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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 17DE5C10DCE for ; Tue, 24 Mar 2020 03:50:40 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C72852073E for ; Tue, 24 Mar 2020 03:50:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="i0LcT5mG" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C72852073E 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 4BAD36B00C3; Mon, 23 Mar 2020 23:50:39 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 46B666B00C5; Mon, 23 Mar 2020 23:50:39 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 381ED6B00C6; Mon, 23 Mar 2020 23:50:39 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0056.hostedemail.com [216.40.44.56]) by kanga.kvack.org (Postfix) with ESMTP id 217A16B00C3 for ; Mon, 23 Mar 2020 23:50:39 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 2FB331C951 for ; Tue, 24 Mar 2020 03:50:39 +0000 (UTC) X-FDA: 76628878998.17.death74_7a15fe877c757 X-HE-Tag: death74_7a15fe877c757 X-Filterd-Recvd-Size: 4343 Received: from mail-io1-f66.google.com (mail-io1-f66.google.com [209.85.166.66]) by imf30.hostedemail.com (Postfix) with ESMTP for ; Tue, 24 Mar 2020 03:50:38 +0000 (UTC) Received: by mail-io1-f66.google.com with SMTP id n21so16665476ioo.10 for ; Mon, 23 Mar 2020 20:50:38 -0700 (PDT) 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=0PWtGiTip51w7AvNDGxGNVzprTbrcKfQvRf4bXl7b0U=; b=i0LcT5mGofQj4T9zG9L8etGLT6EXEZ0ZiAamKXs6N8Eeb+xYV+soyJvKQePixcTtlT PtRuLXjn6OHHZUpOFjBNJxVimlvy+jveG4VRTCcyPP+imaz6L8uRpnAN4eN81om6A8p/ p7bx4EC7NgC/+6YCJ2kVx42VRYYdP/AQckF5A67qw+SX5M8/ZBWAVk5XIqKbF/tpSTHe bYtHoRzBSzaMYLlSvtvrGPBlHGeIW8AeBThA1PffHQTmrlmBDJPGb5knXRtbd4IVQ0Qo jjA0uWoarbv4NKlA45sxAmQxGmQEMWEolVsdmisQU/hELb1p4/tWXSfuYxEm7iR8QKpD NGCA== 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=0PWtGiTip51w7AvNDGxGNVzprTbrcKfQvRf4bXl7b0U=; b=fL5oJeviVxjzFxiaWcOAC9Q8xb9P4k5b9GbQ3Vpwjpp3MQFzDmRSBr3r++poKoBywD KWx7OWi8vgfhnnonUgbJdX5V62E5QB0pACR+3SE1PdWxHHqpMRf0jPtAPlHZLajS1seW dTgTk8uQgG11wqceLy5U6tvEbnpPaYkMOvRR+cyt1ka1p4fdJVh2zgyMl1aDfkFfneD+ gq688Yk8vzPvJHXgJO2b365lC3abKej91f3vDCoqgF2tgPn66B+fg+TX4GXqBkzqh9ph uVLzOPv3XE0gLUiIARr1TFR4uGZqNY9VeiNntJPCUgKR8QnrHoF62T3iSUAfcpRLOr+c /ikA== X-Gm-Message-State: ANhLgQ2Au1OkTu8sO12eDYqL8HC0FCKUEPwQL3XM+amPRcIw8oN5UTdI KrQxj4Xy4tGytoYP/dVspKBtOtKTFd5fjVUSdwKw X-Google-Smtp-Source: ADFU+vstBpvX93waNFkH+DsIH2Bq0jzRFHDlG9hK4WrRu5kwIuU8HFXHVOUhFAUA2UwfEXT7itx0bKpnfT/BvhrMez4= X-Received: by 2002:a6b:bd04:: with SMTP id n4mr22099288iof.196.1585021837970; Mon, 23 Mar 2020 20:50:37 -0700 (PDT) MIME-Version: 1.0 References: <1584885427-4952-1-git-send-email-kernelfans@gmail.com> <20200323073408.GA7524@dhcp22.suse.cz> In-Reply-To: From: Pingfan Liu Date: Tue, 24 Mar 2020 11:50:26 +0800 Message-ID: Subject: Re: [PATCH] mm/rmap: fix the handling of device private page in try_to_unmap_one() To: John Hubbard Cc: Michal Hocko , Linux-MM , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , "Kirill A . Shutemov" , Aneesh Kumar , Andrew Morton , Dan Williams , Ralph Campbell 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, Mar 24, 2020 at 7:32 AM John Hubbard wrote: > > On 3/23/20 12:34 AM, Michal Hocko wrote: > > On Sun 22-03-20 21:57:07, Pingfan Liu wrote: > >> For zone_device, migration can only happen on is_device_private_page(page). > >> Correct the logic in try_to_unmap_one(). > > > > Maybe it is just me lacking knowledge in the zone_device ZOO. But > > this really deserves a much more detailed explanation IMHO. It seems > > a5430dda8a3a ("mm/migrate: support un-addressable ZONE_DEVICE page in > > migration") deliberately made the decision to allow unmapping these > > pages? Is the check just wrong, inncomplete? Why? > > > > What is the real user visible problem here? > > > > I was going to guess that someone was having trouble with the behavior on > non-device-private ZONE_DEVICE pages, but...I am also at a loss as to > what triggered this patch. So, I have the exact same questions as Michal, > plus really wondering what tests you are running, and on what hardware config. :), please see my reply to Michal. > > It's hard to get the right CC's, but probably Dan Williams and Ralph Campbell > should also be added, if you are sure you need this. (I'm adding them now.) Appreciate you to do that. In fact, I am not sure about some detail, and hope someone can correct me if I make mistake. Thanks, Pingfan