From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758501AbcIZIqV (ORCPT ); Mon, 26 Sep 2016 04:46:21 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:34320 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753309AbcIZIqT (ORCPT ); Mon, 26 Sep 2016 04:46:19 -0400 Date: Mon, 26 Sep 2016 10:46:16 +0200 From: Michal Hocko To: Oleg Nesterov Cc: Robert Ho , pbonzini@redhat.com, akpm@linux-foundation.org, dan.j.williams@intel.com, dave.hansen@intel.com, guangrong.xiao@linux.intel.com, gleb@kernel.org, mtosatti@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, stefanha@redhat.com, yuhuang@redhat.com, linux-mm@kvack.org, ross.zwisler@linux.intel.com Subject: Re: [PATCH v3 1/2] mm, proc: Fix region lost in /proc/self/smaps Message-ID: <20160926084616.GA28550@dhcp22.suse.cz> References: <1474636354-25573-1-git-send-email-robert.hu@intel.com> <20160923135635.GB28734@redhat.com> <20160923145301.GU4478@dhcp22.suse.cz> <20160923155351.GA1584@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160923155351.GA1584@redhat.com> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 23-09-16 17:53:51, Oleg Nesterov wrote: > On 09/23, Michal Hocko wrote: > > > > On Fri 23-09-16 15:56:36, Oleg Nesterov wrote: > > > > > > I think we can simplify this patch. And imo make it better. How about > > > > it is certainly less subtle because it doesn't report "sub-vmas". > > > > > if (last_addr) { > > > vma = find_vma(mm, last_addr - 1); > > > if (vma && vma->vm_start <= last_addr) > > > vma = m_next_vma(priv, vma); > > > if (vma) > > > return vma; > > > } > > > > we would still miss a VMA if the last one got shrunk/split > > Not sure I understand what you mean... If the last one was split > we probably should not report the new vma. Right, VMA split is less of a problem. I meant to say that if the last_vma->vm_end got lower for whatever reason then we could miss a VMA right after. We actually might want to display such a VMA because it could be a completely new one. We just do not know whether it is a former split with enlarged VMA or a completely new one [ old VMA ] Hole [ VMA ] [ old VMA ][ New VMa ] [ VMA ] > Nevermind, in any case yes, sure, this can't "fix" other corner cases. Agreed, or at least I do not see an easy way for that. -- Michal Hocko SUSE Labs