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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 02C84C433FE for ; Fri, 15 Apr 2022 01:15:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239926AbiDOBSB (ORCPT ); Thu, 14 Apr 2022 21:18:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34402 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231893AbiDOBR6 (ORCPT ); Thu, 14 Apr 2022 21:17:58 -0400 Received: from mail-vk1-xa2a.google.com (mail-vk1-xa2a.google.com [IPv6:2607:f8b0:4864:20::a2a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 24F7B7CDD2 for ; Thu, 14 Apr 2022 18:15:32 -0700 (PDT) Received: by mail-vk1-xa2a.google.com with SMTP id r130so1758321vkr.10 for ; Thu, 14 Apr 2022 18:15:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=sqQ5iSXHRChMtfKt3RIiTUV6la+/DUpLnLLVZuKBh7Q=; b=oviqlwgsbsf/uMOiFPTaRFR184BPOabtCsqvs6xHtrlZpVbO4wKVB0eo7OE3eF6N/f WoaWM5yeZZLbX4bTnkrRStEi99QdeKS6Z3yPjXlEJ8thMjBN2y6vtiXz9+r5waIlarMi PEuJDrqRxDNGWEvZtqcjJ6wDZjHCrtXjyW8RCewvZZTM8b8ewk2aMLxst08o3jkmgvHj dBaMIEPKx2pirgP/PA/oNB8wvUGcKYkBWFZi8QlKZ5MZdK/U1NzAv8EWY+L7ieWQPXio KQeZRRy2WP6HjteGasYoS9ndZF9Muc0bdCZWEfz9K4vzCapbUgbZygSvSEc1A6iW2EBz SL8w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=sqQ5iSXHRChMtfKt3RIiTUV6la+/DUpLnLLVZuKBh7Q=; b=4omK45oFptnD9PnunLjFVjeCrF99ZqKX6btY80EaS2Dtx10Lm4Qeh3IiaYtmel4gQ0 BaDkdlLPeIsArkJ972HpLQwDU6iAJMabsJNesIfSNe0N1lKlpAO/kt0YNZ2W9YHxH7Li GCy+hL8QAQWjZ/f4EIzQvx4PHhME++gHeYn7Gxl6en+Owd41sFAkiPo582q5pUCd+DvF AMjPvJHorrn1UIBMWSOtsFwrgWjQibigsGGSLisXW0fl7EtBsR+KgvcNJgszKEzAIHpC WKTxLOQjFp1dcO8o9Dv8CE5DAGy/iN7iXRwU76uE5UnpKnuqHQixMDOPC3avX2Wsz93p kW7Q== X-Gm-Message-State: AOAM5306zh7EmptQh4XohnzdhfzG8teNBted4Y7Mc1FYuV/Sn+WeZmoU gJ+VWekmVTWNzctpykljErHNka+AjrFkZm8M3iMX+Q== X-Google-Smtp-Source: ABdhPJwvGDjSCKwPleIWn79rkQzoHHhv5ROws7qejBtcO8EAQjqcBUMU+Hjaa8vtashbeHOejWBcqwTJDS8z7VZov/8= X-Received: by 2002:a1f:314b:0:b0:331:fff6:a89e with SMTP id x72-20020a1f314b000000b00331fff6a89emr2454874vkx.26.1649985331160; Thu, 14 Apr 2022 18:15:31 -0700 (PDT) MIME-Version: 1.0 References: <20220407031525.2368067-1-yuzhao@google.com> <20220407031525.2368067-9-yuzhao@google.com> <20220411191621.0378467ad99ebc822d5ad005@linux-foundation.org> In-Reply-To: <20220411191621.0378467ad99ebc822d5ad005@linux-foundation.org> From: Yu Zhao Date: Thu, 14 Apr 2022 19:14:54 -0600 Message-ID: Subject: Re: [PATCH v10 08/14] mm: multi-gen LRU: support page table walks To: Andrew Morton Cc: Stephen Rothwell , Linux-MM , Andi Kleen , Aneesh Kumar , Barry Song <21cnbao@gmail.com>, Catalin Marinas , Dave Hansen , Hillf Danton , Jens Axboe , Jesse Barnes , Johannes Weiner , Jonathan Corbet , Linus Torvalds , Matthew Wilcox , Mel Gorman , Michael Larabel , Michal Hocko , Mike Rapoport , Rik van Riel , Vlastimil Babka , Will Deacon , Ying Huang , Linux ARM , "open list:DOCUMENTATION" , linux-kernel , Kernel Page Reclaim v2 , "the arch/x86 maintainers" , Brian Geffon , Jan Alexander Steffens , Oleksandr Natalenko , Steven Barrett , Suleiman Souhlal , Daniel Byrne , Donald Carr , =?UTF-8?Q?Holger_Hoffst=C3=A4tte?= , Konstantin Kharlamov , Shuang Zhai , Sofia Trinh , Vaibhav Jain Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 11, 2022 at 8:16 PM Andrew Morton wrote: > > On Wed, 6 Apr 2022 21:15:20 -0600 Yu Zhao wrote: > > > +static void update_batch_size(struct lru_gen_mm_walk *walk, struct folio *folio, > > + int old_gen, int new_gen) > > +{ > > + int type = folio_is_file_lru(folio); > > + int zone = folio_zonenum(folio); > > + int delta = folio_nr_pages(folio); > > + > > + VM_BUG_ON(old_gen >= MAX_NR_GENS); > > + VM_BUG_ON(new_gen >= MAX_NR_GENS); > > General rule: don't add new BUG_ONs, because they crash the kenrel. > It's better to use WARN_ON or WARN_ON_ONCE then try to figure out a way > to keep the kernel limping along. At least so the poor user can gather logs. These are VM_BUG_ONs, which are BUILD_BUG_ONs except for (mostly MM) developers. 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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=sqQ5iSXHRChMtfKt3RIiTUV6la+/DUpLnLLVZuKBh7Q=; b=PInD8w8wFDe5+9ImlDMir+CO42r8P6IDDnQ7TRFVANLmI95cbUk7e5daBkt/GtUfyH 509bQa7HjdLnLM/coSeo3HOV95GU2ohrsrWqhghCm96X1G5nre7gRjKK2GDMf8Od7pI3 DjeRNzh6CJmm/j0A8ASdGTLFplIuPMBTceUnG9Y5Xvj/G5O62jVrr7p+Mgk4bLxxGIPJ kKvbh43DKh2ZR483XpPe+du4d8uVtuViY6y1TueOwyHhvbcwX+2zUo7zqF971JgTNgRX Fk2EjBf/aBOLRkhnkMePXBEHcdG219439PVsSzoBwqNjy0rEss+CHfqC2HXy5qNWuutN rnig== X-Gm-Message-State: AOAM533naotpZ3Grk3XrqDERLwgLzhUSBqV1HKT++O/34NBPXOX5LylN PvU9Uma1PBYghF4QqY0x2QQCcq6K8T9QnRInKMKwYw== X-Google-Smtp-Source: ABdhPJwvGDjSCKwPleIWn79rkQzoHHhv5ROws7qejBtcO8EAQjqcBUMU+Hjaa8vtashbeHOejWBcqwTJDS8z7VZov/8= X-Received: by 2002:a1f:314b:0:b0:331:fff6:a89e with SMTP id x72-20020a1f314b000000b00331fff6a89emr2454874vkx.26.1649985331160; Thu, 14 Apr 2022 18:15:31 -0700 (PDT) MIME-Version: 1.0 References: <20220407031525.2368067-1-yuzhao@google.com> <20220407031525.2368067-9-yuzhao@google.com> <20220411191621.0378467ad99ebc822d5ad005@linux-foundation.org> In-Reply-To: <20220411191621.0378467ad99ebc822d5ad005@linux-foundation.org> From: Yu Zhao Date: Thu, 14 Apr 2022 19:14:54 -0600 Message-ID: Subject: Re: [PATCH v10 08/14] mm: multi-gen LRU: support page table walks To: Andrew Morton Cc: Stephen Rothwell , Linux-MM , Andi Kleen , Aneesh Kumar , Barry Song <21cnbao@gmail.com>, Catalin Marinas , Dave Hansen , Hillf Danton , Jens Axboe , Jesse Barnes , Johannes Weiner , Jonathan Corbet , Linus Torvalds , Matthew Wilcox , Mel Gorman , Michael Larabel , Michal Hocko , Mike Rapoport , Rik van Riel , Vlastimil Babka , Will Deacon , Ying Huang , Linux ARM , "open list:DOCUMENTATION" , linux-kernel , Kernel Page Reclaim v2 , "the arch/x86 maintainers" , Brian Geffon , Jan Alexander Steffens , Oleksandr Natalenko , Steven Barrett , Suleiman Souhlal , Daniel Byrne , Donald Carr , =?UTF-8?Q?Holger_Hoffst=C3=A4tte?= , Konstantin Kharlamov , Shuang Zhai , Sofia Trinh , Vaibhav Jain X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220414_181532_785281_047302CA X-CRM114-Status: GOOD ( 13.54 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Apr 11, 2022 at 8:16 PM Andrew Morton wrote: > > On Wed, 6 Apr 2022 21:15:20 -0600 Yu Zhao wrote: > > > +static void update_batch_size(struct lru_gen_mm_walk *walk, struct folio *folio, > > + int old_gen, int new_gen) > > +{ > > + int type = folio_is_file_lru(folio); > > + int zone = folio_zonenum(folio); > > + int delta = folio_nr_pages(folio); > > + > > + VM_BUG_ON(old_gen >= MAX_NR_GENS); > > + VM_BUG_ON(new_gen >= MAX_NR_GENS); > > General rule: don't add new BUG_ONs, because they crash the kenrel. > It's better to use WARN_ON or WARN_ON_ONCE then try to figure out a way > to keep the kernel limping along. At least so the poor user can gather logs. These are VM_BUG_ONs, which are BUILD_BUG_ONs except for (mostly MM) developers. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel