonder whether we wouldn't be better off just splitting the vmalloc region into two separate regions: one for the kernel and modules, and one for everything else. That way, we lose one bit of entropy in the randomized placement, but the default 48-bit VA space is vast anway, and even on 39-bit VA configs (such as Android), I seriously doubt that we come anywhere close to exhausting the vmalloc space today.