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=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham 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 CC6E0C28CF6 for ; Thu, 26 Jul 2018 14:20:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 93B6E20685 for ; Thu, 26 Jul 2018 14:20:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 93B6E20685 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730413AbeGZPhq (ORCPT ); Thu, 26 Jul 2018 11:37:46 -0400 Received: from mx2.suse.de ([195.135.220.15]:60368 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729894AbeGZPhq (ORCPT ); Thu, 26 Jul 2018 11:37:46 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id EE507AFC6; Thu, 26 Jul 2018 14:20:39 +0000 (UTC) Date: Thu, 26 Jul 2018 16:20:39 +0200 From: Michal Hocko To: Matthew Wilcox Cc: Mike Rapoport , Jonathan Corbet , Andrew Morton , linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 7/7] docs/core-api: mm-api: add section about GFP flags Message-ID: <20180726142039.GA23627@dhcp22.suse.cz> References: <1532607722-17079-1-git-send-email-rppt@linux.vnet.ibm.com> <1532607722-17079-8-git-send-email-rppt@linux.vnet.ibm.com> <20180726130106.GC3504@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180726130106.GC3504@bombadil.infradead.org> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 26-07-18 06:01:06, Matthew Wilcox wrote: > On Thu, Jul 26, 2018 at 03:22:02PM +0300, Mike Rapoport wrote: > > +Memory Allocation Controls > > +========================== > > Perhaps call this section "Memory Allocation Flags" instead? > > > +Linux provides a variety of APIs for memory allocation from direct > > +calls to page allocator through slab caches and vmalloc to allocators > > +of compressed memory. Although these allocators have different > > +semantics and are used in different circumstances, they all share the > > +GFP (get free page) flags that control behavior of each allocation > > +request. > > While this isn't /wrong/, I think it might not be the most useful way > of explaining what the GFP flags are to someone who's just come across > them in some remote part of the kernel. How about this paragraph instead? > > Functions which need to allocate memory often use GFP flags to express > how that memory should be allocated. The GFP acronym stands for "get > free pages", the underlying memory allocation function. OK. > Not every GFP > flag is allowed to every function which may allocate memory. Most > users will want to use a plain ``GFP_KERNEL`` or ``GFP_ATOMIC``. Or rather than mentioning the two just use "Useful GFP flag combinations" comment segment from gfp.h -- Michal Hocko SUSE Labs