From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f198.google.com (mail-wr0-f198.google.com [209.85.128.198]) by kanga.kvack.org (Postfix) with ESMTP id 2F28F6B0003 for ; Fri, 16 Mar 2018 07:44:47 -0400 (EDT) Received: by mail-wr0-f198.google.com with SMTP id q15so5342056wra.22 for ; Fri, 16 Mar 2018 04:44:47 -0700 (PDT) Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com. [148.163.158.5]) by mx.google.com with ESMTPS id f16si747994edf.124.2018.03.16.04.44.45 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 16 Mar 2018 04:44:45 -0700 (PDT) Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w2GBhrTn142477 for ; Fri, 16 Mar 2018 07:44:44 -0400 Received: from e06smtp13.uk.ibm.com (e06smtp13.uk.ibm.com [195.75.94.109]) by mx0b-001b2d01.pphosted.com with ESMTP id 2grc2ju0n9-1 (version=TLSv1.2 cipher=AES256-SHA256 bits=256 verify=NOT) for ; Fri, 16 Mar 2018 07:44:43 -0400 Received: from localhost by e06smtp13.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 16 Mar 2018 11:44:41 -0000 Subject: Re: [PATCH 5/8] trace_uprobe: Support SDT markers having reference count (semaphore) References: <20180313125603.19819-1-ravi.bangoria@linux.vnet.ibm.com> <20180313125603.19819-6-ravi.bangoria@linux.vnet.ibm.com> <20180315142120.GA19218@redhat.com> <20180315143044.GA19643@redhat.com> <3b303a2d-35dd-9178-fc03-de9f2d588797@linux.vnet.ibm.com> <20180316113917.GA21303@redhat.com> From: Ravi Bangoria Date: Fri, 16 Mar 2018 17:16:49 +0530 MIME-Version: 1.0 In-Reply-To: <20180316113917.GA21303@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Message-Id: <663244e6-2de0-48bb-08d1-fbc66b3c736b@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Oleg Nesterov Cc: mhiramat@kernel.org, peterz@infradead.org, srikar@linux.vnet.ibm.com, acme@kernel.org, ananth@linux.vnet.ibm.com, akpm@linux-foundation.org, alexander.shishkin@linux.intel.com, alexis.berlemont@gmail.com, corbet@lwn.net, dan.j.williams@intel.com, gregkh@linuxfoundation.org, huawei.libin@huawei.com, hughd@google.com, jack@suse.cz, jglisse@redhat.com, jolsa@redhat.com, kan.liang@intel.com, kirill.shutemov@linux.intel.com, kjlx@templeofstupid.com, kstewart@linuxfoundation.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.com, milian.wolff@kdab.com, mingo@redhat.com, namhyung@kernel.org, naveen.n.rao@linux.vnet.ibm.com, pc@us.ibm.com, pombredanne@nexb.com, rostedt@goodmis.org, tglx@linutronix.de, tmricht@linux.vnet.ibm.com, willy@infradead.org, yao.jin@linux.intel.com, fengguang.wu@intel.com, Ravi Bangoria On 03/16/2018 05:09 PM, Oleg Nesterov wrote: > On 03/16, Ravi Bangoria wrote: >> On 03/15/2018 08:00 PM, Oleg Nesterov wrote: >>> Note to mention that sdt_find_vma() can return NULL but the callers do >>> vma_offset_to_vaddr(vma) without any check. >> If the "mm" we are passing to sdt_find_vma() is returned by >> uprobe_build_map_info(ref_ctr_offset), sdt_find_vma() must >> _not_ return NULL. > Not at all. > > Once build_map_info() returns any mapping can go away. Otherwise, why do > you think the caller has to take ->mmap_sem and use find_vma()? If you > were right, build_map_info() could just return the list of vma's instead > of list of mm's. Oh.. okay.. I was under wrong impression then. Will add a check there. Thanks for the review :) Ravi