Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752127AbcDPUbp (ORCPT ); Sat, 16 Apr 2016 16:31:45 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:34943 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751711AbcDPUbo (ORCPT ); Sat, 16 Apr 2016 16:31:44 -0400 Date: Sat, 16 Apr 2016 16:31:36 -0400 From: Michal Hocko To: Mikulas Patocka Cc: linux-mm@kvack.org, Andrew Morton , LKML , Shaohua Li Subject: Re: [PATCH 17/19] dm: get rid of superfluous gfp flags Message-ID: <20160416203135.GC15128@dhcp22.suse.cz> References: <1460372892-8157-1-git-send-email-mhocko@kernel.org> <1460372892-8157-18-git-send-email-mhocko@kernel.org> <20160415130839.GJ32377@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1511 Lines: 46 On Fri 15-04-16 14:41:29, Mikulas Patocka wrote: > > > On Fri, 15 Apr 2016, Michal Hocko wrote: > > > On Fri 15-04-16 08:29:28, Mikulas Patocka wrote: > > > > > > > > > On Mon, 11 Apr 2016, Michal Hocko wrote: > > > > > > > From: Michal Hocko > > > > > > > > copy_params seems to be little bit confused about which allocation flags > > > > to use. It enforces GFP_NOIO even though it uses > > > > memalloc_noio_{save,restore} which enforces GFP_NOIO at the page > > > > > > memalloc_noio_{save,restore} is used because __vmalloc is flawed and > > > doesn't respect GFP_NOIO properly (it doesn't use gfp flags when > > > allocating pagetables). > > > > Yes and there are no plans to change __vmalloc to properly propagate gfp > > flags through the whole call chain and that is why we have > > memalloc_noio thingy. If that ever changes later the GFP_NOIO can be > > added in favor of memalloc_noio API. Both are clearly redundant. > > -- > > Michal Hocko > > SUSE Labs > > You could move memalloc_noio_{save,restore} to __vmalloc. Something like > > if (!(gfp_mask & __GFP_IO)) > noio_flag = memalloc_noio_save(); > ... > if (!(gfp_mask & __GFP_IO)) > memalloc_noio_restore(noio_flag); > > That would be better than repeating this hack in every __vmalloc caller > that need GFP_NOIO. It is not my intention to change __vmalloc behavior. If you strongly oppose the GFP_NOIO change I can drop it from the patch. It is __GFP_REPEAT which I am after. -- Michal Hocko SUSE Labs