From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f70.google.com (mail-it0-f70.google.com [209.85.214.70]) by kanga.kvack.org (Postfix) with ESMTP id 419126B0253 for ; Thu, 29 Sep 2016 09:06:33 -0400 (EDT) Received: by mail-it0-f70.google.com with SMTP id p135so60190135itb.2 for ; Thu, 29 Sep 2016 06:06:33 -0700 (PDT) Received: from mga05.intel.com (mga05.intel.com. [192.55.52.43]) by mx.google.com with ESMTPS id v66si14322754pfj.183.2016.09.29.06.06.13 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 29 Sep 2016 06:06:13 -0700 (PDT) Message-ID: <1475154343.16655.1.camel@vmm.sh.intel.com> Subject: Re: [PATCH v3 1/2] mm, proc: Fix region lost in /proc/self/smaps From: Robert Hu Reply-To: robert.hu@intel.com Date: Thu, 29 Sep 2016 21:05:43 +0800 In-Reply-To: <20160923145301.GU4478@dhcp22.suse.cz> References: <1474636354-25573-1-git-send-email-robert.hu@intel.com> <20160923135635.GB28734@redhat.com> <20160923145301.GU4478@dhcp22.suse.cz> Content-Type: text/plain; charset="ISO-8859-15" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Oleg Nesterov , 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 On Fri, 2016-09-23 at 16:53 +0200, Michal Hocko wrote: > On Fri 23-09-16 15:56:36, Oleg Nesterov wrote: > > On 09/23, Robert Ho wrote: > > > > > > --- a/fs/proc/task_mmu.c > > > +++ b/fs/proc/task_mmu.c > > > @@ -147,7 +147,7 @@ m_next_vma(struct proc_maps_private *priv, struct vm_area_struct *vma) > > > static void m_cache_vma(struct seq_file *m, struct vm_area_struct *vma) > > > { > > > if (m->count < m->size) /* vma is copied successfully */ > > > - m->version = m_next_vma(m->private, vma) ? vma->vm_start : -1UL; > > > + m->version = m_next_vma(m->private, vma) ? vma->vm_end : -1UL; > > > } > > > > OK. > > > > > static void *m_start(struct seq_file *m, loff_t *ppos) > > > @@ -176,14 +176,14 @@ static void *m_start(struct seq_file *m, loff_t *ppos) > > > > > > if (last_addr) { > > > vma = find_vma(mm, last_addr); > > > - if (vma && (vma = m_next_vma(priv, vma))) > > > + if (vma) > > > return vma; > > > } > > > > 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 but at least > it would provide monotonic results. So definitely an improvement but > I guess we really want to document that only full reads provide a > consistent (at some moment in time) output. Indeed an improvement. I prefer Oleg's approach as well. > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org