From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751543AbeAWMpt (ORCPT ); Tue, 23 Jan 2018 07:45:49 -0500 Received: from mx2.suse.de ([195.135.220.15]:37729 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751215AbeAWMps (ORCPT ); Tue, 23 Jan 2018 07:45:48 -0500 Date: Tue, 23 Jan 2018 13:45:45 +0100 From: Michal Hocko To: Anshuman Khandual Cc: Michael Ellerman , akpm@linux-foundation.org, mm-commits@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-next@vger.kernel.org, sfr@canb.auug.org.au, broonie@kernel.org Subject: Re: ppc elf_map breakage with MAP_FIXED_NOREPLACE Message-ID: <20180123124545.GL1526@dhcp22.suse.cz> References: <20180107090229.GB24862@dhcp22.suse.cz> <87mv1phptq.fsf@concordia.ellerman.id.au> <7a44f42e-39d0-1c4b-19e0-7df1b0842c18@linux.vnet.ibm.com> <87tvvw80f2.fsf@concordia.ellerman.id.au> <96458c0a-e273-3fb9-a33b-f6f2d536f90b@linux.vnet.ibm.com> <20180109161355.GL1732@dhcp22.suse.cz> <20180117080731.GA2900@dhcp22.suse.cz> <082aa008-c56a-681d-0949-107245603a97@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <082aa008-c56a-681d-0949-107245603a97@linux.vnet.ibm.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 23-01-18 16:55:18, Anshuman Khandual wrote: > On 01/17/2018 01:37 PM, Michal Hocko wrote: > > On Thu 11-01-18 15:38:37, Anshuman Khandual wrote: > >> On 01/09/2018 09:43 PM, Michal Hocko wrote: > > [...] > >>> Did you manage to catch _who_ is requesting that anonymous mapping? Do > >>> you need a help with the debugging patch? > >> > >> Not yet, will get back on this. > > > > ping? > > Hey Michal, > > Missed this thread, my apologies. This problem is happening only with > certain binaries like 'sed', 'tmux', 'hostname', 'pkg-config' etc. As > you had mentioned before the map request collision is happening on > [10030000, 10040000] and [10030000, 10040000] ranges only which is > just a single PAGE_SIZE. You asked previously that who might have > requested the anon mapping which is already present in there ? Would > not that be the same process itself ? I am bit confused. We are early in the ELF loading. If we are mapping over an existing mapping then we are effectivelly corrupting it. In other words exactly what this patch tries to prevent. I fail to see what would be a relevant anon mapping this early and why it would be colliding with elf segements. > Would it be > helpful to trap all the mmap() requests from any of the binaries > and see where we might have created that anon mapping ? Yeah, that is exactly what I was suggesting. Sorry for not being clear about that. -- Michal Hocko SUSE Labs