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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 0BA9CC433DB for ; Thu, 11 Mar 2021 21:35:34 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7899B64F8E for ; Thu, 11 Mar 2021 21:35:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7899B64F8E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id EA3F78D02F8; Thu, 11 Mar 2021 16:35:32 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E40818D02B2; Thu, 11 Mar 2021 16:35:32 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CBA288D02F8; Thu, 11 Mar 2021 16:35:32 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0003.hostedemail.com [216.40.44.3]) by kanga.kvack.org (Postfix) with ESMTP id AAE458D02B2 for ; Thu, 11 Mar 2021 16:35:32 -0500 (EST) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 63C223499 for ; Thu, 11 Mar 2021 21:35:32 +0000 (UTC) X-FDA: 77908900104.04.26F5082 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by imf23.hostedemail.com (Postfix) with ESMTP id 395E3A0009CE for ; Thu, 11 Mar 2021 21:35:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1615498531; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=kZ6/mK85cx7Sa6K7XrwRqawHQQmlbukhYdWanrKMyJE=; b=PqMzBwpmIh72EiLCFM2lKgc9OFZ/C+94GtLzITMZwuX7MSTFXgwDaRQzXt2dwYKq7i+jK1 HQKDT850EoBoK3w+qTdSs2FkriqQCnpNYkX7kG/65rdEMFGKp94g7+P5SdF2J+yvx7Xus0 wsMA0JJ3FmOv+niEKqtk/msbGGB6s+M= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-413-ZrEpvKP8MsCpp6oSfbCyvg-1; Thu, 11 Mar 2021 16:35:27 -0500 X-MC-Unique: ZrEpvKP8MsCpp6oSfbCyvg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3F244363A8; Thu, 11 Mar 2021 21:35:26 +0000 (UTC) Received: from [10.36.115.26] (ovpn-115-26.ams2.redhat.com [10.36.115.26]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0422D5D742; Thu, 11 Mar 2021 21:35:20 +0000 (UTC) To: Peter Xu Cc: Linux Memory Management List , Minchan Kim , Matthew Wilcox , Rik van Riel , Michal Hocko , Andrea Arcangeli References: <20210311212628.GK194839@xz-x1> From: David Hildenbrand Organization: Red Hat GmbH Subject: Re: Page zapping and page table reclaim Message-ID: <634820ea-33bf-7423-cdea-ab3e63aa9729@redhat.com> Date: Thu, 11 Mar 2021 22:35:19 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <20210311212628.GK194839@xz-x1> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US X-Stat-Signature: 8bi7hpebzpxukk7tjjzc11wngc75gkii X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 395E3A0009CE Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf23; identity=mailfrom; envelope-from=""; helo=us-smtp-delivery-124.mimecast.com; client-ip=216.205.24.124 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1615498531-799669 Content-Transfer-Encoding: quoted-printable 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 11.03.21 22:26, Peter Xu wrote: > On Thu, Mar 11, 2021 at 07:14:02PM +0100, David Hildenbrand wrote: >> I was wondering, is there any mechanism that reclaims basically empty = page >> tables in a running process? >=20 > Would munmap() count? :) Haha, no -- also not mmap(FIXED) or mremap(FIXED) ;) As so often lately, the use case is sparse memory mappings where we a) may want to reuse the area later. b) don't want to hold the mmap lock in write while optimizing c) don't want to create a lot of individual mappings that we might not=20 be able to merge again. --=20 Thanks, David / dhildenb