From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f70.google.com (mail-pl0-f70.google.com [209.85.160.70]) by kanga.kvack.org (Postfix) with ESMTP id BDA346B0003 for ; Thu, 15 Feb 2018 10:57:40 -0500 (EST) Received: by mail-pl0-f70.google.com with SMTP id b34so58373plc.2 for ; Thu, 15 Feb 2018 07:57:40 -0800 (PST) Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com. [66.63.167.143]) by mx.google.com with ESMTPS id w3si2675458pgb.754.2018.02.15.07.57.39 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 15 Feb 2018 07:57:39 -0800 (PST) Message-ID: <1518710257.5399.4.camel@HansenPartnership.com> Subject: Re: [Lsf-pc] [LSF/MM ATTEND] memory allocation scope From: James Bottomley Date: Thu, 15 Feb 2018 07:57:37 -0800 In-Reply-To: <20180215144807.GH7275@dhcp22.suse.cz> References: <8b9d4170-bc71-3338-6b46-22130f828adb@suse.de> <20180215144807.GH7275@dhcp22.suse.cz> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko , Goldwyn Rodrigues Cc: Linux FS-devel Mailing List , linux-mm@kvack.org, lsf-pc@lists.linux-foundation.org On Thu, 2018-02-15 at 15:48 +0100, Michal Hocko wrote: > On Wed 14-02-18 16:51:53, Goldwyn Rodrigues wrote: > > > > > > Discussion with the memory folks towards scope based allocation > > I am working on converting some of the GFP_NOFS memory allocation > > calls to new scope API [1]. While other allocation types (noio, > > nofs, noreclaim) are covered. Are there plans for identifying scope > > of GFP_ATOMIC allocations? This should cover most (if not all) of > > the allocation scope. > > There was no explicit request for that but I can see how some users > might want it. I would have to double check but maybe this would > allow vmalloc(GFP_ATOMIC). There were some users but most of them > could have been changed in some way so the motivation is not very > large. We have to be careful about that: most GFP_ATOMIC allocations are in drivers and may be for DMA'able memory. A We can't currently use vmalloc memory for DMA to kernel via block because bio_map_kern() uses virt_to_page() which assumes offset mapping. A The latter is fixable, obviously, but is it worth fixing? A Very few GFP_ATOMIC allocations in drivers will be for large chunks. James -- 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