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 56556ECAAA3 for ; Fri, 26 Aug 2022 21:06:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231700AbiHZVG2 (ORCPT ); Fri, 26 Aug 2022 17:06:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47304 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229676AbiHZVG0 (ORCPT ); Fri, 26 Aug 2022 17:06:26 -0400 Received: from mail-ej1-x632.google.com (mail-ej1-x632.google.com [IPv6:2a00:1450:4864:20::632]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5ECECDD76C for ; Fri, 26 Aug 2022 14:06:25 -0700 (PDT) Received: by mail-ej1-x632.google.com with SMTP id kk26so5301640ejc.11 for ; Fri, 26 Aug 2022 14:06:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc; bh=5PwylQXedxDhkWafpzB4KIy3NiEnlvim/yfJsbpjDbQ=; b=Yf9PjWlfL1r7eT/c/0AIKUjx+BKquW/wJnHvOD5xraOs6Zq6+qgnX0MvaVZZirGA29 MiCEjgTCWVH6qERy3ErADS+pQlFu0JZM6MMkgMyDzjmYTl7pzcjuduPfCeYXe62wir+R F/0AJRGshM9LobezTNYiztGwD4ALx554BVYmphaKX7b/HqjkDb7yE0CapdGKprLHC+uD NVhp5BNbj7GtIsj4wHzXNKBXu/nBCo5/+AtMQFMoQTJGxpubM3Nl1C2nlDuiKCFTD0OA rUPDJDe2Jk6Y9NkE7s0OgIZFirU9LpSK8tGo9v+OA4I+pXOc2aqEI54hnwrbByRa3Csa 4lMg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc; bh=5PwylQXedxDhkWafpzB4KIy3NiEnlvim/yfJsbpjDbQ=; b=lJ5DhZBEYsiKdSW+girlhObvHlt7w1LW7lwQjOk88ndq70VvRjNAh8vxZHJFIIRxZx MG9ltD9htmsCW09suOtReseq7AezSe4luhlMACLfRuYoJC/gpnupCn/w0xPHJfKJNuOQ RfxxOfALnbe8tsmfuKPZl5akN6oTIs/EjNo/j4sN+F6gpOwIZBZckHzFwEyUfxTHK2C5 GZvvRjGHjP8tDEIEbKaRSODaHfu9ZULBwlb+RBT5zequkMo65mhzCAdR3qXP0GJnFd5S sJMf8t7xygB6Os6k7NDT76PqiK0GywQv1JdL2PAiJbncbp4MT6ukoLAXJR4kFlyWKvOz N++Q== X-Gm-Message-State: ACgBeo0RVJl8rzoFAotCkWN+AfL77amS95AbZ5Cts48YCdQdRAhLBcLc ngXe7lkAdiEHf7XPqTTkMVFlSp0TukXImTtydmzD9tqA5Q== X-Google-Smtp-Source: AA6agR6Ncxwh8sZisapap17QKB0vCPLvZPFGD64SjhSRwQj5pNJD2743vRLKzk92RbbdMrcFnobg9pLitg0Rbm61fT0= X-Received: by 2002:a17:907:6096:b0:73d:9d12:4b04 with SMTP id ht22-20020a170907609600b0073d9d124b04mr6717363ejc.745.1661547983987; Fri, 26 Aug 2022 14:06:23 -0700 (PDT) MIME-Version: 1.0 References: <1661502678-19336-3-git-send-email-kaixuxia@tencent.com> <20220826171629.50210-1-sj@kernel.org> In-Reply-To: <20220826171629.50210-1-sj@kernel.org> From: Kaixu Xia Date: Sat, 27 Aug 2022 05:06:12 +0800 Message-ID: Subject: Re: [PATCH 2/2] mm/damon/vaddr: remove comparison between mm and last_mm when checking region accesses To: SeongJae Park Cc: akpm@linux-foundation.org, damon@lists.linux.dev, linux-mm@kvack.org, LKML , Kaixu Xia Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Aug 27, 2022 at 1:16 AM SeongJae Park wrote: > > Hi Kaixu, > > On Fri, 26 Aug 2022 16:31:18 +0800 xiakaixu1987@gmail.com wrote: > > > From: Kaixu Xia > > > > The damon regions that belong to the same damon target have the same > > 'struct mm_struct *mm', so it's unnecessary to compare the mm and last_mm > > objects among the damon regions in one damon target when checking accesses. > > There could be multiple targets, and 'damon_va_check_accesses()' calls > '__damon_va_check_accesses()' for all the targets. However, > 'damon_va_check_accesses()' doesn't note if '__damon_va_check_accesses()' is > called with a target that same to the target it was called with for the last > time. Hence the check is necessary. There could be many regions(1000 max limit) in one target and the mm is same within the target, maybe we don't need to maintain the 'last_mm' and do the check every time when the target is same. But yes, the check is necessary when the target changed in '__damon_va_check_accesses()', this RFC patch missed this case :) will fix it. > > If I'm missing something, please let me know. > > > Thanks, > SJ > > [...]