From patchwork Thu Jan 26 11:58:33 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michal Hocko X-Patchwork-Id: 720092 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3v8L6l3wLSz9t14 for ; Thu, 26 Jan 2017 22:58:55 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752776AbdAZL6i (ORCPT ); Thu, 26 Jan 2017 06:58:38 -0500 Received: from mx2.suse.de ([195.135.220.15]:47113 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752106AbdAZL6h (ORCPT ); Thu, 26 Jan 2017 06:58:37 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id BBDE5AC53; Thu, 26 Jan 2017 11:58:34 +0000 (UTC) Date: Thu, 26 Jan 2017 12:58:33 +0100 From: Michal Hocko To: Daniel Borkmann Cc: Alexei Starovoitov , Andrew Morton , Vlastimil Babka , Mel Gorman , Johannes Weiner , linux-mm , LKML , "netdev@vger.kernel.org" , marcelo.leitner@gmail.com Subject: Re: [PATCH 0/6 v3] kvmalloc Message-ID: <20170126115833.GI6590@dhcp22.suse.cz> References: <588907AA.1020704@iogearbox.net> <20170126074354.GB8456@dhcp22.suse.cz> <5889C331.7020101@iogearbox.net> <20170126100802.GF6590@dhcp22.suse.cz> <5889DEA3.7040106@iogearbox.net> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <5889DEA3.7040106@iogearbox.net> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu 26-01-17 12:33:55, Daniel Borkmann wrote: > On 01/26/2017 11:08 AM, Michal Hocko wrote: [...] > > If you disagree I can drop the bpf part of course... > > If we could consolidate these spots with kvmalloc() eventually, I'm > all for it. But even if __GFP_NORETRY is not covered down to all > possible paths, it kind of does have an effect already of saying > 'don't try too hard', so would it be harmful to still keep that for > now? If it's not, I'd personally prefer to just leave it as is until > there's some form of support by kvmalloc() and friends. Well, you can use kvmalloc(size, GFP_KERNEL|__GFP_NORETRY). It is not disallowed. It is not _supported_ which means that if it doesn't work as you expect you are on your own. Which is actually the situation right now as well. But I still think that this is just not right thing to do. Even though it might happen to work in some cases it gives a false impression of a solution. So I would rather go with diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 8697f43cf93c..a6dc4d596f14 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -53,6 +53,11 @@ void bpf_register_map_type(struct bpf_map_type_list *tl) void *bpf_map_area_alloc(size_t size) { + /* + * FIXME: we would really like to not trigger the OOM killer and rather + * fail instead. This is not supported right now. Please nag MM people + * if these OOM start bothering people. + */ return kvzalloc(size, GFP_USER); }