From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751323AbdAPTlL (ORCPT ); Mon, 16 Jan 2017 14:41:11 -0500 Received: from mx2.suse.de ([195.135.220.15]:41910 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751214AbdAPTlI (ORCPT ); Mon, 16 Jan 2017 14:41:08 -0500 Date: Mon, 16 Jan 2017 20:40:53 +0100 From: Michal Hocko To: John Hubbard Cc: Andrew Morton , Vlastimil Babka , David Rientjes , Mel Gorman , Johannes Weiner , Al Viro , linux-mm@kvack.org, LKML , Anatoly Stepanov , Paolo Bonzini , Mike Snitzer , "Michael S. Tsirkin" , "Theodore Ts'o" Subject: Re: [PATCH 1/6] mm: introduce kv[mz]alloc helpers Message-ID: <20170116194052.GA9382@dhcp22.suse.cz> References: <20170112153717.28943-1-mhocko@kernel.org> <20170112153717.28943-2-mhocko@kernel.org> <20170116084717.GA13641@dhcp22.suse.cz> <0ca8a212-c651-7915-af25-23925e1c1cc3@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0ca8a212-c651-7915-af25-23925e1c1cc3@nvidia.com> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 16-01-17 11:09:37, John Hubbard wrote: > > > On 01/16/2017 12:47 AM, Michal Hocko wrote: > > On Sun 15-01-17 20:34:13, John Hubbard wrote: [...] > > > Is that "Reclaim modifiers" line still true, or is it a leftover from an > > > earlier approach? I am having trouble reconciling it with rest of the > > > patchset, because: > > > > > > a) the flags argument below is effectively passed on to either kmalloc_node > > > (possibly adding, but not removing flags), or to __vmalloc_node_flags. > > > > The above only says thos are _unsupported_ - in other words the behavior > > is not defined. Even if flags are passed down to kmalloc resp. vmalloc > > it doesn't mean they are used that way. Remember that vmalloc uses > > some hardcoded GFP_KERNEL allocations. So while I could be really > > strict about this and mask away these flags I doubt this is worth the > > additional code. > > I do wonder about passing those flags through to kmalloc. Maybe it is worth > stripping out __GFP_NORETRY and __GFP_NOFAIL, after all. It provides some > insulation from any future changes to the implementation of kmalloc, and it > also makes the documentation more believable. I am not really convinced that we should take an extra steps for these flags. There are no existing users for those flags and new users should follow the documentation. -- Michal Hocko SUSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f72.google.com (mail-wm0-f72.google.com [74.125.82.72]) by kanga.kvack.org (Postfix) with ESMTP id 190A96B0038 for ; Mon, 16 Jan 2017 14:41:03 -0500 (EST) Received: by mail-wm0-f72.google.com with SMTP id r126so29556327wmr.2 for ; Mon, 16 Jan 2017 11:41:03 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id f124si13527877wmd.64.2017.01.16.11.41.01 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 16 Jan 2017 11:41:01 -0800 (PST) Date: Mon, 16 Jan 2017 20:40:53 +0100 From: Michal Hocko Subject: Re: [PATCH 1/6] mm: introduce kv[mz]alloc helpers Message-ID: <20170116194052.GA9382@dhcp22.suse.cz> References: <20170112153717.28943-1-mhocko@kernel.org> <20170112153717.28943-2-mhocko@kernel.org> <20170116084717.GA13641@dhcp22.suse.cz> <0ca8a212-c651-7915-af25-23925e1c1cc3@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0ca8a212-c651-7915-af25-23925e1c1cc3@nvidia.com> Sender: owner-linux-mm@kvack.org List-ID: To: John Hubbard Cc: Andrew Morton , Vlastimil Babka , David Rientjes , Mel Gorman , Johannes Weiner , Al Viro , linux-mm@kvack.org, LKML , Anatoly Stepanov , Paolo Bonzini , Mike Snitzer , "Michael S. Tsirkin" , Theodore Ts'o On Mon 16-01-17 11:09:37, John Hubbard wrote: > > > On 01/16/2017 12:47 AM, Michal Hocko wrote: > > On Sun 15-01-17 20:34:13, John Hubbard wrote: [...] > > > Is that "Reclaim modifiers" line still true, or is it a leftover from an > > > earlier approach? I am having trouble reconciling it with rest of the > > > patchset, because: > > > > > > a) the flags argument below is effectively passed on to either kmalloc_node > > > (possibly adding, but not removing flags), or to __vmalloc_node_flags. > > > > The above only says thos are _unsupported_ - in other words the behavior > > is not defined. Even if flags are passed down to kmalloc resp. vmalloc > > it doesn't mean they are used that way. Remember that vmalloc uses > > some hardcoded GFP_KERNEL allocations. So while I could be really > > strict about this and mask away these flags I doubt this is worth the > > additional code. > > I do wonder about passing those flags through to kmalloc. Maybe it is worth > stripping out __GFP_NORETRY and __GFP_NOFAIL, after all. It provides some > insulation from any future changes to the implementation of kmalloc, and it > also makes the documentation more believable. I am not really convinced that we should take an extra steps for these flags. There are no existing users for those flags and new users should follow the documentation. -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org