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=-2.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 96C8DC433DB for ; Tue, 26 Jan 2021 14:37:58 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 227AA22D58 for ; Tue, 26 Jan 2021 14:37:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 227AA22D58 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 21E058D00D2; Tue, 26 Jan 2021 09:37:57 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1CFF78D00B0; Tue, 26 Jan 2021 09:37:57 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0E5A68D00D2; Tue, 26 Jan 2021 09:37:57 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0050.hostedemail.com [216.40.44.50]) by kanga.kvack.org (Postfix) with ESMTP id ECD1D8D00B0 for ; Tue, 26 Jan 2021 09:37:56 -0500 (EST) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id ADEDE180AD804 for ; Tue, 26 Jan 2021 14:37:56 +0000 (UTC) X-FDA: 77748180552.25.space75_1f047a42758f Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin25.hostedemail.com (Postfix) with ESMTP id 7D7551804E3A1 for ; Tue, 26 Jan 2021 14:37:56 +0000 (UTC) X-HE-Tag: space75_1f047a42758f X-Filterd-Recvd-Size: 3663 Received: from mail-lj1-f172.google.com (mail-lj1-f172.google.com [209.85.208.172]) by imf32.hostedemail.com (Postfix) with ESMTP for ; Tue, 26 Jan 2021 14:37:56 +0000 (UTC) Received: by mail-lj1-f172.google.com with SMTP id r14so1107529ljc.2 for ; Tue, 26 Jan 2021 06:37:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=aQ0sGbOXo3r95TI0acGYL4FiPHxiJFhrAwTcJFN50dg=; b=Di5SPVED58vG22M8kGFzOl4LSoEU6890g3Ev9UWQolk4VhCATP1l3yCYCogdEtZm9J ks8A7da/DEiVOpL5kIssh08CCYRJfdnHyg7xmM1VCOI9je3MiF0KbJBlfc+2qsClDu8u 3MAz+6U4t+rmw+N+dejVm0SHEoA09450mNn2Tc/TEIR2y/Tc/xQ3mZLrZJdsx3ITBp9f RLQIFh5TGXqSkcEM1DqS+RyzAVt1uMBauihaUZ6PzimhfdAgxs4a0IMDbmIQkNkUHsum /jrkI8/C4gchyGPozwhn/1dR3QGS8Unoo0NGg4+5OUUkzjqjDG4v/MN8UlnfNYXbQcXf CQvw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=aQ0sGbOXo3r95TI0acGYL4FiPHxiJFhrAwTcJFN50dg=; b=J3Mcc9jpGqWEBQmxZjmpPHiPOxqe1GbiHEf8V993BaIbFauXJuZVEsWQ+ryxOK+FEu ibmkInTbLeheMjUKpKmrhrVXGmoIh3SSSMliOTM3tGAlsdPt5i7UGbeCmWf8aGPes0Hf sm91ewo4Ua5ZoMD2Rbhn54MWP25Oj/aru8Hb3JKc5QDioYThcju4W8cmzwrXeCta6oj8 Py/m6eHP6BLp6t2B7u2ScBd4Ad7wlaXkvWqyfUwUVT2Rr4EBgz7rWEO+xh8+HdlXW6VK uV2iT6NsEyKOX4rsdAFe9EIaQH5oY7k+ZFbaKMst6SMtnLxDAUEWETOaa4aLDYjwQm6x 5ZsQ== X-Gm-Message-State: AOAM533tjWXVkBs0N3A/H6WAra+0IRd87epjyPVZyI74/CN16YVvezZt OHSMDU4gEH3W4VL1gi9ZZQBrlYsqOBXd3LzF5t9Ojqb9DygSBXpZ X-Google-Smtp-Source: ABdhPJxCyYM525lnR6ilN5dnREMkk+if5yGItnNSDaDEtiWtq0O7qCQjqKGeiXM7iOqDIaV183Zb+2cQ0zli4lFp1vg= X-Received: by 2002:a2e:b1d4:: with SMTP id e20mr1516269lja.103.1611671874548; Tue, 26 Jan 2021 06:37:54 -0800 (PST) MIME-Version: 1.0 References: <20210123154320.24278-1-vvghjk1234@gmail.com> <0ed60e73-9c4f-5a62-754d-b3c864239941@suse.cz> In-Reply-To: <0ed60e73-9c4f-5a62-754d-b3c864239941@suse.cz> From: Wonhyuk Yang Date: Tue, 26 Jan 2021 23:37:45 +0900 Message-ID: Subject: Re: [PATCH] mm/compactoin: Fix edge case of fast_find_migrateblock() To: Vlastimil Babka Cc: Andrew Morton , Mel Gorman , linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" 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, Jan 26, 2021 at 1:49 AM Vlastimil Babka wrote: > > Maybe instead of replacing one magic value of 'pfn' with another > (cc->migrate_pfn with high_pfn) I would just add a "bool found" and use it > appropriately. Would make the function less subtle perhaps. I agree. Using that bool variable will look good. > > While reviewing I found more potentially questionable parts, if you're interested: > > - if we go through "if (get_pageblock_skip(freepage))... continue;" we are > increasing nr_scanned++; but not checking the limit. Yes, you've got a point. I think nr_scanned checking should be first. > > - the "if (list_is_last(freelist, &freepage->lru)) break;" part seems > unneccesary? if we are on the last page and just "continue;" the > list_for_each_entry() iteration should stop anyway. > Yes It seems unnecessary. only if the skipped block was reordered, it would be required. Then I will reflect your opinion and send a new version.