From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f199.google.com (mail-wr0-f199.google.com [209.85.128.199]) by kanga.kvack.org (Postfix) with ESMTP id C6E1D6B0005 for ; Wed, 18 Apr 2018 03:54:39 -0400 (EDT) Received: by mail-wr0-f199.google.com with SMTP id 47-v6so872217wru.19 for ; Wed, 18 Apr 2018 00:54:39 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id r53si916491edd.42.2018.04.18.00.54.38 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 18 Apr 2018 00:54:38 -0700 (PDT) Date: Wed, 18 Apr 2018 09:54:37 +0200 From: Michal Hocko Subject: Re: [PATCH] mm:memcg: add __GFP_NOWARN in __memcg_schedule_kmem_cache_create Message-ID: <20180418075437.GP17484@dhcp22.suse.cz> References: <20180418022912.248417-1-minchan@kernel.org> <20180418072002.GN17484@dhcp22.suse.cz> <20180418074117.GA210164@rodete-desktop-imager.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180418074117.GA210164@rodete-desktop-imager.corp.google.com> Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: Andrew Morton , LKML , linux-mm , Johannes Weiner , Vladimir Davydov On Wed 18-04-18 16:41:17, Minchan Kim wrote: > On Wed, Apr 18, 2018 at 09:20:02AM +0200, Michal Hocko wrote: > > On Wed 18-04-18 11:29:12, Minchan Kim wrote: [...] > > > Let's not make user scared. > > > > This is not a proper explanation. So what exactly happens when this > > allocation fails? I would suggest something like the following > > " > > __memcg_schedule_kmem_cache_create tries to create a shadow slab cache > > and the worker allocation failure is not really critical because we will > > retry on the next kmem charge. We might miss some charges but that > > shouldn't be critical. The excessive allocation failure report is not > > very much helpful. Replace it with a rate limited single line output so > > that we know that there is a lot of these failures and that we need to > > do something about it in future. > > " > > > > With the last part to be implemented of course. > > If you want to see warning and catch on it in future, I don't see any reason > to change it. Because I didn't see any excessive warning output that it could > make system slow unless we did ratelimiting. Yeah, but a single line would be as much informative and less scary to users. > It was a just report from non-MM guys who have a concern that somethings > might go wrong on the system. I just wanted them relax since it's not > critical. I do agree with __GFP_NOWARN but I think a single line warning is due and helpful for further debugging. -- Michal Hocko SUSE Labs