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 151496B0260 for ; Thu, 26 Jan 2017 09:13:54 -0500 (EST) Received: by mail-wm0-f72.google.com with SMTP id r144so45231098wme.0 for ; Thu, 26 Jan 2017 06:13:54 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id x5si3188406wmg.133.2017.01.26.06.13.52 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 26 Jan 2017 06:13:52 -0800 (PST) Date: Thu, 26 Jan 2017 15:13:49 +0100 From: Michal Hocko Subject: Re: [PATCH 0/6 v3] kvmalloc Message-ID: <20170126141349.GN6590@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> <20170126115833.GI6590@dhcp22.suse.cz> <5889F52E.7030602@iogearbox.net> <20170126134004.GM6590@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170126134004.GM6590@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: 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 On Thu 26-01-17 14:40:04, Michal Hocko wrote: > On Thu 26-01-17 14:10:06, Daniel Borkmann wrote: > > On 01/26/2017 12:58 PM, Michal Hocko wrote: > > > 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 > > > > Hmm. 'On my own' means, we could potentially BUG somewhere down the > > vmalloc implementation, etc, presumably? So it might in-fact be > > harmful to pass that, right? > > No it would mean that it might eventually hit the behavior which you are > trying to avoid - in other words it may invoke OOM killer even though > __GFP_NORETRY means giving up before any system wide disruptive actions > a re taken. I will separate both bpf and netfilter hunks into its own patch with the clarification. Does the following look better? ---