Return-Path: Received: from mx2.suse.de ([195.135.220.15]:48670 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754957AbdEKH7O (ORCPT ); Thu, 11 May 2017 03:59:14 -0400 Date: Thu, 11 May 2017 09:59:11 +0200 From: Michal Hocko To: Nikolay Borisov Cc: Trond Myklebust , "torvalds@linux-foundation.org" , "linux-kernel@vger.kernel.org" , "linux-nfs@vger.kernel.org" Subject: Re: [GIT PULL] Please pull NFS client fixes for 4.12 Message-ID: <20170511075910.GD26782@dhcp22.suse.cz> References: <1494434821.4764.1.camel@primarydata.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-nfs-owner@vger.kernel.org List-ID: On Thu 11-05-17 10:53:27, Nikolay Borisov wrote: > > > On 10.05.2017 19:47, Trond Myklebust wrote: [...] > > - Cleanup and removal of some memory failure paths now that > > GFP_NOFS is guaranteed to never fail. > > What guarantees that? Since if this is the case then this can result in > a lot of opportunities for cleanup across the whole kernel tree. After > discussing with mhocko (cc'ed) it seems that in practice everything > below COSTLY_ORDER which are not GFP_NORETRY will never fail. But this > semantic is not the same as GFP_NOFAIL. E.g. nothing guarantees that > this will stay like that in the future? In practice it is hard to change the semantic of small allocations never fail _practically_. But this is absolutely not guaranteed! They can fail e.g. when the allocation context is the oom victim. Removing error paths for allocation failures is just wrong. -- Michal Hocko SUSE Labs