From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756820AbdLPLwc (ORCPT ); Sat, 16 Dec 2017 06:52:32 -0500 Received: from mx2.suse.de ([195.135.220.15]:45191 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752809AbdLPLw3 (ORCPT ); Sat, 16 Dec 2017 06:52:29 -0500 Date: Sat, 16 Dec 2017 12:52:27 +0100 From: Michal Hocko To: Andrew Morton Cc: JianKang Chen , mgorman@techsingularity.net, hannes@cmpxchg.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, xieyisheng1@huawei.com, guohanjun@huawei.com, wangkefeng.wang@huawei.com Subject: Re: [PATCH resend] mm/page_alloc: fix comment is __get_free_pages Message-ID: <20171216115227.GI16951@dhcp22.suse.cz> References: <20171129160446.jluzpv3n6mjc3fwv@dhcp22.suse.cz> <20171129134159.c9100ea6dacad870d69929b7@linux-foundation.org> <20171130065335.zno7peunnl2zpozq@dhcp22.suse.cz> <20171130131706.0550cd28ce47aaa976f7db2a@linux-foundation.org> <20171201072414.3kc3pbvdbqbxhnfx@dhcp22.suse.cz> <20171201111845.iyoua7hhjodpuvoy@dhcp22.suse.cz> <20171214140608.GQ16951@dhcp22.suse.cz> <20171214123309.bdee142c82809f4c4ff3ce5b@linux-foundation.org> <20171215093618.GV16951@dhcp22.suse.cz> <20171215125735.1d74c7a04c05d91f27ffdbd7@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171215125735.1d74c7a04c05d91f27ffdbd7@linux-foundation.org> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 15-12-17 12:57:35, Andrew Morton wrote: > On Fri, 15 Dec 2017 10:36:18 +0100 Michal Hocko wrote: > > > > > > > > > So do we care and I will resend the patch in that case or I just drop > > > > this from my patch queue? > > > > > > Well.. I still think that silently accepting bad input would be bad > > > practice. If we can just delete the assertion and have such a caller > > > reliably blow up later on then that's good enough. > > > > The point is that if the caller checks for the failed allocation then > > the result is a memory leak. > > That's if page_address(highmem page) returns NULL. I'm not sure what > it returns, really - so many different implementations across so many > different architectures. I am not sure I follow. We only do care for HIGHMEM, right? And that one returns NULL unless the high mem page is not kmaped. > Oh well, it would have been nice to remove that VM_BUG_ON(). Why not > just leave the code as it is now? BUGing on a bogus usage is not popular anymore. Also checking for something nobody actually does is a bit pointless. I will not insist though. -- Michal Hocko SUSE Labs