From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f200.google.com (mail-wr0-f200.google.com [209.85.128.200]) by kanga.kvack.org (Postfix) with ESMTP id 3D3C3831D3 for ; Wed, 8 Mar 2017 04:22:54 -0500 (EST) Received: by mail-wr0-f200.google.com with SMTP id y51so9093103wry.6 for ; Wed, 08 Mar 2017 01:22:54 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id r205si7539968wma.48.2017.03.08.01.22.52 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 08 Mar 2017 01:22:53 -0800 (PST) Date: Wed, 8 Mar 2017 10:22:51 +0100 From: Michal Hocko Subject: Re: [PATCH] mm, vmalloc: use __GFP_HIGHMEM implicitly Message-ID: <20170308092251.GC11028@dhcp22.suse.cz> References: <20170307141020.29107-1-mhocko@kernel.org> <20170307150845.075cceea71647bfeba3c5e22@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170307150845.075cceea71647bfeba3c5e22@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Al Viro , Vlastimil Babka , David Rientjes , Cristopher Lameter , linux-mm@kvack.org, LKML On Tue 07-03-17 15:08:45, Andrew Morton wrote: > On Tue, 7 Mar 2017 15:10:20 +0100 Michal Hocko wrote: > > > __vmalloc* allows users to provide gfp flags for the underlying > > allocation. This API is quite popular > > $ git grep "=[[:space:]]__vmalloc\|return[[:space:]]*__vmalloc" | wc -l > > 77 > > > > the only problem is that many people are not aware that they really want > > to give __GFP_HIGHMEM along with other flags because there is really no > > reason to consume precious lowmemory on CONFIG_HIGHMEM systems for pages > > which are mapped to the kernel vmalloc space. About half of users don't > > use this flag, though. This signals that we make the API unnecessarily > > too complex. > > > > This patch simply uses __GFP_HIGHMEM implicitly when allocating pages to > > be mapped to the vmalloc space. Current users which add __GFP_HIGHMEM > > are simplified and drop the flag. > > hm. What happens if a caller wants only lowmem pages? Drivers do > weird stuff... Yes they do and we have vmalloc_32 API which works as intended because GFP_VMALLOC32 contains GFP_DMA32 and that will override __GFP_HIGHMEM. -- 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