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=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 81D8FC49EA2 for ; Wed, 16 Jun 2021 06:23:14 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 16C4D61369 for ; Wed, 16 Jun 2021 06:23:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 16C4D61369 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 681316B006C; Wed, 16 Jun 2021 02:23:13 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6324F6B006E; Wed, 16 Jun 2021 02:23:13 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4D1776B0070; Wed, 16 Jun 2021 02:23:13 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0252.hostedemail.com [216.40.44.252]) by kanga.kvack.org (Postfix) with ESMTP id 17D636B006C for ; Wed, 16 Jun 2021 02:23:13 -0400 (EDT) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 8F885181AC9BF for ; Wed, 16 Jun 2021 06:23:12 +0000 (UTC) X-FDA: 78258594624.06.40F9790 Received: from mail-wr1-f46.google.com (mail-wr1-f46.google.com [209.85.221.46]) by imf01.hostedemail.com (Postfix) with ESMTP id 0DB765001533 for ; Wed, 16 Jun 2021 06:23:01 +0000 (UTC) Received: by mail-wr1-f46.google.com with SMTP id a11so1206920wrt.13 for ; Tue, 15 Jun 2021 23:23:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=+AuOceqtONtxu+lo6vPU+5Kb5RjCAa2n8NZkupuOuCk=; b=lv2hPI1YxVVIJ19l6aFGwWCsKPeGGpOJCROp1lzeRwrly5ZAo7y9Uic8RZoe3a6FCb JzQye16mK2VdF9xfJJKuWg+RM5gwW9TeiWA6BvkIbLV7WFBwQrpgU2A5J173OCi9a9G6 7ufNzI6ey9DCRdOV12Krl1VlYfuMPXapDPQSOiaiM4QNpby4hLt5259vUozOEEAQdHBk rXfiuWzn5wYmf5lnh8l0cy5eZ2I2z5+oEaXxfktd/stPhh9NPURMJrSbvPQi5T0Z1fEf gTQj3Mgj/MtkZ6jVBKGd9x0oRmgfqz3ybgjYHROTi6NOakb8W6av7S2rVFZTp/+Q2JFi Qr2w== 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=+AuOceqtONtxu+lo6vPU+5Kb5RjCAa2n8NZkupuOuCk=; b=EgT0Z8KhioGw28mcGEN/rAVxvY2kc3B1mGlcBWiqact5q7N/bC8dEUx3XBns3KEiS6 X0USSMao27UwTgZk1buCE1X8sWTlKI5LPxZxqw1RLfgqfPcwMv+uTUYmkfX9GB+9e2ie 6r4FByz8HZDZbOu5DP6fUdgBAtqiXO9iZgEHXSUtqB6BenOQmIS68ILgFLReDp9+i6CK T93Ij/Rohjozdcaf6XYloNUGAIL/mDpNoz+u+W41jUhpG2wMEf7KCoYVFQonqAi8YjlY wz/6tod3hkIdsdj88AFuOd2X+tqbtUGex2G61a5/aJHVl++jK/LWvcLvbQsKRs2Clznv UDYA== X-Gm-Message-State: AOAM533F6PvioTqAU5GFomMblip6DYlAXefM0zaO8pP4BvWl91ubV91o 7gqhx9RJ3w/CW6lAdW2LTYzJS7PUjdCXPBfdpxHgkQ== X-Google-Smtp-Source: ABdhPJz0TDJYcGni20w85SveWaxwrjq51VUWG2UorRuENeFDkPiOEDKTmbacr+mZM1h7/SToQxe+U8AG70BOrN2LGyg= X-Received: by 2002:a05:6000:1842:: with SMTP id c2mr3177980wri.426.1623824590788; Tue, 15 Jun 2021 23:23:10 -0700 (PDT) MIME-Version: 1.0 References: <20210612000714.775825-1-willy@infradead.org> In-Reply-To: From: Yu Zhao Date: Wed, 16 Jun 2021 00:22:59 -0600 Message-ID: Subject: Re: [PATCH] mm: Mark idle page tracking as BROKEN To: David Hildenbrand Cc: akpm@linuxfoundation.org, Linux-MM , Heiko Carstens , Rafael Aquini , Vlastimil Babka , Vladimir Davydov , "Kirill A . Shutemov" , Andrea Arcangeli , Donald Dutile , Matthew Wilcox Content-Type: text/plain; charset="UTF-8" Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=google.com header.s=20161025 header.b=lv2hPI1Y; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf01.hostedemail.com: domain of yuzhao@google.com designates 209.85.221.46 as permitted sender) smtp.mailfrom=yuzhao@google.com X-Rspamd-Server: rspam02 X-Stat-Signature: xwxg9ki4uin5gc1g5woax9cc9x3ia95i X-Rspamd-Queue-Id: 0DB765001533 X-HE-Tag: 1623824581-922006 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 15, 2021 at 8:55 PM Matthew Wilcox wrote: > > On Tue, Jun 15, 2021 at 09:41:37AM +0200, David Hildenbrand wrote: > > On 12.06.21 02:07, Matthew Wilcox (Oracle) wrote: > > > > I might be missing something important, so some questions/comments > > > > > In discussion with other MM developers around how idle page tracking > > > should be fixed for transparent huge pages, several expressed the opinion > > > that it should be removed as it is inefficient at accomplishing the > > > job that it is supposed to, and we have better mechanisms (eg uffd) for > > > accomplishing the same goals these days. > > > > 1. A link to that discussion would be nice. I am missing some important > > details in this patch description. > > It was on the phone in our bi-weekly THP call. As I recall, those > present were Kirill, Yu Zhao, William Kucharski, Zi Yan, Vlastimil Babka. > Song Liu sent apologies, and I think Mike Kravetz had a conflict. > > > 2. "should be fixed for transparent huge pages" -- has it always been like > > this or has the behavior changed at some point? Do the semantics, and how > > the feature is getting used, clearly identify this case that needs fixing as > > something that really has to be fixed? Or was it always like that and > > actually expected to work like that ("semtantics")? > > I don't know. I asked the others on the call and the answer I got was > essentially "Just delete it". > > I'm kind of hoping the others speak up. I listed a couple of things when acking this patch. Being broken is not a problem as long as there are users who care about it. What made me think such users may not exist is that nobody ever complained about those things until we stumbled on them -- I'm not insisting on deleting this feature, just clarifying why I thought so. The real question is how well we want to support it. My understanding, based on the previous discussion, is "as-is". That is we simply follow the current "semantics" when converting it to using folios.