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=-2.8 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 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 C464CC07E99 for ; Mon, 12 Jul 2021 10:18:05 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5226F60FDA for ; Mon, 12 Jul 2021 10:18:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5226F60FDA 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 69E976B008A; Mon, 12 Jul 2021 06:18:05 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 64E266B008C; Mon, 12 Jul 2021 06:18:05 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4EE926B0092; Mon, 12 Jul 2021 06:18:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0155.hostedemail.com [216.40.44.155]) by kanga.kvack.org (Postfix) with ESMTP id 2C1CA6B008A for ; Mon, 12 Jul 2021 06:18:05 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 25BE7230F9 for ; Mon, 12 Jul 2021 10:18:04 +0000 (UTC) X-FDA: 78353535288.14.87BCA80 Received: from mail-il1-f176.google.com (mail-il1-f176.google.com [209.85.166.176]) by imf07.hostedemail.com (Postfix) with ESMTP id CB64410036B2 for ; Mon, 12 Jul 2021 10:18:03 +0000 (UTC) Received: by mail-il1-f176.google.com with SMTP id b6so9311527iln.12 for ; Mon, 12 Jul 2021 03:18:03 -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=TCCESK6Bc1wwnfg5+EzFKimyzbdn7k622CCYhv007tQ=; b=mNyl0Rh5ytiAYrqLqGBa6bx66uG0GZb2TA/Pb8M3DNT/fOVQn6k0MzIIEwKFT+2YMU b6YYT4Vh+bbvJyN18e5ro3hdfDedq2cI6BiazPPTfcCnQLqp45krYGFYO8KDqYpICvXB rBn5dXvKCZ+SpVMfKZ5NV7TGb5tAGitDT84m0FYEuK1WjczCbrH1oxhjCD2nr6UWLCrS cU5bjr7dhW0qUDjetshh1ah0WCsZ6+CwgWpvucMz3+LqE4djhUT1Wee2wOzbpelI95yz GLLkSTBCSL/X/FikRAmf71ygp6oKx3omrTR2AM8h6BYwaYqsOBbfegr4SfXworU2hGc1 +GcQ== 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=TCCESK6Bc1wwnfg5+EzFKimyzbdn7k622CCYhv007tQ=; b=k33VFo0BHjfdb5HYmEr2mlU4EgMnXHVOpG4nAI6VTu9hP4HLWMPoHSHswrDteu/HXR NbbSpaLwDecJAWceVK+Ulk7zrAWHQPO20bSwCkNyz8XyQTizTg83Y2Q7iAYjlgxYlLf+ zWpycCP88N2r4s7HnLxw8l9a54KvX/w3jku/rXylgTkSqRp6vrv21OV+0uuwtW09HEUk LsxXw6zB9fuUMfGLpGdwwU14B9z98tl6Flr1ClJWs1GEcQ17LyvTyuhMYd7KarGmJ19o wI3UbHYbnOGsReudTdgK8xCmaJAPEqU8INH7Z4TtqBBPiej9IFiHfBchlMEFhqhxYWJq X6jA== X-Gm-Message-State: AOAM532k1KyJ3JKSLfPtLTEyKxlP+ml3tB3CM3Tw4D/ebaGPEYYw914V 4WE38cELJuXURHG9u6EG0cw2gugSZlAHeXWF3ts= X-Google-Smtp-Source: ABdhPJzkczPjG/Xa9gJdDwwffQX6ykoawYLibXHgJcYo2Kz1/4jR5f8beUvN5/WlvhmPQFv1N6OCb1vgXYbeeJH6StM= X-Received: by 2002:a05:6e02:1529:: with SMTP id i9mr2832886ilu.163.1626085083176; Mon, 12 Jul 2021 03:18:03 -0700 (PDT) MIME-Version: 1.0 References: <20210712083917.16361-1-david@redhat.com> <406695f0-13c8-a052-92d4-44e884eb44af@redhat.com> In-Reply-To: <406695f0-13c8-a052-92d4-44e884eb44af@redhat.com> From: Pankaj Gupta Date: Mon, 12 Jul 2021 12:17:52 +0200 Message-ID: Subject: Re: [PATCH v1] madvise.2: Document MADV_POPULATE_READ and MADV_POPULATE_WRITE To: David Hildenbrand Cc: linux-man@vger.kernel.org, Alejandro Colomar , Michael Kerrisk , Andrew Morton , Michal Hocko , Oscar Salvador , Jann Horn , Mike Rapoport , Linux API , Linux MM Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: CB64410036B2 X-Stat-Signature: mqu38g86inh5a6g3ux6n7ign1st3smf3 Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=gmail.com header.s=20161025 header.b=mNyl0Rh5; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf07.hostedemail.com: domain of pankajguptalinux@gmail.com designates 209.85.166.176 as permitted sender) smtp.mailfrom=pankajguptalinux@gmail.com X-HE-Tag: 1626085083-648997 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: > >> +.BR MADV_POPULATE_WRITE " (since Linux 5.14) > >> +Populate (prefault) page tables writable for the whole range without actually > >> +writing. Depending on the underlying mapping, preallocate memory or read the > > > > Is this read or write? > > just reading and trying to understand :) > > It's reading. Assume you have a file with existing content mapped into a > process. Once you touch a page (read/write/execute) that maps to blocks > with existing content, you'll have to load these blocks from disk first. Got it. Thanks for explaining! Best regards, Pankaj