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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 23C63C43334 for ; Tue, 7 Jun 2022 10:23:15 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9C0EA8D0002; Tue, 7 Jun 2022 06:23:14 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 96F756B007E; Tue, 7 Jun 2022 06:23:14 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 85F878D0002; Tue, 7 Jun 2022 06:23:14 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 7713E6B007D for ; Tue, 7 Jun 2022 06:23:14 -0400 (EDT) Received: from smtpin31.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay11.hostedemail.com (Postfix) with ESMTP id 548AB80C73 for ; Tue, 7 Jun 2022 10:23:14 +0000 (UTC) X-FDA: 79551052308.31.E0C0452 Received: from mout.kundenserver.de (mout.kundenserver.de [217.72.192.73]) by imf21.hostedemail.com (Postfix) with ESMTP id 65FE61C0065 for ; Tue, 7 Jun 2022 10:22:57 +0000 (UTC) Received: from mail-yb1-f178.google.com ([209.85.219.178]) by mrelayeu.kundenserver.de (mreue107 [213.165.67.113]) with ESMTPSA (Nemesis) id 1MrPRB-1nRua83sCF-00oYyU for ; Tue, 07 Jun 2022 12:23:12 +0200 Received: by mail-yb1-f178.google.com with SMTP id v22so30368231ybd.5 for ; Tue, 07 Jun 2022 03:23:11 -0700 (PDT) X-Gm-Message-State: AOAM531ZSk67wq7jZm32RlofmFcemCStsjuMZmcrJz8graeXXCftKpNp s+8BiB2ePsJZOsaejceMifExFk4NM1ptOt6CPAc= X-Google-Smtp-Source: ABdhPJyK/OKc2K9YITf8oi2lFf7oHpQ+paYy09hCFaenZ0wZAWsEzxAyQFesx12PiB1NuQCON1KK+PtT3YdlxGcRL1Q= X-Received: by 2002:a25:31c2:0:b0:641:660f:230f with SMTP id x185-20020a2531c2000000b00641660f230fmr28844707ybx.472.1654597390472; Tue, 07 Jun 2022 03:23:10 -0700 (PDT) MIME-Version: 1.0 References: <70b4e1e46d9d63275a0dfe90f96f40ea14d89f0c.camel@infinera.com> <88dfec5a1c98f4eb71e23cafe89db4395ea12811.camel@infinera.com> In-Reply-To: From: Arnd Bergmann Date: Tue, 7 Jun 2022 12:22:53 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: Finding kernel RAM consumers ? To: "Russell King (Oracle)" Cc: Arnd Bergmann , Matthew Wilcox , Joakim Tjernlund , "linux-mm@kvack.org" , Linux ARM Content-Type: text/plain; charset="UTF-8" X-Provags-ID: V03:K1:J+q2ph8zaZ/ysB1Y4WUtLOV/ybbugDlOcMr0JvuvpCPYcCW5M+8 9JsGtFI2wWIlsBlLlY011PK4H2ANVR/EJwr+3wkU13b6SldMmBSrRww1hrUhlH7BdITnAbc pie/Alee1n+j8XHGsExS3g+bBMkyQ+NBcaDTH65M1uMFXKTOUcwoolZBnIyw6xDrPWSBB39 xlp5QjWcn9JI3L9rfZszA== X-UI-Out-Filterresults: notjunk:1;V03:K0:/d/xrfNAHS8=:yESuqYHa/ufX/9wXM6I94e yOvDcgTgIyRufTsORZ4M8hrTeu9RatqwL6HDT/kSxH8myEitwuUjj+tp9JGr60hpiPrw4feAi fT1pjfG8EFgIr7EJ/8M6lGEBIDtg8abmFRDeIk2tD4T7USimf+UEsT9THXVpTLlNO/zk7/zB6 AJjgLRq/25fvZwJi4mWAYqj9+fFcdSkKuQITDdsGcQc75vF4cEAsmpIN1/OszpGil8/jkQ6Qg abuvAUl/Wa5rXz6H9+WnzVb4LhzS9+O9VQrSXtTl7DZGeXxpBhU/ybOk2uoyow8OXLphRVRDX LqLHf3z3iz+x1lgv0+WDnFNNg9QpXjyHuwnRAWrqVssvPrDh86TJzb6HPRX/Ei6CYcwi/9IhN uIApFg82pvQHh1NGY8O0Zs6THi1eMxeCWmafrzkO4bXrKzad220HZGQkDYcR4WIzzjmU3Ebx+ el8X8NUhbwuwv60fNJNuKsvmof+gJAakAoXw8mW6vzB0fr4Icl2qNoOhJOcDjVic8xVuIs8nQ dzL1J0MZRbjW+qYPJ0trL2nW5guhM75tUEZH7IUETItzSIIup18pymuV0XoqHdDejfzjaDAY0 3WXPcl2G36AyN1Dm+25oVIrRn78NZRxzLdMkTVPbgK7eBCRC6xBTTT1Ua37Xb2C5U77xJVsii lv4Eehz6eXFxePre3c5Wq5FLIk2aRXZ2yZnPqCW0SYk0BX7bOXLTa2yRixrA5iUxQNnCilMqQ 5kQZ8tpPFirLPFyTl7+PrEWw8bzrH4uHR2l9MV4vc8vYX2ETIzVW+I0b4m5kDTYgt7aHeC6np TpZF2glUpOvQqlXklti8e0yMOvRlAm4qoy8XztScMI7ULkICAn4Eh14g2iH0XsYn/Bvp8/R63 JKOzV0ldBCWTQOxbVP57qEuVm6/bqTLJw+Rt3yF3I= X-Stat-Signature: 7sbk91b86ywpibtyqr75muz9icw47eke X-Rspam-User: Authentication-Results: imf21.hostedemail.com; dkim=none; spf=none (imf21.hostedemail.com: domain of arnd@arndb.de has no SPF policy when checking 217.72.192.73) smtp.mailfrom=arnd@arndb.de; dmarc=none X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 65FE61C0065 X-HE-Tag: 1654597377-891183 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: On Tue, Jun 7, 2022 at 11:44 AM Russell King (Oracle) wrote: > On Tue, Jun 07, 2022 at 10:38:54AM +0200, Arnd Bergmann wrote: > > > > Yes, of course, and there is nothing wrong with that. We already see > > Cortex-A7 cores down to 7nm, all running Linux, and I expect there > > will likely be another 5 to 10 years of new 32-bit chips, and then another > > 10 years of people putting the existing chips into production, and after > > that a slow decline of users updating their kernels before supporting > > 32-bit hardware becomes too expensive to support in the kernel. > > It should be noted that 20 years puts us past the 2038 32-bit time_t > wrap problem - and although there's been work to address that in the > UAPI, that doesn't mean that userspace will cope. > > Anyone deploying a system that is expected to still be live beyond > the end of 32-bit time_t had better be testing their userspace for > that event now! That is absolutely true, but it's also independent of what kernel is being used. I assume that anyone who is this memory constrained is using 32-bit thumb userspace even on 64-bit kernels. The base distro support in embedded systems using openembedded with musl-1.2.x usually works fine beyond y2038, but of course each system should be tested for this before shipping as there are still bugs in less common code. arnd