From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-5.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id E8CCB7D072 for ; Thu, 26 Jul 2018 17:24:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388320AbeGZSmV (ORCPT ); Thu, 26 Jul 2018 14:42:21 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:35908 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387611AbeGZSmV (ORCPT ); Thu, 26 Jul 2018 14:42:21 -0400 Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w6QHNnHs003760 for ; Thu, 26 Jul 2018 13:24:34 -0400 Received: from e06smtp05.uk.ibm.com (e06smtp05.uk.ibm.com [195.75.94.101]) by mx0a-001b2d01.pphosted.com with ESMTP id 2kfgdu6as3-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 26 Jul 2018 13:24:33 -0400 Received: from localhost by e06smtp05.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 26 Jul 2018 18:24:28 +0100 Received: from d06av24.portsmouth.uk.ibm.com (d06av24.portsmouth.uk.ibm.com [9.149.105.60]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w6QHOREW32899082 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 26 Jul 2018 17:24:27 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 56E0242047; Thu, 26 Jul 2018 20:24:41 +0100 (BST) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 698DD42041; Thu, 26 Jul 2018 20:24:40 +0100 (BST) Received: from rapoport-lnx (unknown [9.148.204.214]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Thu, 26 Jul 2018 20:24:40 +0100 (BST) Date: Thu, 26 Jul 2018 20:24:23 +0300 From: Mike Rapoport To: Michal Hocko Cc: Matthew Wilcox , 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 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> <20180726142039.GA23627@dhcp22.suse.cz> <20180726151852.GF8477@rapoport-lnx> <20180726164150.GO28386@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180726164150.GO28386@dhcp22.suse.cz> User-Agent: Mutt/1.5.24 (2015-08-30) X-TM-AS-GCONF: 00 x-cbid: 18072617-0020-0000-0000-000002AC6D0E X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18072617-0021-0000-0000-000020F873DB Message-Id: <20180726172423.GA13478@rapoport-lnx> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-07-26_04:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=2 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1806210000 definitions=main-1807260179 Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Thu, Jul 26, 2018 at 06:41:50PM +0200, Michal Hocko wrote: > On Thu 26-07-18 18:18:53, Mike Rapoport wrote: > > On Thu, Jul 26, 2018 at 04:20:39PM +0200, Michal Hocko wrote: > > > 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 > > > > The comment there includes GFP_DMA, GFP_NOIO etc so I'd prefer Matthew's > > version and maybe even omit GFP_ATOMIC from it. > > > > Some grepping shows that roughly 80% of allocations are GFP_KERNEL, 12% are > > GFP_ATOMIC and ... I didn't count the usage of other flags ;-) > > Well, I will certainly not insist... I don't know who is the expected > audience of this documentation. That section was meant for kernel > developers to know which of the high level flags to use. Well, as this is kernel api documentation I presume the audience is the same. All the descriptions from include/linux/gfp.h are converted by by kernel-doc and would be included here. This was actually the point of this patch :) > -- > Michal Hocko > SUSE Labs > -- Sincerely yours, Mike. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html