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, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 04474C35656 for ; Fri, 21 Feb 2020 12:42:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CF2C924683 for ; Fri, 21 Feb 2020 12:42:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="ImxHL/wm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727781AbgBUMmO (ORCPT ); Fri, 21 Feb 2020 07:42:14 -0500 Received: from mail-lf1-f65.google.com ([209.85.167.65]:40878 "EHLO mail-lf1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727686AbgBUMmO (ORCPT ); Fri, 21 Feb 2020 07:42:14 -0500 Received: by mail-lf1-f65.google.com with SMTP id c23so1385089lfi.7 for ; Fri, 21 Feb 2020 04:42:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=BjoBKXIcxCqkMcDtocPoDMNTlqqBgsrHw4ar9iaPBm8=; b=ImxHL/wm/0DS01CiAm6IEyWwr1YLg4Y3BMgGb3qHBzpXs/WO6b5aGLiMLpDzAoh9Tg MJJUjIIODYjwEhY8Iy+ppZfH3ZtHB+J9OXVBESkHQ0QoFjAQI7F/ylY3IiqDeNW1f/FG /iDbwrOK0MFXFLxT0aRtLkbodQsAn34GEkeKad5RP4G1ajX7uEFgyKVrglDwdbkW1ZSE OzU0NvLF0whVrsNO507XNiZkfQ6wCsuB2gM8lTiu0gYap7T/G2rgum0ZXp/fOGY0Ftyq 08vypgcFeiDD7zXPofpZXUzuRdyRMOmnR0wKF8F70sFde2cGAEoLtBdJcnLS17waDJXM euCA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=BjoBKXIcxCqkMcDtocPoDMNTlqqBgsrHw4ar9iaPBm8=; b=bpBy4r+JtP5pqbh0vLlMsrbYhvinfkYVGsQxywLYTsglvxc7vEBcH8/yqXbzFVQKuP 1CHG7NJ9NOFvV0yqHzhvco9MUlbDtp9UF8xCGWxYn6IZ1OXyzb41dIc/CxdB/Yi4wftL KTHTWdSrlkTQQU4lw5tDidI/jLXuFRnIQnR76YzTxr+WtpbjhJYCiB38xi5mSHtbpV5c Jr6grs/BwIQVGsU6n0dwBAI698LwCydZXp093IxIUI/SdDOEjYXhgcQ0LD5whLdeRqOE ko07uz6g3qlSlbgDvN0aPp2wAmupV7SXjbsvN/WJZ+yhSmyJyIzUmuTtTL5lRXCGMBuk bxjA== X-Gm-Message-State: APjAAAWBFAeaXSFiZ4UtrFj1v3XZwLVjcbXojF0nLfBqmbGIkzhyN0zM mRM5nd2mdF04y/HozER7Gxo9iA== X-Google-Smtp-Source: APXvYqwDJ3VvW3VVUq4oyV9v/CU0PsmTsHm77UKYLtap8C0MsC9PnyOumhZw7OnquLEBmI8nLdUKWA== X-Received: by 2002:ac2:4477:: with SMTP id y23mr5248642lfl.135.1582288931518; Fri, 21 Feb 2020 04:42:11 -0800 (PST) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id r21sm1577795ljn.64.2020.02.21.04.42.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Feb 2020 04:42:10 -0800 (PST) Received: by box.localdomain (Postfix, from userid 1000) id AF956100FC3; Fri, 21 Feb 2020 15:42:40 +0300 (+03) Date: Fri, 21 Feb 2020 15:42:40 +0300 From: "Kirill A. Shutemov" To: Matthew Wilcox Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 13/25] fs: Add zero_user_large Message-ID: <20200221124240.tk4p2cx2p53emx5a@box> References: <20200212041845.25879-1-willy@infradead.org> <20200212041845.25879-14-willy@infradead.org> <20200214135248.zqcqx3erb4pnlvmu@box> <20200214160342.GA7778@bombadil.infradead.org> <20200218141634.zhhjgtv44ux23l3l@box> <20200218161349.GS7778@bombadil.infradead.org> <20200218171052.lwd56nr332qjgs5j@box> <20200218180705.GA24185@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200218180705.GA24185@bombadil.infradead.org> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Feb 18, 2020 at 10:07:05AM -0800, Matthew Wilcox wrote: > On Tue, Feb 18, 2020 at 08:10:52PM +0300, Kirill A. Shutemov wrote: > > Acked-by: Kirill A. Shutemov > > Thanks > > > > +#if defined(CONFIG_HIGHMEM) && defined(CONFIG_TRANSPARENT_HUGEPAGE) > > > +void zero_user_segments(struct page *page, unsigned start1, unsigned end1, > > > + unsigned start2, unsigned end2); > > > +#else /* !HIGHMEM || !TRANSPARENT_HUGEPAGE */ > > > > This is a neat trick. I like it. > > > > Although, it means non-inlined version will never get tested :/ > > I worry about that too, but I don't really want to incur the overhead on > platforms people actually use. I'm also worried about latency: kmap_atomic() disables preemption even if system has no highmem. Some archs have way too large THP to clear them with preemption disabled. I *think* there's no real need in preemption disabling in this situation and we can wrap kmap_atomic()/kunmap_atomic() into CONFIG_HIGHMEM. -- Kirill A. Shutemov