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Fri, 15 Apr 2022 01:15:32 +0000 (UTC) X-FDA: 79357345704.23.100F41F Received: from mail-vk1-f182.google.com (mail-vk1-f182.google.com [209.85.221.182]) by imf18.hostedemail.com (Postfix) with ESMTP id 166D71C0002 for ; Fri, 15 Apr 2022 01:15:31 +0000 (UTC) Received: by mail-vk1-f182.google.com with SMTP id r130so1758323vkr.10 for ; Thu, 14 Apr 2022 18:15:31 -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=AO0kudhvkCY2upaV4lngeFWyM4T2Gal8nkH/rohQLS9VKuizCisUo/T1L8A7GI4+w6 qayKE1tbhe6UpbPio7rkS2M+zFYCalgDijkBi9AJEOB0+khEw0IMyiaWheddaQd4Vbwe S933fwBLbhnaujlpoAmrzA70NiDi83PKsol44E9KcfacYaOM/nNfAqA6cm426sETq+q4 VS1dj3ebDCj7tE8HX0+I2qlLxxmW4tJkHH+3iFo2+iGdMCfrl/31E2gassGFZZidzDrE DUgpvQnTpdDAbQS+QobLiDRSVY4jKZNS7lVcpAcB0eSOsvv1DN1REVG1X0bxm+APWutF y7xA== X-Gm-Message-State: AOAM532p+Nb18xaRhKa8+Z/oSpkPfvZjqraqVTrBsU7FuHZ2tqrexWO9 xQ7sqcRj2cYTgUia+YDI+GVgPUx8UpjKCuqTwEy/QQ== 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" X-Stat-Signature: 6aziacojykfrwh3q1cy1z93gpqogy15s X-Rspam-User: Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=oviqlwgs; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf18.hostedemail.com: domain of yuzhao@google.com designates 209.85.221.182 as permitted sender) smtp.mailfrom=yuzhao@google.com X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 166D71C0002 X-HE-Tag: 1649985331-761272 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 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.